The common garden pest often called the “tomato worm” generates concern due to its large size and intimidating appearance. This creature can rapidly defoliate tomato plants, leading many people to wonder if it poses a physical danger to humans. They often worry that the prominent spike on its tail is a stinger or that the caterpillar is capable of delivering a painful bite. Understanding the true nature of this larva clarifies the safety risks associated with handling this large caterpillar in the garden.
The Safety of Tomato Worms
Despite their alarming size, tomato worms do not bite or sting humans and are harmless to handle. These larvae are not equipped with defensive mechanisms that can penetrate human skin. The small mandibles, or mouthparts, are designed solely for chewing soft plant matter, such as leaves and stems. They lack the strength necessary to break through human skin.
The most noticeable feature is the fleshy projection on the rear end, commonly called the caudal horn. This structure is a harmless, non-venomous appendage, which is not used for stinging or injecting toxins. It is merely a physical ornament that likely serves a purpose in camouflage or to deter predators. The creature is physically incapable of inflicting harm on people.
Identifying the Tomato Hornworm
The pest commonly referred to as the tomato worm is the larval stage of two related species of sphinx moths: the Tomato Hornworm (Manduca quinquemaculata) and the Tobacco Hornworm (Manduca sexta). Both caterpillars are large, growing up to four inches in length when fully mature. Their bright green color allows them to blend in almost perfectly with the foliage of the plants they feed on.
The two species are distinguished by the markings on their bodies and the color of their posterior horn. The Tomato Hornworm features eight white, V-shaped markings along each side of its body and typically has a black or bluish-black horn. Conversely, the Tobacco Hornworm has seven straight, diagonal white stripes and a noticeable red or orange-red horn. Both larvae feed voraciously on plants in the nightshade family, including tomatoes, peppers, and eggplants.
Techniques for Safe Removal
Since the caterpillar is physically harmless, the most effective pest control strategy involves simple manual removal. Gardeners can easily hand-pick the hornworms from their plants, using gloves if desired. Regular inspection of the plants helps locate the camouflaged pests, particularly by looking for chewed leaves and dark green droppings. When searching, look for the larvae on the underside of leaves or along the stems where they are actively feeding.
Once removed, the safest disposal method is dropping the hornworms into a container of soapy water. The soap breaks the surface tension, causing the larvae to drown quickly, which is an environmentally conscious way to manage the pest population. For a long-term approach, attracting natural predators like the beneficial braconid wasp can help. You can recognize a parasitized hornworm by the small, white, rice-like cocoons covering its body.