Annette, as far I as figured out for columbines only weapon is Rose Bayer blue bottle insect killer. It is systemic. Everything else works but so so and you have to do it every day almost.

I did a quick google and several sites say that there are BT sprays that will work on inchworms, but I don't know if this is the right time in their life cycle?

Wow, Annette! I'm sorry to hear that! I sowed tons of columbines this year, I too, would be heartbroken! Let us know what happens!

Hmmmm - - you made me go out and check mine. I've had gazillions of inch worms for a week or so now but no one has touched my columbines (thankfully)

Yup, BT definitely works, is only fatal to caterpillars, like the inchworm.

Well dang, I can't use that, then. I have way too many plants that attract butterflies. There's no way I could entice them, only to kill their babies.