I have to confess to a weakness for hummingbird moths and usually sacrifice a single tomato (or flowering tobacco, datura, potato, or even petunia) plant to them. I only see a few grow to full size before they're parasitized, and the feeding of parasites is one kind of control. BT (Thuricide, Dipel) is a bacteria that'll kill off any little caterpillars. It won't work on the big ones, and is you have to buy a new supply of BT every year (the bacteria can die off), so it's really only good for big gardens and committed gardeners (who spray at the right time).