Parasitized Tomato Hornworm

There seems to be an abundance of Hornworms in the garden this year.  A couple of posts ago I discussed picking the pests off of the plants by hand as one way of controlling them.

This morning while picking even more Hornworms off the tomatoes, I came across one that I though you should see. It had been parasitized by a small insect  known as a braconid wasp.

These tiny wasps  fly around the garden looking for likely victims. When they find a suitable host, they sting the caterpillar and lay their eggs inside its body.  The eggs hatch and the larvae feed on the innards the worm.  As the wasp larvae near the pupation stage, they chew through the caterpillar’s skin and spin small white  cocoons made of silk which remain stuck on the surface of their host. The cocoons are sometimes mistaken for eggs by some gardeners.

This Hornworm has 3 or 4 dozen cocoons on its back. Each cocoon contains one wasp that will emerge and begin hunting more caterpillars to parasitize.

Days later the new fully-developed adult wasps will emerge from the cocoons and  fly off to find new caterpillars to parasitize.  Needless to say the caterpillar does not survive the procedure, which is good news for us gardeners.

The adult flying wasp does get hungry but does not eat caterpillars instead it feeds on nectar from flowers

If you find a caterpillar with these cocoons on its body, leave it undisturbed where you found it so that you will have dozens more helpers in the battle against the Tomato Hornworm.


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