Wildlife Watching Wednesday: The Tobacco Hornworm Caterpillar
By: Tom Berg
Gardeners who enjoy growing tomatoes have many things to worry about: are their tomato plants getting enough water? Enough sun? Too much water? Not enough fertilizer? But one thing almost all of these gardeners hate is the tobacco hornworm, sometimes called the tomato worm.
Tobacco hornworms are the larvae, or caterpillar, of the Carolina sphinx moth. Since the adult moths typically only fly at night, they are seldom seen. Even so, the tobacco hornworm is a relatively common garden pest. They are large, green caterpillars that can grow to 3-4 inches in length, with a distinctive spike (or horn) at their posterior.
Tobacco hornworms are often confused with the very similar Tomato Hornworm. Both caterpillars are large and green and have that characteristic spike. The difference is that tobacco hornworms have white diagonal lines on their bodies and a red horn, while tomato hornworms have white V-shaped markings and a black or dark blue horn.
Both species of hornworm feed on tomato plants, often stripping individual branches of leaves almost overnight. Tobacco hornworms sometimes even eat the unripe green tomatoes, leaving large holes or gashes in the fruit. Although tomato plants seem to be the main targets of these pesky hornworms, they also feed on tobacco, pepper, eggplant and potato plants. Some weeds are also on their menu.
Gardeners should inspect their tomato plants every day to make sure none of these hornworms have appeared. Their green color matches the green leaves and stems of the tomato plants perfectly, so they are actually pretty hard to spot. Missing leaves are a dead giveaway that one is present, however, and a careful search usually reveals the culprit.
Luckily, tobacco hornworms (and tomato hornworms) are harmless to humans. They also move very slowly, so they are easy to remove. Simply pick them off of the plants by hand – you can use gloves if you don’t want to touch them. Just drop them in a bucket of soapy water to kill them or cut them in half and put them near your bird feeders. The birds will be happy to eat them!
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