Everything You Need to Know About Organic Insect Control and the Tomato Hornworm

The tomato hornworm is a 3 to 4 inch long caterpillar that has been known to strip the leaves off a tomato plant almost overnight.

If you're quiet, you can hear it chewing as it eats dinner.

Larva Of A Moth

This pest is the larva of a moth (moth wingspan is 3 to 4 inches long) and the tomato worm is green with seven or eight white stripes and a black horn protruding from the end of its body. Once you see one, you won't mistake it for anything else.

tomato hornworm
Tomato Hornworm

Adult Hornworm Moth

The adult moth lays her greenish-yellow eggs on the underside of tomato leaves. This pest produces two generations a year and the larva survive on tomatoes, peppers, potatoes and eggplant.

You'll know you have this pest because leaves on your plants will suddenly start to disappear.

tomato hornworm damage
Lots of missing leaves after that big worm gets started

Treating Tomato Hornworm Infestation

Sprays such as Bt and insecticidal soap will work on this pest but the far easier solution is to examine your plant and hand-pick off the pests. There are usually only one or two caterpillars doing all the damage so spraying to kill one or two pests is overkill. Put the captured caterpillars into a can of soapy water or slightly bury them and then stomp the grave.

If you want to dust a longer term control, then use Diatomaceous Earth (source below). This powder is harmless to humans and pets and lasts until it is washed off

Both braconid and trichogramma wasps parasitize the tomato hornworm. Both will lay eggs on the pest and you'll see white cocoons on the back of the pest. You might want to leave the larva alone so the predators can hatch out. (pick a few leaves for it to feed on and put is somewhere away from your plants).

The tomato hornworm is a bothersome pest but as long as you pick the first few worms as soon as you see damage, you won't be bothered by scores of them later in the year.

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Dusting with diatomaceous earth will control this pest

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