Tomato Hornworm – Droppings

Q: My wife has a couple of tomato plants. This evening she noticed some “things” on a leaf of the plant. Could you please take a look and give us any information you might have about them?

A: Somewhere on that plant is a camouflaged tomato hornworm caterpillar who has answered “Nature’s Call” on your leaves.

Hornworms have a voracious appetite. When they grow large, usually by July, one can devour a foot-long tomato leaf in one day.

Small ones are almost impossible to spot. Their green coloration is excellent camouflage against human and animal predators.

Fortunately, there are two insect enemies that have no problem finding tomato hornworms: both are wasps. The tiny braconid wasp lays her eggs on an unlucky hornworm. The immature wasps consume the caterpillar from the inside and then make numerous white cocoons on the creature’s skin. Additionally, the common paper wasp loves to eat small hornworm caterpillars.

To avoid hurting your insect friends, spray or dust an organic garden insecticide containing B.t. (Bacillus thuringiensis) on your plants in early May and every week thereafter. The B.t. is harmless to animals and insects but is fatal to caterpillars.

In this way you’ll have safe control of the worms but won’t endanger your friends, human or otherwise.