Have you tried the blacklight flashlight trick? The hornworms glow when a blacklight shines on them.

Yes, thanks, that's how we found the two...

BT works great and is organic. By far the best nontoxic garden product (meaning it really works).

Yep, Bt (Bacillus thuringiensis, Thuricide) is your answer. Apply by spraying. Amazing stuff. Works on all caterpillars. You can get it at most any big box hardware store or nursery.

This isn't going to help for this year, but try some companion planting next year. Plant in umbrels like dill, and alyssum. These are for brachonid wasps. They lay their eggs in hornworms and other bad bugs in the garden. Leave some spots in your garden a bit messy with leaves for them to nest in too.

To follow up on Beesneeds good advice, below is a pic of what a hornworm looks like with the wasp eggs attached. If you see one like this it's best to leave it on the plant so the eggs can hatch out ok as they feed on the hornworm.

Would anyone know if I can use mosquito dunks for this project? The first ingredient listed is BT, and I already have them here....how would I go about applying them?

Last year I did this companion planting: one row of tomatoes had marigolds and alyssum ( too crowded) on one side of tomatoes, and peppers on the other side. This row attracted horn worms. The other row of tomatoes with marigolds on one side and basil on the other side did not get the horn worms. So this year I skipped the alyssum and I planted both rows of tomatoes in between a row of marigolds on one side and basil on the other, plus on one side I added some dill as well as borage in between the basil. AND I planted cosmos nearby to support parasitic wasp populations. Haven't found horn worms on the dill / borage side yet, but there are horn worms on the other side with just the basil, marigold and cosmos near the tomatoes

I might be skeptical. Bacillus thuringiensis israelensis (Bti) which is the variety of Bt in a dunk, is allegedly aimed at mosquitos and gnats. Bacillus thuringiensis kurstaki (Btk) is what is conventionally used against caterpillars.

https://gardenerspath.com/how-to/organic/bacillus-thuringiensis/

If you used a blacklight on your plants and didn't find any more caterpillars then there is no reason to spray anything or remove leaves. There are typically only one or two generations per year, depending on where you live.

Rodney

Thank you daninthedirt for mentioning that different types of Bt are meant to target different varieties of insects. I thought they were all the same.

Bt usually isn't marketed by the bacillus strain, though that's always called out on the label if you read the fine print. The regular garden-variety Bt is Kurstaki, and is aimed at caterpillars. I agree that it's confusing. By the same token, Bt isn't really bacteria. It's the toxin produced by that bacteria. The bacteria in your mix has been killed off.

vgkg Z-7 Va, we just found a hornworm with the wasp eggs. You are suggesting to let the horn worm feast on the tomato plant so the wasps can hatch. I don't want to loose the plant though ! Can't I leave the horn worm someplace else ??? Hubby put it all in a plastic box temporarily....

Thank you for your quick response, besneeds ! Can these types of wasps be dangeous to people ? My husband has an allergic reaction to wasp stings....that's why he prefers to drown the worm with the wasp pupae.... whereas I would prefer to have the wasps as our allies in the battle against tomato hornworms...

The wasps are harmless to humans, viable host bodies for their eggs. They could potentially sting if they are squished in your hand, so just don't try to trap and squish them with your hands. They are solitary and prefer to avoid us since we aren't food or hosts and they don't defend nests like larger wasps can be wont to do. In the very rare reports of stings, if there is any reaction to the very weak venom, it's usually localized to irritation of the site. More severe reactions are extremely rare.