DDT was and is the most effective pesticide ever developed. It is all but impossible to purchase or import since the 1972 ban in the US.
This website has the chemical recipe and instructions to make your own, which requires moderate knowledge of chemistry: http://blog.planetpreterist.com/index.php?itemid=2461
My grandfather was a farmer and bought about a dozen 50 lb bags before the 1972 ban. He said it's ban ran most small potato farmers out of business in South Jersey because the "new" presticides were too expensive and nowhere near as effective against the potato beetles.
After he sold his farm he kept a HUGE garden and dusted the whole area with DDT about once every 2 weeks. I never saw a single insect anywhere near the crops- the shit truly is amazing, the "nuclear bomb" of bug killers.
For those of you who've never seen the stuff in action, it is truly amazing. A friend of mine had a vacation cottage in the woods that was over-run with ants which had built a nest under the house. 4 different exterminators sprayed everything they had and nothing even dented the problem. I mixed about a 1/4 cup of DDT in 2 quarts of warm water and used a clean paintbrush to apply the liquid all around the house foundation, inside the kitchen cupboards, and sort of "mopped" the kitchen floor with it.
W/in 2 days the ants were gone for good. The stuff is safe as milk- there was a scientist in the 1950s who used to eat a tablespoon of it a day just to show everyone how safe it was. Its ban was a purely political move made by- YOU GUESSED IT- the world's stupidest and most worthless people: lawyers.