Floating row covers might be the best way to prevent them from laying their eggs, but you'd have to use them from the early spring on. This year might be a bust for your collards :-(.

If I were you, I would avoid growing any related crops for a couple of years, to let the current crop of pests complete their life cycle and move on. Then you can grow them under the floating row covers from day one and that ought to control them. Or, if you have an available area somewhat removed from your current collard growing area, you could plant there next year, and use the row covers. Let the infested area grow something else for now.

BP

thanks BP for your response. I expected that that would be the case. How disappointing! Our lizard (who loves collards!) will be even more disappointed! I guess we'll give them up for a few years and try again later.

happy gardening!
lynda