Predatory nematodes are basically microscopic "worms" that live in the soil and prey on the larval stages of hundreds of pest insects that have a life stage in the soil. You buy predatory nematodes in a powder or liquid suspension which you mix with water, apply to the soil, and water in. There they multiply and spread out attacking the larval stages of many many pest insects. Unlike some pest predators, predatory nematodes won't fly off to someone else's garden.
Its best to apply them in the spring or the fall when the soil is cooler.
I had forgotten I had used predatory nematodes in the past to deal with a stubborn flea problem in a rent house we once had. The house had been repeatedly bombed and the yard was treated by a professional exterminator twice to no avail, but once I sprayed the yard and the carpet indoors with predatory nematodes the flea problem went away. What I didn't know is that predatory nematodes are not just for treating flea problems.
Just a short list of some of the pest insects predatory nematodes prey on includes all kinds of beetles, such as cucumber and potato beetles, Japanese beetles and flea beetles, borers such as corn borers and onion borers, moths such as coddling moths and meal moths, weevils such as corn, and strawberry root weevils, worms such as cabbage worms, corn earworms, and hornworms, in addition to gnats, aphids, fireants, loopers, cockroaches and termites!
Most of everything that is bugging me can be treated with these predatory nematodes. Since I have used them before I have confidence that they will help me again. I am very reluctant to spray anything on my plants that will hurt natural predators such as lady bugs, or that might harm bees, so this fall I am planning to apply predatory nematodes. The plants that are heavily infested now will just be pulled and counted as a loss.
Predatory nematodes are sold in quantities that describe the "millions of nematodes". So you buy them by 3, 4 and 5 million which is just a small container of powder or liquid, which, as I said, you mix with water. They cost about 18 to 20 dollars and can provide protection for years. If you are interested in using predatory nematodes just do a web search and you will find many companies that sell them. This is the link that I think I will buy mine from http://naturescontrol.com/nemavictims.html