There are a lot of great products out there for controlling insect pests without using pesticides. Some of the best include insect diseases or predators which will attack the pest and not beneficial. For example, there are wasps that kill mealybugs and nematodes that attack grubs. Both of these products are pretty effective. That said there are also some products that just don’t work that well. One of them is known as milky spore disease.
Milky spore disease is a bacteria that infects a variety of different scarab beetles – of which the Japanese beetle is one. It isn’t a disease that we imported from Japan – it’s actually one that was found here. Because this disease affects the Japanese beetle and it isn’t a pesticide per se people get very excited about it. The problem is that it just doesn’t work that well. Sure, it will offer some control, but not much. Probably somewhere less than 20%. Furthermore, most people use it in hopes of reducing their adult beetle population, but adult beetles come from all over, perhaps even miles away, so killing the beetles in your soil doesn’t in any way guarantee that you’ll be controlling the adult beetles eating your roses.
Now if you want to encourage your township to try milky spore disease that might work. Spread over larger areas milky spore will have more of an effect for obvious reasons. But placed on one yard, it’s just not going to do that much.