How to Control Tomato Hornworms
Tomato hornworms are extremely large caterpillars that have eight white “V” shaped markings on their side and a tail that looks like a horn. As large as they are, you would think they would be easy to spot, but they do blend in with your tomato foliage. The hornworm moth is grayish-brown with yellow spots.
I’ve never had too much trouble with hornworms, but I noticed dropping from the hornworm on one of my tomato plants today. The droppings are brownish to green, and quite noticeable. After I noticed the dropping, I started to look for the hornworm, and I found a whopper. I took the hornworm to feed to the chickens, but it was so big that I think they were a little afraid of it. I sliced it up a little and they ate it. Had I let the hornworm continue its’ feeding, it would of defoliated my tomato plant in a matter of days.
How do you control hornworms?
The key of course is identification. You should be checking your plants daily. I do this as I am harvesting each day. Hand picking is a viable strategy because the worms are so large. Typically, anything beyond that is not necessary. You can spray BT or bacillus thuringiensis, which is an organic insecticide specific for caterpillars, but I don’t think it is necessary. A better strategy is to encourage beneficial insects and handpick if needed. Hornworms have a lot of natural predators such as ladybugs, lacewings, and wasps. You can encourage predators by creating predator habitat, which involves growing your plants in a polyculture and providing many flowering plants for nectar at all times of the growing season.
***Update 7-18-2012: I found a hornworm covered in braconid wasp larvae. It is best to let this hornworm be as it is providing habitat for the beneficial wasp larvae. I expect to be hornworm free soon!