I don't know if cabbage loopers like Artichokes, but they would certainly go for Brussels Sprouts, Pak Choi and Chinese Cabbage. There are a variety of caterpillars that eat artichokes and members of the cabbage family. Kevin's advice on Bt above remains valid for all of them. Especially when the caterpillars are young. I usually don't worry much about Painted Lady caterpillars (as on artichokes). They are typically found at the base of a leaf, under a web. The damage you have looks like it came from something else. There are some big grasshoppers out now, too. They could cause damage like that seen on your artichoke. Bt won't work on them.

They lose their appetites when you go out at night with a flashlight and your oldest pruners, snip them in half like I do with the climbing cutworms that damage rhododenron young growth here. You can also get BT, a natural bacterium lethal to caterpillars only and spray with that, won't harm beneficial insects (or birds, pets, etc). "Bacillus thuringiensis variety kurstaki (B.t.k.) is the general purpose material that homeowners buy when they see just the words Bt or Bacillus thuringiensis without the variety name attached. This is the type of Bt that is appropriate for home landscape use to kill caterpillars."

Looking at that picture makes me soooo glad that I decided to do a lot more fennel this year. Last year was my granddaughter's first experience rearing Anise Swallowtail cats in her grade school classroom from cats she found in my yard. Now she is growing her own fennel to do it again this year. I love seeing kids get interested in the butterflies. I would like to start her on some Polyphemus moths too someday. Thanks again for that inspiring picture. What a master piece the butterfly is. Murray

They got mine last year also. I returned from New Zealand and all my azaleas were leafless. They grew new leaves and now are full of flower buds so it didn't really seem to bother them. I am going to keep an eye out this spring and if I see them I think I'll try insecticidal soap. It worked well on the sawflies that were eating my dwarf pines last spring. I think the key is checking daily and catching them early.