What kinds of pesticides kill butterflies?

Any commercial pesticide will kill butterflies, but why would you want to? Butterflies are about one of the most benign insect in the world. Even in large numbers, the damage they do from feeding is usually pretty minimal.

If for some reason you need to spray for them, use nicotine tea. (take a pouch of the cheapest chewing tobacco you can find, boil two quarts of water, steep the tobacco in the water for an hour. When it cools, filter the water through a coffee filter, and pour into a garden sprayer. Keep in mind that nicotine tea will kill all insects, the beneficial and nuisance insects as well.)