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Organic Solution for Tomato Hornworms

A few people in the garden have recently found the tomato hornworm taking big bites out of their tomato plants. They are large (3″-4″ in length) green caterpillars with 8 white stripes on their back.

Considering their large size, they are remarkably good at concealing themselves. They are so good at hiding, in fact, that some gardeners hunt them at night using blacklight because they will glow when exposed to UV light. (and of course, that’s just a cool way to find them ;-)

Although they hide themselves well, their handiwork is easily noticeable. Hornworms strip entire leaves and can consume large sections of a tomato plant quickly. If left unchecked, these king-sized caterpillars can completely devour a tomato plant in a few days.

What is the organic solution?

One of the best ways to handle chewing caterpillars such as the tomato hornworm, the tobacco hornworm or the cabbage looper is to use Dipel. Read more about Dipel here. Dipel contains Bacillus Thuringiensis (BTK) which also comes in a liquid form rather than a powder.

I personally prefer to use a liquid spray that contains BTK but others prefer to use the powder. Either method works well and is very effective against chewing caterpillars. If anyone in the garden needs further information or help applying BTK or Dipel powder, respond to this post or use the contact form on the website. Organic gardening is new to most people at the HPCG so don’t be shy about asking for help. We each share a common and close space with many different gardeners. And none of us wants an infestation of hungry garden pests!

Oh, and one more thing. If you do see a tomato hornworm and it has a batch of white eggs on its back, don’t kill it. Those are the eggs of the braconid wasp which lays its eggs in the hornworm. If the eggs are visible on the back of the hornworm, it will soon die and a new generation of wasps will be available for the rest of the garden. These wasps are the hornworm’s worst enemy and the tomato gardener’s best friend.

John