Mistaken Identity: Tomato Hornworm or Tobacco Hornworm?
Everyone loves to see their garden growing, but it is disheartening when something else starts eating the garden before the gardener. Even if it is early in your growing season, it is important to spend time in your garden looking for pest insects. If you have ever grown tomatoes then you may have encountered what you thought was a tomato hornworm. This caterpillar is a large green caterpillar that has a distinctive horn on its abdomen. However, there are two caterpillars that look almost the same. Here’s a quick breakdown of which caterpillar you may have in your garden.
Tomato Hornworm, Manduca quinquemaculata (Haworth)
This caterpillar is the larval stage of the sphinx moth or hawk moth. The tomato hornworms feed on anything in the Solanaceae family which includes tomatoes, potatoes, peppers, and eggplants, but is most commonly found on tomatoes. They can reach sizes of several inches and will strip leaves of foliage. The caterpillar is recognized by its green appearance, yellow stripes on the side that form a “V-shape” and a black projection or horn. The moth can be up to 5 inches across and has 5 sets of orange spots on its abdomen. The wings are speckled gray, brown, and black providing excellent camouflage.
Tobacco Horn Worm, Manduca sexta (L.)
The tobacco hornworm also feeds on plants in the Solanaceae family including eggplant, peppers, tomato, and potatoes. This caterpillar reaches similar sizes and the adult is also a large moth. These moths are usually called hawk moths or hummingbird moths. While both of these caterpillars can be found across the United States, the tobacco hornworm is more likely in the SE. The caterpillar is bright green with yellow stripes and a red horn or projection. Both the tobacco hornworm and the tomato hornworm will pupate in the leaf litter before emerging as moths. The adult looks almost identical to the tomato hornworm except it has six sets of orange spots on the abdomen. The last set can be fairly small causing mis-identification.
The easiest way to control both of these caterpillars is to walk through the garden and look for damage. The caterpillar can then be removed from the plant and dispatched. Natural products such as Bt (Bacillus thuringiensis) can also be used. It is specific for caterpillars so make sure it does not drift to larval plants of butterflies.
There are many predators that will also feed on this caterpillar, including wasps and birds. If you
see a caterpillar that looks like it is carrying white eggs on its back you can leave it alone. There are predatory wasps that lay their eggs in the caterpillar that hatch and feed on the inside. Eventually when the larvae are ready to pupate they spin silken cocoons on the back of the caterpillar before emerging. This caterpillar is serving as a host insect and will not survive.
For more information on tobacco hornworms, visit http://entnemdept.ufl.edu/creatures/field/tobacco_hornworm.htm
For more information on tomato hornworms, visit https://edis.ifas.ufl.edu/in1206