Author: Abi Saeed

Abiya (Abi) Saeed is the Extension Horticulture Specialist at Montana State University, located at the beautiful campus in Bozeman. She has a background in entomology, pollinator conservation, and integrated pest management. She received her Master's degree in entomology at the University of Kentucky and is currently working on her PhD in Plant Sciences at Montana State University where she is doing research on urban pollinator conservation. Prior to Montana State University Extension, she has been a horticulture educator at Michigan State University Extension and Colorado State University Extension. Abi is also a recurring panelist on Montana PBS's weekly live call-in TV show: Montana Ag Live.

Underrated Beneficial Arthropods Part 2: Natural Enemies

Continuing with the theme of Underrated Beneficial Arthropods that I brought up in my December post about Underrated Pollinators– I will be focusing on the next category of what I consider the trio of beneficial arthropods (which includes pollinators, natural enemies, and nutrient cyclers).

Natural Enemies

Natural enemies are comprised of predatory and parasitic arthropods, in which one or more life stages of the arthropod feed on other organisms, such as garden pests, thereby killing them. Many gardeners are familiar with this group which includes some of our most ‘famous’ predatory arthropods such as mantids, lady beetles, lacewings, etc. This category, however, contains a plethora of beneficials that you may not always think about because most of what they do often occurs behind the scenes.

This is also a very broad category so this post will not be a comprehensive collection of all the natural enemies out there (because there are literally countless) but will have a variety of some of the most abundant, important, and unique. Like the last post it will be grouped by order or major category of Arthropod, where I will go into examples of the rockstars within that category. I will also include several resources at the end which I used to compile this information and encourage those of you who want to dig deeper into the world of natural enemies to take a look.

Flies

Flies (order: Diptera) are an incredibly diverse group of insects which provide a wide variety of different ecosystem services. They undergo complete metamorphosis (which basically means that they have 4 growth stages starting as an egg, and a major transition from their larval form of maggots that turn into pupae, and then into the adults that we recognize as flies). As such, flies also inhabit countless different ecosystems (including terrestrial and aquatic) and can be found on every continent including Antarctica. We learned about pollinating flies in the Underrated Pollinators blog post but, like many of the arthropods that we are going to cover, flies span all 3 of the major categories of beneficial arthropods. We will discuss them a bit more in-depth in the nutrient cycler category, but for this post I wanted to highlight some examples of the cool predatory and parasitic flies that we can find in our yards and gardens.

Tachinid flies [Tachinidae] are dark-colored medium-sized flies that are recognized by the dark bristles covering the body of the adults (which look similar to house flies). This family contains over 8000 described species and can be found on nearly every continent. The cool thing about this group is that every single species of Tachinids has a parasitic larval stage and many are continually utilized as natural enemies of many common pest species. As such, these flies have also been intentionally imported into various locations for biocontrol purposes. The targets of tachinids include a variety of different arthropods including caterpillars, sawflies, grubs, adult beetles, and many more! To learn more about this awesome group of parasitic flies, check out this excellent article on Tachinids written by Susan Mahr of University of Wisconsin-Madison.

Adult Tachinid fly. Photo: **David Cappaert, Bugwood.org**

Hover flies [Syrphidae] also known as flower flies or ‘Syrphids’ are another awesome group (you might recognize them from their shout-out as pollinators in their bee-resembling adult stage). Larval syrphids can be terrestrial or aquatic. You may recognize the term “rat-tailed maggots” which refers to the aquatic larval syrphids that have a breathing tube resembling a ‘tail’ at the end of their body. They are used in biocontrol of a variety of soft-bodied arthropods including aphids, mealybugs, thrips, mites, and more. To learn more about hover flies, check out this excellent resource about their use as a biocontrol agent from Cornell University.

Syrphid larva feeding on oleander aphid. Photo: **David Cappaert, Bugwood.org**

True Bugs

True bugs (Hemiptera and Homoptera) contain a variety of easily recognizable garden inhabitants that can be characterized by their piercing/sucking mouthparts. Although there are many plant feeders and common pests in this category (including aphids, cicadas, mealybugs, leafhoppers, scale insects, stink bugs, etc.) there are also some excellent natural enemies that don’t always get the spotlight. Often referred to as ‘Predatory Bugs’, this fierce category of insects includes assassin bugs [Reduviidae], big-eyed bugs [Geocoridae], minute pirate bugs [Anthocoridae], damsel bugs [Nabidae], and predatory stink bugs [Pentatomidae]. They vary in shape and size, but feed in the same way: by piercing their prey with their mouthparts and sucking out the fluids. Many are, therefore, excellent biocontrol agents in our yard and garden landscapes. Some are even commercially available for use in greenhouses and hoop houses/high tunnels to suppress populations of common soft bodied insect and mite pests. To learn more about them, check out this great article on Predatory Bugs from Colorado State University.

Assassin bug feeding on elm leafminer. Photo: **Whitney Cranshaw, Colorado State University, Bugwood.org**

Wasps

Wasps (order: Hymenoptera) often strike fear in many people who are unaware of the sheer diversity and complexity of this group of insects. You learned about the pollinating wasps in my last Blog post, but there are also several groups of predatory and parasitoid wasps that are commonly found in our landscapes. Predatory wasps include many different species including the commonly known social wasp species (such as yellow jackets, hornets, and paper wasps) but also include countless other predatory species. One group of these common predators includes the striking family of thread-waisted wasps [Sphecidae]. This family includes spider-hunting wasps, cricket-hunter wasps, and katydid wasps. Another common family includes the cicada-killers [Crabronidae] which are a large and intimidating-looking wasp species that are actually harmless to humans. Both of these groups of solitary wasps work similarly by paralyzing their prey (often characterized by their common names) and then bringing their live bodies back to their underground nests for their larvae to feed on.

Cicada killer wasp carrying a paralyzed cicada back to her nest. Photo: **Ronald F. Billings, Texas A&M Forest Service , Bugwood.org**

Parasitoid wasps are an incredibly large group of wasps which include many species varying greatly in size and shape. If you’ve seen the movie ‘Alien’ you have an idea of what the life cycle of these wasps is like. The mother lays her eggs in a living host (which spans countless species of insects), and her larvae feed on the host from within, until they emerge as adults. This includes groups such as braconid wasps [Braconidae], ichneumon wasps [Ichneumonidae], and families such as Aphelinidae, Scelionidae, Eulophidae, and Trichogrammatidae. Each species of parasitoid wasp needs another species of host insect in which to complete its life cycle, and entomologists estimate that there may be hundreds of thousands of species of these incredible organisms! Many parasitoid wasp species are important biocontrol agents for some very famous insect pests (including the Emerald Ash Borer, which those of us in North America are very familiar with). You can even purchase some commercially available species of these parasitoids to manage certain pests in your gardens and greenhouses. There are even hyperparasitoids which are parasitoid wasps that specifically use other parasitic wasps as hosts. To learn more about the incredible world of wasps, check out this great article by Marissa Schuh from University of Minnesota.

A tomato hornworm caterpillar parasitized by braconid wasps that have emerged from internally feeding on the caterpillar, and exited their white silken pupae as adults. Photo: **Gerald Holmes, Strawberry Center, Cal Poly San Luis Obispo, Bugwood.org**

Beetles

Beetles (order: Coleoptera) are one of the most diverse groups of insects and include groups that fall into each of the three categories of beneficial arthropods. Although some are pests in their larval and/or adult stages (example: Japanese beetles) and feed on a variety of different plant structures including leaves, stems/trunks, fruit, flowers, seeds, and roots. We are also familiar with some of these predatory beetles (with many shining a spotlight on the easily recognizable and lovable lady beetles). That being said, there are countless other groups of predatory and parasitic beetles that can have a significant beneficial impact on our landscapes.

A violet ground beetle (*Carabus violaceus*) which is a nocturnal hunter of slugs. Photo: **Mary C Legg, Mary C Legg, Bugwood.org**

One example of a large group of these are the predatory ground beetles [Carabidae]. This dark and iridescent family of beetles can vary in size and shape. They have distinct and powerful chewing mouthparts (mandibles) which enable them to be excellent generalist predators and scavengers. The more than 40,000 species (spanning every continent except Antarctica) are common garden-inhabitants and perform invaluable services of biocontrol in agricultural, horticultural, and home garden settings.

In addition to feeding on many insect and mollusc pests, certain host-specific groups of plant-feeding beetles are also used in the biological control of weed species (including many noxious weeds) and reared by insectaries for distribution.

Neuroptera

Neuroptera (derived from the Greek words meaning “nerve” and “wing”) is an entire order consisting only of predatory insects! The most famous of this group are the lacewings [Chrysopidae] (which many gardeners recognize as an awesome predator of many soft-bodied garden pests). This order also includes other incredible species such as antlions or “doodle-bugs” [Myrmeleontidae], dobsonflies [Corydalidae], mantidflies or mantid lacewings [Mantispidae], snakeflies [Raphidiidae], and more.

Lacewing larva feeding on potato psyllid. Photo: **Whitney Cranshaw, Colorado State University, Bugwood.org**

Mites

Mites (subclass: Acari) are another often misunderstood group of arthropods. These are arachnids (characterized by 4 pairs of legs and two body segments). Mites feed on countless living and decaying organisms including plants, animals, fungi, yeasts, algae, mosses, and even bacteria. They range in size, though most are tiny and many are even microscopic soil-dwelling organisms. The sheer diversity of mite species (due to their very broad range of ecological roles) indicates that there may be over a million species that have yet to be described.

Many gardeners recognize some common mite pests (such as the two-spotted spider mite), but there are countless predatory mite species as well. Predatory mites [Phytoseiidae] are slightly larger than spider mites, and excellent predators of spider mites and eriophyid mites which are common plant-gall causing mites. There are several species used in biocontrol of soft-bodied insect and mite pests as well as commercially available ones that you can purchase.

Spiders

I am sure that no one reading this post would be surprised to find these amazing arachnids on this list. Although some species are dangerous to humans, most species of spiders will leave you alone, and are incredible predators of lots of indoor and outdoor insect pests. Many humans dislike these 8-legged organisms, though most are still understanding of the important role that they play. Spiders can be strikingly beautiful, colorful, and variable in size and shape. Although some build webs to capture prey, others are active hunters or trappers that capture other organisms on which to feed. Some are even kept as pests (I had 4 tarantulas of my own at one point, and I thoroughly enjoyed observing them daily, and handling the more mild-mannered ones). There is so much that can be said about the incredible role of spiders in our homes, gardens, and natural ecosystems that it would be difficult to condense into a short summary (and may therefore be a separate Blog post in the future since this one is getting pretty lengthy).

Jumping spider. Photo: **Joseph Berger, Bugwood.org**

Centipedes

Centipedes span 4 different orders including soil centipedes [Geophiulomorpha], garden/rock centipedes [Lithobiomorpha], giant centipedes [Scolopendromorpha], and house centipedes [Scutigeromorpha] all of which are carnivorous. This group of arthropods is characterized by many body segments, venomous fangs, and 1 pair of legs per segment. Although many people are creeped out by these ferocious many-legged beasts, they stay out of the way and eat many common pests in home and garden landscapes.

Stone centipede. Photo: **Joseph Berger, Bugwood.org**

I hope that you enjoyed reading about some of your gardening companions, and if nothing else: I hope that it broadened your perspective of all the different critters that share your landscape with you. Stay tuned for my next post in June, which will cover the third and final category of beneficial arthropods: the nutrient cyclers.

Resources

Natural Enemies of Pests. (Colorado State University).
https://agsci.colostate.edu/agbio/ipm/natural-enemies-of-pests/

Tachinid Flies. (University of Wisconsin-Madison).
https://hort.extension.wisc.edu/articles/tachinid-flies/

Syrphid Flies. (University of Minnesota Extension).
https://extension.umn.edu/beneficial-insects/syrphid-flies

Hover Flies. (Cornell University).
https://cals.cornell.edu/new-york-state-integrated-pest-management/outreach-education/fact-sheets/hover-fly-biocontrol-fact-sheet

Wasps are a gardener’s friend. (University of Minnesota Extension). https://extension.umn.edu/yard-and-garden-news/wasps-are-gardeners-friend

Cicada Killer Wasps. (University of Kentucky).
https://entomology.ca.uky.edu/ef004

Parasitoid Wasps. (University of Minnesota).
https://extension.umn.edu/beneficial-insects/parasitoid-wasps

Hyperparasitoid Wasps. (North Carolina State University).
https://entomology.ces.ncsu.edu/biological-control-information-center/beneficial-parasitoids/hyperparasitoids/

Predatory Ground Beetles. (Colorado State University).
https://agsci.colostate.edu/agbio/ipm-pests/ground-beetles/

Biological Control of Weeds. (Washington State University).
http://invasives.wsu.edu/biological/index.htm

Underrated Beneficial Arthropods Part 1: Pollinators

The world of beneficial arthropods (insects and their relatives) far exceeds some of the common critters that we often associate with this category. Many of them perform vital functions in our own yards, gardens, and ecosystems all over the world. A very small sliver of all arthropods are considered pests of any kind though there are certainly some pretty devastating pests in this category. Most of these other organisms are either providing benefits or maintaining important ecosystem functions. They are often overlooked, as some of the more charismatic ones (like butterflies, bees, mantids, and lady beetles) take most of the spotlight. These other not-so-glamorous beneficial arthropods are just as important as the more famous ones, and often perform many tasks that go unseen and underappreciated.

I wanted to talk about each group of common beneficial arthropods (Pollinators, Natural Enemies, and Nutrient Cyclers), but as I was writing, I admittedly got a bit carried away. So in order to prevent this blog post from being extremely long, I decided to split this into 3 parts. Stay tuned for the next installments in my spring and summer GP blog posts. In the meantime let’s dig into some under-appreciated pollinators.

Underrated Pollinators

Goldenrod Soldier Beetle ( *Chauliognathus pensylvanicus*) feeding on pollen. Photo: Abiya Saeed

Ah yes, pollinators! Many people consider this their favorite category of beneficials (because very few things are as striking or charismatic as a bee or butterfly sipping nectar from a flower). This is also one of the first groups that come to mind when people think about beneficials in general. The classic image of a monarch butterfly or a honey bee on a flower is often associated as the representative image of this group. That being said, honey bees are just one example of the over 20,000 bee species that are found worldwide. But this group far exceeds butterflies and bees- and some of the less charismatic critters often get an unfair reputation, or just a lack of awareness about what they do. For a variety of reasons, including their anatomy, efficiency, abundance, and direct economic impact, bees are considered the most important pollinators. But many other animals are also great pollinators, some of which are the sole pollinators of certain plant species. In fact most arthropods that visit flowers have the potential to move pollen around, making them possible pollinators. But since I don’t have time to write a whole book’s worth of information into this blog post, I will focus on a few of the larger groups of these less famous pollinators. If you are interested in doing a deeper dive into the world of beneficial arthropods, I will include some resources at the end.

Flies

Flies (order: Diptera) are a huge group of insects, with over 110,000 described species in 150 different families. This group spans a wide variety of very well-known groups like house flies [Muscoidea] and mosquitoes [Culicidae], to not so well-known groups like stalk-eyed flies [Diopsidae] and long-legged flies [Dolichopodidae]. They encompass nearly all biomes and have a broad range of functional groups including predators, parasites, decomposers, and pollinators. In fact, some studies consider flies to be the second most important flower visitors after bees.

Green Bottle Fly (*Lucilia* sp.) on a Prickly Pear (*Opuntia* sp.) Photo: Abiya Saeed

According to a literature review by Cook et al. (2020): flies from 86 different families have been reported to visit over 1100 plant species. These flower-visiting fly species also include some that have important potential for crop pollination and have been recorded to visit many horticultural crops. This includes commonly known pollinating flies, e.g., bee flies [Bombyliidae], hoverflies [Syrphidae], and flower flies [Anthomyiidae]. But some flies we don’t usually associate with this role such as blow flies [Calliphoridae], flesh flies [Sarcophagidae], and horse flies [Tabanidae], and some that many may never have heard of such as nose flies [Rhiniidae] and march flies [Bibionidae], are included. Some species are even considered to have potential as managed pollinators, a role that we most commonly associate with honey bees and some other bee species.

Fun fact: only female mosquitoes need a blood meal in order to reproduce, whereas male mosquitoes feed on nectar, making mosquitoes pollinators! In fact, mosquitoes have been studied as pollinators of orchids, like the Blunt-leaf Orchid, Platanthera obtusata, among other plants.

Moths

We all know butterflies and moths (order: Lepidoptera) are well-documented flower visitors and important pollinators. Despite this, butterflies often get most of the limelight and attention from the general public while many moths often end up being overlooked. Even though moths make up nearly 90% of the over 160,000 described Lepidoptera species, there is a disproportionate amount of research that has historically been conducted on them when compared with butterflies. It has also been demonstrated that moths are the most important nocturnal pollinators, which is fairly intuitive when you think about their nocturnal foraging biology. A study conducted in Sussex by Anderson et al. (2023) demonstrated that moths had higher pollen deposition rates on bramble species indicating that they are more efficient pollinators of brambles than their diurnal counterparts. This has implications for the importance of moths in other plant groups as well, as new research continues to be conducted.

Clearwing Moth (*Hemaris* sp.) Photo: **Steven Katovich, Bugwood.org**

Fun fact: My favorite story to tell about plant-pollinator interactions is of Darwin’s Star Orchid (Angraecum sesquipedale). Charles Darwin was sent a sample of this striking orchid from Madagascar in 1862. Upon examination he found that the nectar tubes were 30 cm (~12 inches) deep! Based on this, Darwin hypothesized that it would take something that has a really long tongue to be able to access that nectar but nobody believed there could be such an insect and he was ridiculed by other scientists. In 1867 Alfred Russel Wallace examined the orchid and predicted there must be a moth in Madagascar that can reach this nectar in order to pollinate the plant. But no moth had ever been discovered which had a proboscis (a coiled and elongated mouthpart of butterflies and moths that is used to suck up nectar) that long. It wasn’t until decades later in 1903 a moth meeting these specifications was discovered. Aptly named in honor of the scientist who predicted its existence, Wallace’s sphinx moth (Xanthopan praedicta) also known as the ‘predicted moth’ has the longest proboscis (sometimes referred to as a tongue, though it is not quite a tongue) of any insect. This just demonstrates just how amazing plant and insect interactions and coevolutionary relationships truly are!

The Star Orchid alongside the ‘Predicted Moth’! Photographed by Robert Clark for Evolution

Wasps

Wasps are in the order Hymenoptera, shared with bees and ants. They often have a bad reputation due to a few particularly aggressive social wasp species that most of us have likely had an unfortunate interaction with. That being said, the wasp group is extremely large, diverse, and species-rich. With over 103,000 described species in the category (and scientist estimates stating that the actual number could be in the millions), wasps span a lot of crucial categories of beneficials including parasitoids, predators, and pollinators.

Many wasp species resemble bees and it can be easy to confuse them for each other when they are visiting flowers. The major differences between the two are the thread-like waist that wasps have, and their less-hairy sometimes shiny, overall appearance. In addition most wasp species are primarily carnivorous, feeding on insects and other sources of meat for their protein needs, making them a great resource for deterring common garden pests (stay tuned for more on that in the next part of the Underrated Beneficials series). Even though most of these wasps are carnivorous, they supplement their diet with sugars which they often get from nectar or honeydew produced by sap-sucking insects, e.g., aphids, and occasionally fruit.

White-Striped Black Mason Wasps ( *Pseudodynerus quadisectus* ) mating on a Goldenrod (*Solidago* sp.) Photo: Abiya Saeed

There are also some species of vegetarian wasps. A common example of these are the 300 species of pollen wasps (Masarinae) which, like bees, are nectar and pollen feeders (and many of which are important pollinators of certain plant species, such as the Water Leaf, Hydrophyllaceae). Due to the fact that they have fewer hairs, wasps aren’t as efficient at pollination as bees, however, they can still be very important pollinators. Like bees, some wasps are generalist pollinators, visiting a wide-array of flowering plants, while others are specialists where a group of wasps relies on a group of flowering plants and vice versa. In these cases the pollination of those plants are reliant on these wasps.

Studies have shown that some generalist wasp species are better than some generalist bees at pollinating specific flowers. A 2018 study by Thomson examining the pollinators of the California Bee Plant (Scrophularia californica) showed that the western yellowjacket (Vespula pensylvanica) was a more effective pollinator in terms of pollen deposition when compared with honey bees and bumble bees. Some species of African pineapple lilies (Eucomis autumnalis and Eucomis comosa) and African milkweed (Pachycarpus grandifloras) are primarily pollinated by spider-hunting wasps (Pompilidae) in the genus Hemipepsis. Additionally over 100 species of orchids are reliant on wasps for pollination some of which use sexual mimicry to attract male wasps to flowers! And I would be remiss if I didn’t mention fig wasps (family: Agaonidae), who have been coevolving with their host plant for tens of millions of years. The fig (Ficus sp.) ‘fruit’ is actually an inflorescence (an enlarged stem with lots of little flowers inside). In order to pollinate those flowers, the female fig wasp squeezes into a small opening and moves around, laying her eggs in the ovaries of these flowers thereby spreading pollen from the fig that she was born in. The male offspring will remain in the fig while the new batch of females will emerge and look for a new fig in which to lay their eggs (see resources for more on this fascinating mutualism).

For more information on wasps as pollinators, check out the awesome article by Hooks and Espíndola, linked in the resources!

Fun fact: Sexual mimicry is used by some flowers to attract their pollinators. In these situations, the flowers use a combination of visual and chemical cues including mimicking the scent of specific female wasps and bees to attract males. An example of this can be seen in the wasp family Thynnidae, where male winged-wasps are searching for wingless females to mate with. When they stumble across the warty hammer orchid (Drakaea livida) they confuse it with a female thynnid wasp, because of the similar shape and scent, and try to mate with it. This process results in the pollen being deposited on the abdomen of the male wasp. As he goes to the next orchid in order to mate, the pollen is deposited on the new flower, resulting in pollination.

Beetles

Beetles (order: Coleoptera) are considered to be the largest insect order with over 350,000 described species, which makes up 25% of all known animal species on Earth! Like some of the previously mentioned orders, they include a large diversity of functional groups, including pollinators. Due to the incredible size of this order, they are considered to be the largest and most diverse group of pollinators with an estimated 77,000 flower-visiting species. In fact, based on pollen-covered specimens preserved in amber from 100 million years ago which is 30 million years earlier than the first records of bee pollinators, beetles are considered to be the first recorded insect pollinators! Even now they are considered to be vital pollinators of some of the most primitive flowering plant groups that still exist today, such as Magnolias.

Flower Longhorn Beetle (*Analeptura lineola*) on a Multiflora Rose (*Rosa multiflora*). Photo: **Ansel Oommen, Bugwood.org**

Although some beetles are specialists of certain plant groups ,especially those that are descendants of some of the earliest flowering plant groups including water lilies and magnolias, most are generalist pollinators and will visit a wide array of flowering plants. Some scientists even estimate that flower-visiting beetle species will visit 90% of all 350,000 flowering plant species. Beetle pollination is also essential for certain agricultural crops including Paw Paw (Asimina sp.) and the Atemoya (Annona x Atemoya).

For more information on the fascinating world of beetle pollination, check out the awesome article by Hooks and Espíndola, linked in the resources!

Fun fact: The process of cross-pollination that depends on beetles is referred to as ‘cantharophily’.

Resources

Cook et al. (2020). The Role of Flies as Pollinators of Horticultural Crops: An Australian Case Study with Worldwide Relevance. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7349676/

Anderson et al. (2023). Marvellous moths! Pollen deposition rate of bramble (Rubus futicosus L. agg.) is greater at night than day. https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0281810

Hooks and Espíndola. (2017). Wasps, surprisingly cool pollinators. https://blog.umd.edu/agronomynews/2020/08/31/wasps-surprisingly-cool-pollinators/

The story of the fig and its wasp. https://www.esa.org/esablog/2011/05/20/the-story-of-the-fig-and-its-wasp/

Hooks and Espíndola. (2017). Beetles and Pollination.
https://blog.umd.edu/agronomynews/2020/06/29/beetles-and-pollination/

The Fascinating Phenomenon of Fasciation

You may have seen it on the odd flower or plant here and there or you may be intentionally growing plants that show this unique and uncommon phenomenon. Fasciation (not fascination- though it certainly is pretty fascinating) is a malformation or abnormal pattern of growth in the apical meristem (growing tip) of plants. The apical meristem is undifferentiated tissue that triggers the growth of new cells (which extends roots and shoots, and gives rise to stems, leaves, and reproductive structures). In the case of fasciation (which originates from the Latin ‘fascia’ which means ‘band’ or ‘bundle’), this new growth is abnormal and often appears as flattening, ribboning, swelling, fusion, or elongation of plant parts. Sometimes referred to as ‘cresting’, this can occur anywhere on the plant but is more likely to be seen in stems, flowers, and fruit. You might encounter this as several stems growing together, a multi-headed or misshapen flower, perpendicular or irregular growth, dense tuft-like growth, or coiled, contorted, and twisted stems which can sometimes have an unusually high concentration of leaves and flower buds.

A fasciated hinoki false cypress ( *Chamaecyparis* *obtusa* ) (Photo: **Anton Baudoin, Virginia Polytechnic Institute and State University, Bugwood.org** )

There are multiple patterns of fasciation that can be observed, including: linear fasciation (which results in the more common flattened and ribbon-shaped stems), bifurcated fasciation (when a linear fasciation splits in two to form a “Y” shape), multiradiate fasciation (where the stems split into three or more short branches, referred to as a ‘witches’ broom’), or the rare ring fasciation (where the growing point folds over to form a hollow shoot) (Geneve, 1990).

A ribbon of fasciated stems (Photo: **Joy Viola, Northeastern University, Bugwood.org** )

Fasciation is a symptom that can be caused by a variety of different factors including genetics, hormones, pathogens (including bacteria, viruses, and phytoplasmas), injury (including chemical, mechanical, and feeding damage), nutrient deficiency, or environmental causes (such as temperature extremes) though in many cases it is still not completely understood and the exact cause may not be apparent in a specific fasciated plant. The stability of this phenomenon is also pretty variable. Some plants can pass on this trait through their seeds (resulting in a genetic likelihood of expressing this symptom), while other plants can develop fasciation (through a variety of causes) and then resume normal growth from a fasciated point, or perennial plants that appear fasciated one year may be completely normal the next year. Scientists have even identified some of the specific genes in which mutation can cause fasciation and have experimentally reproduced this result in seedlings that were exposed to radiation, chemical mutagens, and high temperatures.

Fasciated Gaillardia showing unusual growth in the stems and flowers (Photo: **Department of Plant Pathology , North Carolina State University, Bugwood.org** )

Most often fasciation is just an aesthetic anomaly, is fairly uncommon, and rarely impacts the survival of affected plants (especially if they are established woody plants). In cases of fasciation due to infection by certain pathogens (such as the bacterium Rhodococcus fascians), it is possible for affected plant parts to die prematurely. Although infectious fasciation can spread to other susceptible plants, in the majority of cases fasciation is not infectious and will not spread.

Fasciated asparagus (Photo: **Mary Ann Hansen, Virginia Polytechnic Institute and State University, Bugwood.org** )

Although fasciation can occur on any plant (and has been documented in hundreds of plant species) it is more frequently seen in certain groups such as cacti, daisies, asters, legumes, willows, and plants in the rose family (Rosaceae). It is also more common in plants with indeterminate growth.

Crested saguaro cactus (*Carnegiea gigantea*) (Photo: **Joy Viola, Northeastern University, Bugwood.org** )

In some cases, distinct examples of fasciated plants are intentionally selected for their visual appeal and interest. Many times, plants that have a greater propensity for fasciation, or those that can be vegetatively propagated are developed into cultivars that can be sold (and are often a striking addition in any garden). Many of our dwarf conifers, for example, are propagated from witches’ broom cuttings. In addition, some of our large and uniquely shaped tomato varieties, such as beefsteaks, are selected for their fasciated fruit, and many strawberries that have a wider shape or appear to be ‘fused together’ are also fasciated and considered desirable.

Beefsteak tomatoes are a common example of desirable fasciated fruit. (Photo: Lufa Farms, Wikimedia Commons)

Examples of plants that frequently exhibit fasciation, including those with cultivars that you can purchase for your gardens, are ‘cockscomb’ celosia (Celosia argentea var. cristata), ‘fascination’ culver’s root (Veronicastrum virginicum or sibiricum ‘Fascination’), ‘crested’ hens and chicks (Sempervivum spp. var. cristata), and Japanese fantail willow (Salix sachalinensis ‘Sekka’), among others.

Fasciated cockscomb (*Celosia argentea* var. cristata) (Photo: **Julia Scher, Cut Flower Exports of Africa, USDA APHIS PPQ, Bugwood.org** )

If this strange growth is something you don’t enjoy, you can prune out the distorted tissue. Or if you’re like me – you can just marvel at the weird and the wonderful!

Fasciated Yucca flower stalk (Photo: **USDA Forest Service – Rocky Mountain Research Station – Forest Pathology , USDA Forest Service, Bugwood.org** )

Resources

Fascinating Fasciation (Wisconsin Master Gardeners):
https://mastergardener.extension.wisc.edu/files/2015/12/fasciation.pdf

Plant of the Week: Fasciated Plants (University of Arkansas):
https://www.uaex.uada.edu/yard-garden/resource-library/plant-week/fasciated-2-22-08.aspx

The Genetics of Fasciation:
https://trinityssr.files.wordpress.com/2016/06/4th-ape.pdf

Fasciation (University of California IPM)
https://ipm.ucanr.edu/PMG/GARDEN/FLOWERS/DISEASE/fasciation.html

Fascinated with Fasciation (Dr. R. Geneve, 1990, American Horticulturist)
https://ahsgardening.org/wp-content/pdfs/1990-08r.pdf

Buying lady beetles and mantids for your home gardens is probably not the best pest control strategy

Biological control is the use of natural enemies such as predators, parasites/parasitoids, and pathogens of pests in order to suppress or control them. This is a great tool for pest control and we hear about biological control a lot, especially when we talk about IPM (Integrated Pest Management). It usually comes with the classic imagery of a hungry lady beetle (often incorrectly referred to as the lady ”bug”) munching on aphids.

Cartoon of lady beetles munching on aphids by Sara Zimmerman (unearthedcomics.com)

Yes, many lady beetle species are great predators of pest insects…so much so, that the multicolored Asian lady beetle (Harmonia axyridis) was intentionally imported and released in North America in 1916 as a more ‘natural’ way to control common pests. Species of North America’s native convergent lady beetle (Hippodamia convergens) were also collected from their habitat (around 1924) and relocated to agricultural locations within California for aphid control, which showed high success rates.

Another popular insect that comes to mind when we think about biological control is the mighty and charismatic praying mantid (aka praying mantis). These ferocious predators, in the family Mantidae, are beautiful and captivating creatures that even grab the attention of the non-entomologically-inclined. With their large eyes and raptorial front legs, you can’t help but be fascinated by them. Although there are some native species of mantids in North America, the ones you are most likely to come across in your yards and gardens include the European mantid (Mantis religiosa) and the Chinese mantid (Tenodera sinensis). Like their names suggest, these are not native to North America, though they have been here for over a century being both accidentally and intentionally introduced overtime. The Carolina mantis (Stagmomantis carolina) is another mantis that you might come across, especially in the southeastern United States, and this one is native to the Americas, from the southern US to Brazil.

Adult European mantid eating a grasshopper
(Photo: **Whitney Cranshaw, Colorado State University, Bugwood.org** )

The predatory nature and biocontrol successes of some of these insects have given rise to their popularity as a commercial pest control product and resulted in an increased interest in purchasing them. These are widely available online, in nurseries, garden centers, and in several other retail outlets. Often marketed as a “good alternative to pesticides” the intention behind this practice is a positive one: reducing unnecessary pesticide use by incorporating beneficial insects that will help manage pests in the landscape. That being said, like many other simple and catchy solutions to common issues, this may not be the most responsible or effective option for home gardeners to reduce pest populations while still being good stewards of their yard and garden ecosystems.

What are the issues associated with releasing purchased beneficial insects in home gardens?

Introducing populations of species into new ecosystems can have several unintended consequences. This applies to non-native and native species alike. A Washington State University Extension publication by our very own Dr. Linda Chalker Scott and Dr. Michael Bush from the Washington State Department of Agriculture does a great job of summarizing some of the issues. Whether or not they are native or widespread throughout the country and/or continent, not all regions and/or ecosystems may have high numbers of these insects and their introduction could result in competition with other common predatory arthropods and further unintended ecosystem impacts. These insects can also consume beneficial organisms, especially in the case of praying mantids, who are just as likely to feed on any insect they catch including other predators, pests infested by parasitoid wasps, and even pollinators. In some of these insects, cannibalism is also a common survival strategy, especially if resources are scarce.

Adult convergent lady beetle
(Photo: **Kansas Department of Agriculture , Bugwood.org** )

Introducing these insects into new locations can also introduce their pests, including potential parasites and diseases, which could impact previously unaffected populations and even other species of beneficial insects in our home landscapes. This doesn’t even account for the ethics of sourcing some of these insects and the impacts of removing large quantities from their natural habitat.

Does it actually work for controlling yard and garden pests?

One of the first things that happen when you release these purchased insects into your home gardens is that many will simply disperse. That is, if they survive the harsh conditions of sitting on a store shelf in hot temperatures. In fact, to have the most success in releasing them in your gardens, you need to take special care and pay attention to factors including time of day/temperature and the number and type of pest insects available for them to eat. For more detailed information on lady beetle release best practices, see this publication from UCANR.

Commercially available convergent lady beetles (H. convergens) are harvested as adults in a dormant state from their overwintering sites. They have a migratory behavior where they will disperse before they feed and lay eggs. As mentioned in this publication from Cornell University, some commercial insectaries will feed these adult beetles a special diet to reduce this migratory behavior. If you do still plan on purchasing lady beetles, these could be a better option. Even if these beetles don’t disperse once you have released them, you need enough pest insects to make it worthwhile for them to stick around for a little while. Although H. convergens are considered generalist predators that feed on aphids, scales, thrips, other soft-bodied insects, and even pollen and nectar when prey are scarce, their preferred diet is aphids. Unless you have heavy aphid infestations in small areas, it’s probably a waste of money (and lady beetles) to introduce them to your landscape. If you do however have a very heavy infestation of aphids, you need to make sure you have enough lady beetles to do the job properly. Even if you do everything correctly and have ample aphids for them to eat most lady beetles will still fly away after a couple of days. They are unlikely to lay eggs on the plants that they are released on thus requiring subsequent releases to continue managing a concentration of pests.

A group of adult convergent lady beetles
(Photo: **Scott Bauer, USDA Agricultural Research Service, Bugwood.org** )

Mantids, on the other hand, are released as egg cases (ootheca) or newly hatched nymphs from those egg cases. You will often see mantid egg cases available for sale, and if you don’t release them within a day or two of hatching, most of these nymphs will cannibalize each other. You can try to spread them out around your garden, but they will still likely eat any arthropod that they come across and catch (including other beneficial insects). They are also unlikely to stay localized around a specific pest issue, so they’re not really effective pest control agents. More information on mantis releases can be found in this publication from University of New Hampshire.

European mantid egg case (ootheca)
(Photo: **Whitney Cranshaw, Colorado State University, Bugwood.org**)

What is a better alternative to purchasing insects for home gardens?

Encouraging the natural enemies that are already in your yard and garden landscapes (also known as conservation biological control) is the best way to incorporate long-term and effective biocontrol for home gardens. These natural enemies include predatory beetles, lacewings, parasitoid wasps, spiders, and countless others!

Tomato hornworm caterpillar, parasitized by braconid wasps
(Photo: **Gerald Holmes, Strawberry Center, Cal Poly San Luis Obispo, Bugwood.org** )

Sustaining these beneficial critters also means providing a diversity of habitat, including food and shelter for them. Include a variety of flowering plants all season long because these natural enemies will also feed on nectar and pollen in addition to their prey. Let your landscapes be a little ‘wild’ by keeping some leaf litter, rotting wood, dead perennials, and ornamental grasses which provide shelter for overwintering. More information on encouraging insects for biocontrol in home landscapes can be found here.

Another important factor for maintaining beneficial insects in home gardens is to utilize IPM strategies when pest outbreaks do occur and to minimize unnecessary pesticide use, especially pesticides that are broad spectrum, or persist in the environment for long periods. Utilizing cultural controls, barriers, and tolerating a little bit of pest damage is all going to contribute to the long-term health of your home garden ecosystem.

No Mow May: Is it a good idea?

I know what you’re thinking: “No Mow May? But it’s March!” Although spring currently seems like a distant wonder for us here in Montana, many of our warmer states are seeing the signs of spring that get you thinking about, among other things, your lawns (and if you’re a bee enthusiast like myself, you’re also thinking about the early season pollinators that are beginning to emerge in these landscapes).

What is ‘No Mow May’?

No Mow May (or April, or March- depending on where you are) is a movement that was originally made popular through an organization based out of the United Kingdom called Plantlife. The intention behind the campaign is to eliminate mowing your lawn for the month of May, with the goal of creating habitat and floral resources for early-season pollinators. This initiative has since become more and more popular in the United States in addition to other countries, where we see the classic image of a turf lawn speckled with bright yellow dandelions along with signage that says ‘No Mow May’.

Lawns are a staple of American landscaping and one can hardly imagine urban and suburban areas without the iconic image of the green turfgrass yard associated with many homes. We have about 40 million acres of lawn, which accounts for 2% of all the land in the continental US, making lawns the number 1 irrigated crop in the country! The ideal vision of a good lawn has long been a weed-free, monocultural, uniform green space and people spend a lot of time, effort, and money to maintain them in this way. The image of overgrown, non-uniform, unconventional, and weedy lawns have been historically considered to be unattractive, unkempt, and poorly managed. Although more and more people seem to be changing their opinions and preferences for these conventional turfgrass lawns (and we likely need to rethink some of these expectations anyways), most people still have those underlying perceptions.

The idea behind No Mow May is that flowering lawn weeds, if left unmown, would provide food sources for early season pollinators such as newly emerging native bees (with the added benefit of less work in terms of lawn maintenance). The primary targets of this initiative are generally more urban and suburban areas where food sources and habitat for pollinators can be harder to find and spaces where weedy lawns are less tolerated.

Although the intention behind this campaign is a good one, providing food for pollinators, there are some aspects of this initiative that seem to miss the mark.

So let’s get into some of the science!

Is ‘No Mow May’ good for pollinators?

The answer to this question is: yes and no.

Studies have shown that certain common flowering lawn ‘weeds’ can be an important food source for pollinators, especially in urban and suburban areas where other floral resources can be scarce. A paper from the University of Kentucky found 50 species of pollinators, including 37 species of bees, foraging on white clover and dandelion in lawns (Larson et al., 2014). Although white clover is a nutritious source of nectar and pollen for bees, dandelions on the other hand are not very nutritious (with low protein content in their pollen). That being said, bees and other pollinators will still forage on dandelions especially if other floral resources are unavailable at that time. In the ideal world we would have a plethora of floral resources for pollinators which would incorporate an abundance of diverse flowering plants from early spring all the way through the growing season and into the fall. Unfortunately, most urban and suburban spaces do not meet the specifications of this ideal pollinator-friendly world. Dandelions, on the other hand, are pretty universal in these urban areas (and you have likely seen them in many lawns in your neighborhood). Although they are not a great resource, abundant dandelions can fill the gaps of food sources for bees (especially when the alternative is no food). Other lawn ‘weeds’ and bee lawn plants (as you have seen in last year’s blog post) can also support a diversity of pollinator species and can be a great way to offset the lack of pollinator-friendly resources in a turf-only lawn.

An American bumble bee ( *Bombus* *pensylvanicus* ) feeding on white clover (Photo: **B. Merle Shepard, Clemson University, Bugwood.org** )

Research from a pilot project of No Mow May in Appleton Wisconsin evaluated the bee species richness and abundance in properties that participated in the initiative and found a higher species richness and abundance when compared with areas that had been mowed, but this paper was retracted shortly thereafter, so it is difficult to judge the validity of those results.

That being said, if left unmown: your turfgrass will soon outgrow any other flowering lawn weeds which can make them difficult to find for pollinators, and that is if these flowering lawn weeds aren’t smothered by the tall grass altogether. A study conducted in Massachusetts which evaluated the impact of mowing frequency on bee abundance and diversity showed that lawns which were mowed once every 3 weeks had 2.5 times more flowering plants, though lawns which were mowed every 2 weeks had the highest bee abundance, likely due to easier access and visibility of these floral resources in shorter grass (Lerman et al., 2018).

Is ‘No Mow May’ less work?

The answer to this question, as you probably could guess, is also: yes and no (but mostly no).

I am a self-proclaimed ‘lazy gardener’ and am always looking for ways to reduce the amount of effort I need to put into my gardening endeavors. No Mow May claims to be less work for you in the month of May. Although that is true (because the intention is not to mow for a month), it can often result in more long-term effort in trying to reign in your turfgrass in the after-effects. Not to mention the negative impact that this style of management (or lack thereof) can have on your turf itself.

In many places, lawns can grow a foot or more during the month of May. An un-mown lawn can set you back on your lawn maintenance and result in more work for you in the long run . Then when you are trying to get your lawn back on track afterwards- remembering the rule that you should only remove 1/3 of your turf in any given mowing, it could take weeks to get back to a good functional height (which varies depending on the type of grass, but for most of our lawns, it ranges between 2.5-4 inches). Furthermore, most mowers don’t have the capacity to handle a lawn with a 12 inch height. This will result in removing too much of the grass leading to unintended consequences like stress and decline of your lawn, which can also make it more susceptible to pest and disease issues. This will also lead to a large amount of grass clippings which, if left on the lawn, could smother sections of it and result in an unpleasant and patchy lawn.

Unhealthy lawns can also struggle to compete with and leave spaces open for other undesirable invasive plants, including noxious weeds. These can then spread to other areas and have significant ecosystem impacts (and make it even more difficult to get your lawn under control). Following weed management needs could also require the use of herbicides that can have unintended consequences on pollinators and other beneficial insects.

Furthermore, as noted in an article on No Mow May by Iowa State Extension’s Consumer Horticulture Specialist, Aaron Steil: lawns are not actually a natural space, as most lawns are constructed out of non-native grasses, usually for functional purposes, and require quite a bit of maintenance including water and nutrients. Leaving your lawn unmown will not make your lawn a more natural landscape, and it would not be a responsible way to manage these non-native landscape plants.

What you can do instead of No Mow May: Low Mow May!

Based on what we’ve learned so far: lawn weeds can sometimes be an important food source for bees (especially in urbanized areas, where the diversity and availability of floral resources are fewer) and mowing less frequently results in more of these flowering lawn weeds for bees. We also know that slightly higher (though not too high) mowing heights for many lawn turf species make for healthier root systems and make turf more resilient to stress, pests, and disease issues.

If you have flowering lawn weeds and pollinator conservation is your intention, your best bet would be to aim for a sweet spot between the extremes of mowing way too frequently and not mowing at all. Mowing every other week could be a way that you can reduce the amount of time spent mowing and also support urban and suburban pollinators by letting your lawn weeds flower (in addition to maintaining your lawn at the recommended heights for healthy turfgrass).

Even better yet, you can reduce the amount of space in your landscape that is dedicated to a traditional turfgrass lawn and incorporate a flowering groundcover and/or a pollinator garden that hosts an abundant array of diverse floral resources that provide food for bees all season long!

Now that’s something to be buzzing with excitement about!

Less lawn (speckled with clover), more pollinator plants, and habitat! Photo taken at the home of a colleague and scientist on the Wild Bees of Montana project.

Resources

Iowa State University Extension, Aaron Steil: Tips for participating in No Mow May
https://hortnews.extension.iastate.edu/tips-participating-no-mow-may

Larson et al. (2014): Pollinator assemblages on dandelions and white clover in urban and suburban lawns
https://link.springer.com/article/10.1007/s10841-014-9694-9

Lerman et al. (2018): To mow or to mow less: Lawn mowing frequency affects bee abundance and diversity in suburban yards
https://www.sciencedirect.com/science/article/pii/S0006320717306201?via%3Dihub

Washington State University Extension: Lawn Care Basics
https://s3.wp.wsu.edu/uploads/sites/2076/2018/03/C067-Lawn-Care-Basics-16.pdf

Pest Profile: Spotted Lanternfly

We have seen many high-profile examples of insect invasions, and as gardeners, we have probably come across some of these species in our very own landscapes and experienced their impacts first-hand.

If you live in the Eastern part of the United States, you have probably already heard about one of these invasive insect species that is currently wreaking havoc. The Spotted Lanternfly (SLF), Lycorma delicatula, is a 1 inch long planthopper native to China, and has since spread to Japan, South Korea, and the United States. This is a piercing/sucking insect (Order: Hemiptera) that feeds on the phloem of plants and excretes a sweet and sticky product called honeydew. This feeding damage, especially in large populations, can impact the health of certain plant species. Not to mention the nuisance potential, as any objects under infestations of this insect will find themselves coated in a sticky layer of honeydew.

Picture of a pinned adult Spotted Lanternfly (Photo: **Lawrence Barringer, Pennsylvania Department of Agriculture, Bugwood.org** )

It was first detected in Pennsylvania in 2014, and can now be found in several surrounding states including Delaware, Indiana, Maryland, Massachusetts, Michigan, New Jersey, New York, North Carolina, Ohio, Rhode Island, Virginia, and West Virginia, although most states are considered at risk for SLF invasion. Although the insect itself can’t fly long distances, it can be easily spread by moving infested materials and through their egg masses which look fairly nondescript (like a small smear of mud). Several states are currently quarantining this pest, so follow regulatory guidelines by visiting your state’s department of agriculture. Inspect your vehicles and personal effects for the insects and their egg masses (and scrape them off/squish them) especially if you are traveling through these quarantine areas to prevent spreading them to new locations.

Spotted Lanternfly egg mass on the bark of a tree (Photo: **Pennsylvania Department of Agriculture , Bugwood.org** )

This insect has over 100 potential host species, and this wide dietary breadth adds unique challenges to this insect’s pest potential. Its preferred host plant is another invasive species: Tree of Heaven (Ailantis altissima), which is currently widespread in the US and parts of Canada.

A group of Spotted Lanternfly adults (Photo: **Lawrence Barringer, Pennsylvania Department of Agriculture, Bugwood.org** )

SLF can also be problematic for some important fruit crops such as grapes, where it has the potential to reduce fruit yield, impact fruit quality, and potentially reduce hardiness and winter survival. There are also other economically important trees that this insect feeds on, including apple, maple, black walnut, birch, willow, etc.. Feeding damage can stress plants leaving them susceptible to other pests and diseases. If this pest continues to spread it could have significant impacts on the US grape, horticulture, and forestry industries.

Invasive insect species can also have significant impacts on natural ecosystems, and can tip the balance of a well-functioning food web. Adding a pest that often has very few adapted natural enemies, and especially those that can reduce the availability of an important food and shelter source for other native organisms can result in cascading ecological effects that can be difficult to understand and manage.

Photo: https://www.aphis.usda.gov/aphis/resources/pests-diseases/hungry-pests/the-threat/spotted-lanternfly/

It is important to stay vigilant in keeping an eye out for invasive species such as Spotted Lanternfly, so if you see this insect outside of a currently quarantined area, before you squish the bug; take note of where you spotted it and report it!

State-specific reporting guidelines for Spotted Lanternfly can be found here: https://www.aphis.usda.gov/aphis/resources/pests-diseases/hungry-pests/the-threat/spotted-lanternfly/

If you are curious about other current/potential invasive pests in the US (and state specific guidelines for invasive pests) visit: https://www.aphis.usda.gov/aphis/resources/pests-diseases/hungry-pests/pest-tracker

To learn more about this insect, visit: https://ag.umass.edu/landscape/fact-sheets/spotted-lanternfly

You can also reach out for more information to your state department of agriculture, or your local and regional extension offices.

Bee Lawns: What’s all the buzz about?

A bee lawn is a way to benefit pollinators in our landscapes by providing additional floral resources, and often utilizes a mix of low-growing flowering plants in addition to turf species. Although flower gardens also provide flowering plants for pollinators, bee lawns can be multi-functional in their usability for recreational purposes with the added benefit of providing food for bees.

Habitat loss is one of the major factors implicated in the global declines of native bee species. Providing resources utilized by these critical pollinators can assist in mitigating this. Research through University of Minnesota has found 50 species of bees utilizing the flowers in bee lawns.

The purpose of bee lawns includes providing nutritious sources of nectar and pollen for pollinators, especially in urban environments, where these resources can often be scarce and difficult to find. Additional factors include recreational usability, and reducing inputs, e.g., irrigation, nutrients, weed control, and time spent mowing. Flowering plants suited for bee lawns have a variety of common characteristics including: low-growing and flowering heights, perennial life cycles, the ability to persist with turf species, and tolerance of mowing and foot traffic.

An important consideration is that bee lawns don’t necessarily mean weedy lawns or no-maintenance lawns, but instead require different types of management and serve different functions than traditional turfgrass lawns.

Not all bee lawns are created equal, and some work better than others.

Here are some turfgrass species that can work well for bee lawns:

Cool-season turf

A mix of fine fescues (which includes species such as: creeping red fescue, chewings fescue, hard fescue, and sheep fescue) are some of the best options for bee lawns due to reduced needs for inputs including irrigation, fertilizer, and weed controls, in addition to their compatibility with flowering plants. That being said, fine fescues do not tolerate heavy foot traffic, and may not be a suitable option for turf varieties in areas with heavy recreational use.

Kentucky bluegrass (KBG) is another option for bee lawns, though it requires higher maintenance (including more frequent irrigation and fertilizer inputs). KBG is considered an invasive species in some areas so do your homework.

Warm-season turf

Although there is limited research currently available for warm season turfgrasses and their compatibility with flowering plants specifically for bee lawns, certain species require lower inputs and could be a good option.

Centipede grass is a suitable option for a low-maintenance warm season turf species, and has been utilized in studies evaluating early-spring flowering bulbs as part of a lawn ecosystem for pollinators (see resources for more information).

Bermudagrass can also be used with flowering plants, though it has higher input needs than centipede grass. For more detailed information on warm season turfgrass species suitable to your geographic area and their respective input needs, I would encourage you to reach out to your local and regional extension offices.

Here are examples of flowering plants that can work well with turfgrass species:

Dutch white clover (Trifolium repens)

Dutch white clover (often referred to as white clover or clover) is a common occurrence in many lawns. Although some consider this to be a weed, white clover can provide several benefits including its adaptability to many soil types, the ability to withstand some shade and foot traffic, and the added benefit of being able to fix its own nitrogen. Like its name suggests, white clover produces white (and sometimes pink) flowers, and grows to a height of 4-6 inches. In addition to its hardiness, white clover is also an excellent source of forage for bees due to its long bloom time, and the great quality of nectar (high sugar content) and pollen (high protein content).

Dutch white clover flowers in a lawn (Photo: Whitney Cranshaw, Colorado State University, Bugwood.org)

Creeping thyme (Thymus praecox)

Creeping thyme is related to some of our favorite culinary herbs, and produces fragrant purple/pink flowers. It has a low growth habit (<6 inches) and can tolerate some foot traffic. It performs best in well-drained sandy or loamy soils, and is also considered to be drought tolerant and deer-resistant.

Self-heal (Prunella vulgaris ssp. lanceolata)

Self-heal is native to North America, Europe and Asia, and research from University of Minnesota has shown that 95% of the pollinators that visited the flowers were native bee species. It produces purple flowers and does well in a variety of soil types (with the exception of sandy soils) and in sun or partial shade.

Self-heal flowering with turfgrass (Photo: John D. Byrd, Mississippi State University, Bugwood.org)

Common violet (Viola sororia)

Violets are another flower that some consider to be a weed in home lawns. These spring blooming yellow, purple, and white flowers can be a good source of nectar for pollinators such as butterflies and bees. Violets grow to heights of 4-8 inches, and do well in a variety of soil types in addition to sun and shade.

Purple flowers growing in grass — Violets growing in a lawn (Photo: Sarah Eilers, Montana State University)

Other flowers

Additional low-growing flowers could also be great additions to bee lawns, including early spring flowering bulbs that can persist with turfgrass for multiple years, such as crocus and grape hyacinth (Muscari spp.), which have been observed to attract pollinating insects (especially honey bees).

For more information on the regional suitability of flowering plants to incorporate with turfgrass for bee lawns, contact your local extension offices for more information.

University of Minnesota’s Bee Lab has a lot of excellent information on bee lawns, their establishment, and the diversity of bees that visit them:
https://extension.umn.edu/landscape-design/planting-and-maintaining-bee-lawn#turfgrasses-for-bee-lawns-2939360

https://turf.umn.edu/news/if-you-build-it-who-will-come-evaluating-diversity-bees-flowering-lawns

Additional Resources:

https://www.canr.msu.edu/news/consider-a-flowering-bee-lawn-to-help-pollinators

https://extension.psu.edu/the-buzz-about-bee-lawns

Wisdom, M. M., Richardson, M. D., Karcher, D. E., Steinkraus, D. C., & McDonald, G. V. (2019). Flowering persistence and pollinator attraction of early-spring bulbs in warm-season lawns. HortScience, 54(10), 1853-1859.
https://journals.ashs.org/hortsci/view/journals/hortsci/54/10/article-p1853.xml

Larson, J. L., Kesheimer, A. J., & Potter, D. A. (2014). Pollinator assemblages on dandelions and white clover in urban and suburban lawns. Journal of Insect Conservation, 18(5), 863-873.
https://link.springer.com/article/10.1007/s10841-014-9694-9

Creating artificial nesting structures for cavity nesting solitary bees

Pollinators, especially bees, are an important part of our agriculture, economy, and ecosystems. Gardeners are often well-versed in the importance of bees since we get the opportunity to see these incredible animals in action. We enjoy the results of their labor in the form of fruits, “vegetables”, and seeds which feed wildlife and create beauty and interest in our gardens. In North America alone, there is an estimated 4000 species of native bees, and an estimate of over 20,000 species around the world.

Many factors have played a role in bee declines, e.g., habitat loss, pesticide exposure, pest and disease pressures. Yet there are things home gardeners can do to help mitigate some of these effect and maximize the use of their yards and gardens as a ‘bee-friendly’ landscape. Habitat loss/fragmentation is considered to be amongst the most important factors influencing the decline of wild bee. Urbanization, development, agricultural intensification, etc. have also resulted in a reduction of high-quality habitat for these mostly native bee species.

Many gardeners even make room in their landscapes for pollinators by planting a variety of flowers that attract and help sustain their regional bee species. Although we are often well-versed in offering food for bees (in the form of these floral resources), something that can be overlooked in our endeavors of creating ‘bee habitat’ is the fact that we do not always offer them a place to live, or a ‘home’. Accessible nesting habitat for bees is just as important as floral resources and can make these pollinators’ jobs much easier as they make trips from flowers to their nests in order to provision them for their offspring.

Approximately 30% of bee species are above-ground cavity nesting bees most of which are solitary, meaning that a single female bee will do all the work to find a nesting location and provision the nest with nectar and pollen for her offspring to eat after she is gone. This can be quite a cumbersome task and offering suitable nesting habitat in close proximity to flowering plants we curate in our gardens can be a great way to simplify this undertaking for these momma bees.

Although mimicking the conditions of wild bee habitat as it’s found in nature is one of the best ways to offer a more natural nesting experience, urbanized areas with smaller spaces can often make this a difficult endeavor. In these areas where space is limited, artificial nesting structures for cavity nesting wild solitary bees, sometimes referred to as bee hotels and bee boxes, can be a useful tool for some bee species (which include mason bees, leafcutter bees, carder bees, and more). These bee hotels have been gaining popularity over the years and many people have started to jump on trend placing them around their yards and gardens. In the past 10 years, I have seen a huge variety of these nesting structures ranging from simple to very elaborate!

A bee hotel at the Montana State University Horticulture Research Farm (Photo: Abi Saeed)

Even though there is widespread availability of bee hotels for sale, not all of them are equally as effective in being ‘bee friendly’, and some of these can actually be counter-productive to the health and well-being of these pollinators.

Here are some recommended specifications for artificial nesting structures for wild solitary bees:

Materials

Common materials used in effective bee hotels include drilled wooden blocks and trays and cardboard/bamboo tubes in addition to a box to place them all in. You want these boxes to be closed in the back and open in the front with some sort of a sloped roof so water will drip off and not collect around the nesting tubes.

Avoid using plastic materials/containers (and other things that will limit the ventilation of these structures as this can result in greater pest and disease issues). Very dark colored bee hotels, especially in locations with high sun intensity, can get really hot which can kill the bee larvae inside. It is best to use untreated and unpainted wood, cardboard and bamboo.

Depth/width and measurement specifications

One of the most common issues I see with some of these homemade and commercially available bee hotels are the depth and width measurements. Bees have control over the sex of the eggs that they lay and these cavity nesting bee species will organize their nests so that male eggs are laid near the entrance. These males will emerge first. In mason bees, for example, eggs laid further than 3 inches from the entrance are usually female bees. If the nesting structures are too shallow it can affect these sex ratios, resulting in a lower number of female bees. This can affect the local population.

Although there isn’t a perfect formula for all cavity nesting bee species and the size preferences of their nesting tubes, we know that some sizes work better than others. You should experiment with variations of size to cater to the bee species that can potentially utilize these nests.
When drilling your own wooden blocks, drill holes of varying entrance sizes (between 3/32 and 3/8 inches in diameter) and depths (minimum 5-6 inches) into untreated wood blocks or old tree stumps/logs laying around your garden or wood pile. Don’t drill all the way through the wood, leaving one end closed. If you are buying a drilled wooden block-style bee box, make sure that it falls within the range of these depth and width recommendations.

Size recommendations from University of Nebraska-Lincoln Solitary Bee Hotel Publication (G2256)

You can also create bundles of cardboard tubes, bamboo reeds, and bundles of woody and pithy plants that can serve as a nice nesting substrate that bees will nest within and in-between. These bundles should also be placed in a container with a closed end.

Location

Bee hotels should be placed at about 3-5 feet off the ground. The entrance should have direct sunlight for the most of the day, especially early morning sun. This will help these cold-blooded animals heat up and get started on their foraging and nest building activities faster. Placing the entrance facing South or Southeast is a good location for many North American bee hotels. Make sure these are mounted on a sturdy location not be easily swayed or toppled over by the wind. It should also away from areas with a lot of foot traffic, otherwise a busy bee might crash into you as she travels back and forth while building her nest.

The nesting boxes should not be easily accessible by predators and scavengers, such as birds, raccoons, squirrels, and other rodents. Do not place these next to a bird feeder, which could attract other critters and give them easy access to the bee larvae.

Aftercare

Another common error made with bee hotels is forgetting the aftercare involved with these nesting structures. Because these nesting structures create a more ‘artificial’ nesting environment, grouping a large number of nesting locations in a concentrated area creates a different from what bees have historically utilized in areas with large expanses of natural habitat. If left unmanaged these structures can act as refuges for pests and disease which can be detrimental to the bees that nest in them. This can be counterproductive for our efforts to protect and preserve these pollinators. If you are interested in hosting cavity nesting bees in your home gardens year after year I would strongly encourage you to learn more about aftercare

If you do intend to place bee hotels in your home gardens, here are some very basic aftercare tips to follow, in order to keep these structures a safe and useful nesting option for cavity nesting solitary bees in urbanized areas.

– Move the occupied nesting structures of these bee hotels to a safe outdoor location in the fall, such as an unheated shed or garage, to protect overwintering bees from rodents, other scavengers, and harsh winter conditions. You can also keep these in a wire mesh/ventilated container to further protect them from rodents chewing them.

– Adult bees emerge from these tubes in spring and early summer, so these should be placed back outside when spring temperatures warm up to around 50°F (10° C). After bees have emerged, discard/compost used tubes and discard/burn used drilled blocks, so pest and disease pressures don’t build up.

– Refill your nesting box with new tubes, reeds/twigs, and drilled wooden blocks for the next season of bees to use, and enjoy watching the process all over again!

For more detailed information on caring for the bees in nesting boxes, please take a look at the resources below.

Resources:

The ABC’s of Plants for Bees!

A yellow flower with a pollen-covered bee resting on top.

A bee collecting pollen from a Black-eyed Susan (Rudbeckia hirta).

Though it might not seem like it for some of us who are still in the throes of winter and it especially feels like a distant dream as I look outside my window here in Montana, but Spring is right around the corner. Along with this magnificent season filled with new life in our gardens and landscapes our world will soon be buzzing with pollinators as well!

Most gardeners have a basic appreciation for pollinators. We know they are responsible for many things including providing important agricultural and economic services by pollinating many of the crops that we eat and by maintaining the diversity of plant communities (which help feed and house lots of other wildlife who share our space). Although lots of animals are pollinators, including birds, flies, beetles, butterflies, bats, small rodents, and more, bees are the most important of them all! This is because they have branched hairs covering their body which make them extremely efficient at carrying pollen from plant to plant.

Honey bees often get most of the publicity when you think about pollinators, or bees in general. Although they are really important to our agricultural operations they are not native but were brought to North America by colonists in the early 1600s. Some gardeners can even name a few additional types of bees but many may not realize the impressive number of bee species that are native to North America, estimated to be around 4000!

We are also becoming more aware of the fact that many wild and domesticated bees around the world have been undergoing declines over the past few decades of observation- which brings up questions about what we can do to help. The cool thing about this is that we, as gardeners, can have a positive impact on our bees, by thinking about them intentionally as we design and plant our gardens and take care of them throughout the year.

Just like us, bees need a few basic things to survive. They need food, a place to live, and protection from practices that can harm them (such as improper/unnecessary pesticide use). Each of these needs can be an entire blog post of its own, and in fact might be in the coming months, but my goal for this specific post is to introduce you to some of the resources that have regional information for selecting plants for pollinators.

Pink flowers with a large bee collecting nectar from them.

A bumble bee sipping nectar from a ‘Pink Spire’ Summersweet (Clethra alnifolia).

Pollinator Partnership, Xerces Society, National Audubon Society and lots of other educational organizations have a vast array of plant lists available for the pollinator enthusiast (see the resources linked at the end of this post to find an appropriate list of hardy plants adapted to your region). As you select your favorites from these lists there are a few things you should keep in mind to ensure you have the best impact on bees with the plants you select:

Add a mixture of different colors, textures, and sizes of flowering plants to attract the largest diversity of bees. Some bees (like long-horned bees, leafcutter bees, and honey bees) are generalists, which means that they will forage on a variety of different flowers. Others (like squash bees and sunflower bees) are specialists, which means that they will usually stick to plants in certain families, genera, and even species. By incorporating a diversity of plants in your pollinator garden, you can also accommodate a larger diversity of bee species!

We know that native plants are an awesome addition to pollinator gardens (because they are well-adapted, and evolved with the native pollinators of the region). That being said, you don’t have to avoid non-native plants altogether. Recent studies show that native and non-native plantings can have a lot of overlap in pollinators. In addition, non-native and native plants will also attract different types of pollinators so you can mix it up!

Make sure there are flowers throughout the growing season by planting things that will be blooming while bees are continuing to forage. Certain bees are active during certain times of the year when they are collecting pollen and nectar for their nests. Having something flowering throughout the year means that a variety of bees can take advantage of these floral resources. Some of the most critical plants that you can select are those that bloom early and those that continue to flower into the fall as the growing season ends. These early and late season flowers are very important because there are fewer resources available for pollinators during the times that bees are getting started (in the early months of spring) and when certain bee species are getting ready to overwinter in the fall. Having these early and late season flowers means that bees will have a source of food throughout the growing season, not to mention the beautiful blooms that you’ll get to enjoy throughout the year.

Stay away from plants that don’t have nectar/pollen sources (like some modern hybridized flowers) or those that have complicated features (such as double petals) which make it difficult for bees to actually get to the nectar source.

Keep these plants safe for pollinators, don’t spray pesticides on plants that are flowering. Or you can wait until the blooms have gone.

Now, you get to enjoy the fun part of choosing plants that are going to add beauty and benefit for pollinators in your yards and gardens.

Large pink flowers, with a bee resting on the side of the petals. Cactus spines in the background.

A bee resting on a Prickly Pear Cactus flower (Opuntia spp.).

Stay tuned for future posts about pollinators and other beneficial insects in the coming months. If you have questions about specific plants, their suitability or pollinators in general, visit the resources below or contact your local Extension Offices for more information.

Resources:

Pollinator Partnership Planting Guides:
https://www.pollinator.org/guides

Xerces Society Plant Lists:
https://xerces.org/pollinator-conservation/pollinator-friendly-plant-lists

Audubon Society Plant Database:
https://www.audubon.org/native-plants

(Some) Fact Sheets about Gardening for Native Bees:

Seitz, N., vanEngelsdorp, D., & Leonhardt, S. D. (2020). Are native and non‐native pollinator friendly plants equally valuable for native wild bee communities?. Ecology and evolution, 10(23), 12838-12850. https://onlinelibrary.wiley.com/doi/full/10.1002/ece3.6826