I'm going to spell this wrong....
You can buy BT (bactsyllis thurgacide?) at the garden store. BT is safe for everything BUT catapilliars, it's made from an enzyme in chyrstham petals that is toxic to catipilliars but leaves everything else alone, BUT you must spray every leaf, it's most effective when they're small. Hornworm eggs are bright green and are laid in singles on leaves, so you see those, crush as well.
Evan considers it his job to keep them at bay so he can eat his tomatoes.
Note 90% of the time we find the hornworms in the tops of the plants, they look like the underside of a curled leaf. We break off the leaves and put them out for the birds or toss them to the chicks.