Interesting. I've never had hornworms on my grapes. Thanks for the tip. You can control any type of caterpillar with products containing Bacillus thuringensis - commonly called "Bt". It's a bacteria that only targets caterpillars and is safe to use around edibles, pets, and fish. A similar product is used to control mosquitoes. Look for brand names like Thuricide, etc. Mix and spray on your vines. When the caterpillars eat the leaves containing the bacteria they die. It works better when caterpillars are young and you may need to spray several times during the season to catch new generations.

I should have said the new book has one additional species since I don't know if the extra one is a moth or a butterfly.

'Looks like a skipper - a butterfly - to me. I've read that skippers are more closely related to moths than other butterflies, and I can believe it, because their chrysalides have a lot of silk around them, sort of like a moth's cocoon. Sherry

I just hatched out 9 Luna moth caterpillars in a tupperware tub a few days ago. I did have 23 eggs but only 9 hatched so far lol. I happy I got some though. Hopefully some of them will make it to adult size. I can't wait to see them come out of their cocoons! They are eating Sweet Gum leaves and growing quickly.