It's always a shock to run out to the vegetable garden and see an entire tomato or pepper plant ruined, or at least heavily eaten, overnight. When that happens, the culprit is usually the tomato hornworm.
Hornworms are the larval stage of hawkmoths. Tomato hornworm, which is common in desert gardens, is the larvae of the 5-spotted hawkmoth. Hawkmoths are also known as hummingbird moths because of their 5-inch wing span and habit of hovering over flowers to feed. Hawkmoths pollinate a wide array of night-flowering perennials and cactus. The adults feed on nectar, and fly at dusk in spring and through the summer after emerging from underground.
Larvae are initially tiny and pale green but grow quickly to the 3-inch hornworm you recognize, with prominent V-shaped stripes, smooth light-green coloring, and horns. What you see is the final, or fifth, larval stage, just before the caterpillar is ready to pupate. It takes about a month from egg-laying to become this munching goliath in our gardens.
Tomato hornworm blends in amazingly well. As large as they are, it takes practice and sometimes luck to find them unless they move. Look under the leaves, along the stems especially on the downward side, to find them. Despite their size, and fierce looking horns, they do not sting or bite, although they can raise up and appear threatening if you touch them. There are generally have 2 generations a year.
Like almost all larvae, tomato hornworms are specialized about their food preferences. They go for the leaves of members of the potato family, including tomato, pepper, eggplant. Until they pupate they don?t move far from where they hatched.
These pests are eating machines when they are growing and can defoliate a small plant in 1 night. To control them, just pick them off and dispatch them with a tool or your boot. However, you should decide how many hornworms you can tolerate so that the hawkmoths of the summer will still be around.