Battling the Tomato Hornworm

Tomato Horn Worm Tomato Horn Worm Photo by perpendicularity.com

Enjoying a delicious tomato sandwich is high on the list of priorities for many of us this summer. As we painstakingly grow and care for our tomato plants, it is only natural to look forward to the reward that comes when we are surrounded by vibrant tomatoes. Though we humans enjoy these tomatoes immensely, we are not the only ones; unfortunately tomatoes are tasty to pests as well.

One pest in particular is driven to consume and destroy the tomatoes we work so hard to produce. That pest is the tomato hornworm. The tomato hornworm is a caterpillar that goes on to become a five-spotted hawkmoth, but it makes plenty of stops at tomato gardens during its life cycle. It is not only tomatoes this creature enjoys, however, as it is more than happy to feast on peppers, potatoes, and eggplant as well.

The tomato hornworm begins its life cycle as a small green egg. This egg is laid on a leaf, hidden on the underside, where it will remain until hatching usually within a week or so into a green caterpillar and growing to be able the size of a finger. This caterpillar has eight white stripes on its body that are placed in a diagonal pattern. Also present are circular markings that are yellow and red in coloration. At the end of their body a horn is present. When it achieves moth form, it will be approximately the size of the palm of your hand, bearing yellow spots on a grayish/brownish body.

In order to grow, this creature will consume tomatoes. Since it is trying to meet growth needs, it will eat continuously throughout the day and night for about a month before burrowing in the soil. The voracious appetite of these critters will therefore make a mess of a tomato garden in very little time, causing the loss of the hard earned tomato sandwiches you’ve been dreaming of eating.

Although the tomato hornworm may eat your tomatoes, the worm itself is eaten by the braconid wasp. The braconid wasp will lay eggs on the tomato hornworm which appear white, fuzzy, and cylindrical. Having braconid wasps is a good thing and any tomato hornworms affected by them should be left alone as the wasp larvae will hatch and move on to parasitize other hornworms, solving the problem of tomato damage for you. If you have tomato hornworms but no assistance is being offered from the braconid wasp, they can be dealt with by handpicking and placing in soapy water or using insecticides such as Bt (Bacillus thuringiensis) which are intended to kill only caterpillars and will cause the tomato hornworm to stop feeding on your plants immediately. It will need to be applied weekly, however, to keep the hornworm in check as new ones pop up.

Though the tomato hookworm can ruin your tomato plans, you can stop it from doing so by being vigilant. Keep a close eye on plants, watching for both the hornworm itself as well as telltale signs of its presence such as fecal droppings or tomato damage. Once you know the problem exists, prepare yourself to tackle it as necessary, with either your hands and soapy water, Bt pesticide, or help from the braconid wasp. Whichever method you use, take back your tomatoes and enjoy them as intended!


Discuss in our forums

1 Comment on Battling the Tomato Hornworm

Leave a comment