Tomato Worm

The Tomato Worm - Big, Fat, And Creepy

The tomato worm, also called the tomato horn worm is:  A) green, B) large, C) creepy, D) a pest, E) entertaining, or F) all of the above. The correct answer is F. One might even add the words nearly invisible, as this large worm, actually an insect larva, which can grow to be over 3" long, is nearly impossible to see unless you are actually looking for it, since its green color allows it to blend in perfectly with the foliage of its favorite food plant, the tomato plant.

Big, Green, And Hungry - The tomato worm is to worms as Kermit is to frogs. It is very green, and somewhere between beautiful and ugly in its appearance. The tomato worm is the larva of a very large moth, the Five-Spotted Hawkmoth (Manduca quinquemaculata), a very large brown and gray moth, roughly the size of a hummingbird, and quite striking in appearance. If you see one of these moths on your property and plan to have tomato plants in your garden next year, it would be a good idea to occasionally check for the presence of the tomato worm as the plants are growing. A single tomato worm can practically defoliate a fairly large tomato plant in 2 or 3 days, and will at times even feast on the tomatoes, usually the green ones.

The tomato worm in other words is a pest, and one best removed from a tomato plant, by handpicking if you don't mind that sort of thing, as soon as it is spotted. Since during the day the worm will often hang out on the undersides of leaves, you have to examine plants closely, though occasionally one can be spotted in the act of munching on foliage. Once a tomato worm gets started on a plant it leaves plenty of tell-tale signs in the form of shredded leaves and droppings.

Cocoons, Scary Looking But A Good Thing - A really scary sight can be one of these large creatures covered with little white cocoons. At first glance one might think that the worm is in the process of making little worms. The cocoons however contain larvae of tiny parasitic wasps. A wasp has laid eggs on the worm, cocoons have formed, and the larvae inside are busy feeding on the inside of the worm, eventually killing it. These parasitic wasps,  Braconid and Trichogramma being the two most common species that feast on the worm, are the tomato worm's primary predators, so are the good guys in this story. For the wasp larvae to develop into adult wasps, the tomato worm needs to continue to feed until they are ready to fly away, shortly after which the worm will die. When some gardeners spot a tomato worm covered with these little cocoons, they will capture it, put it in a  jar, and feed it foliage until the wasps hatch out, and then dispose of the worm. Parasitic wasps such as these are a gardeners friend as they help control many insect pests. They're very small and won't sting, so are good to have around.

Science Projects And Worm Fights - Some like to capture a tomato worm, feed it until it forms its own cocoon, and then wait until the attractive Five-Spotted Hawkmoth emerges, a neat science project if one has the patience. Others will capture several tomato worms, place them in a jar with a few leaves, and watch the worm fights. It appears that the tomato worm is a somewhat solitary creature, and at will often act quite aggressively towards its own kind.

Thus we have our large, green, creepy, and somewhat entertaining pest, the tomato worm.