I can't say that I've noticed a bunch of them this year, but large caterpillar outbreaks seem to run in cycles. These caterpillars have lots of natural predators, so using Bt-k, which won't cause any harm to anything but caterpillars, is a good choice.

You need to know that Bt-k can affect all young caterpillars, so if you happen to have a butterfly garden in which you you've supplied host plants on purpose, this biological product is a no-no.

It's most effective on very young caterpillars, who's entire mission in life is to eat, eat, and eat some more. Good luck with getting them under control!

Thank you so much for your advice. They seem to be slowing down some - I haven't seen nearly as many as I did a few weeks ago. Now just need to work on getting my leaves healthy again :)