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Tomato Hornworm

Closer Look Of The Tomato HornwormThe largest caterpillar (worm) that attacks the leaves of tomatoes, causing extensive damage, low yields and stunted growth. This four inch long green caterpillar has white diagonal strips along each side and a prominent ‘horn’ that projects from its rear end. If the horn is black, it is the tomato hornworm; if red, it is the tobacco hornworm, a close cousin. The caterpillar will not ‘sting’ you with its horn, but does wave it occasionally to scare off predators. Being able to consume several tomato leaves in a single day, this insect has a voracious appetite, and a crew of them can wipe out your tomato plants in a week. This is one nasty bug!


Tomato Hornwrom Adult

A large, rather spectacular sphinx moth, with a wingspan of four to five inches, usually with yellow and white markings, others with orange spots. It emerges from the ground in spring, lays a single egg on the undersides of leaves and soon dies. They are sometimes known as hummingbird or hawk moths because of their large size and the fact that they feed like a hummingbird. They normally fly only at twilight, which is why most gardeners don’t see them during the day. In northern climates, there is only one generation of moths, but in southern zones, two are more common.


Tomato Hornworm EggThe greenish yellow eggs are deposited singly on the underside of leaves and hatch in about a week. The young larvae feed for about a month, devouring as many tomato leaves, and sometimes the fruit, as they can. In northern climates, only one generation of eggs are hatched, but each caterpillar, being quite large, can cause considerable damage to leaf structures. Because only a single egg is laid, it is virtually impossible to find the egg, so don’t bother looking for them.


Tomato Hornworm Larvae

The larvae (caterpillar) of the tomato hornworm are light or dark green, with a black horn at its rear, somewhere between 3” to 4” long when fully grown. They are very difficult to see, as they blend in with the local forage quite well. The caterpillars feed for about a month, and then drop to the ground and form a pupa to hibernate. These caterpillars can destroy your entire crop of tomatoes, and are a serious threat to your garden.


Tomato Hornworm PupaAfter about a month the caterpillars fall to the ground, burrow down several inches and form a brown, spindle-shaped two inch long hard shelled pupa. They can overwinter in this pupa state and, in spring (May or June) they emerge from the shell and crawl to the surface as a moth. Their life cycle then begins anew.

Vegetables That Tomato Hornworms Like To Eat

Dill Peppers Potatoes Tomatoes


Bill's catepillar pickerHandpicking for the small garden is probably the easiest method to employ, this being due to the large size of the caterpillars and the normally small number of them. Use Bill’s caterpillar picker (shown at left) if you don’t want to touch them.

BT, if used when the caterpillars are very young, is said to be very effective.

Use mix #2 or mix #18.

Dill is said to make an excellent trap crop, while borage, opal basil and marigolds serve as repellent plants.

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