Reply #5: Sevin dust is very bad for butterflies

[Lone_Star_Dem]

Also, lady bugs, beneficial mites (the ones that prey on the bad mites), praying mantis, lacewings and all forms of bees, just to mention a few. It's really nasty stuff and should never be used in a butterfly garden.

If you feel you really need to spray an insecticide, I'd suggest a spinosad based product. It will kill the caterpillars, but it's said to be safer on adult butterflies and many other beneficial insects.

Edit to add: I want to suggest not using a spinosad product on a butterfly host plant as it's a sure way to stop the butterfly cycle.