In addition to tomatoes, tomato hornworms can cause damage to a variety of different plants that are in the same family as the tomato, including potatoes, eggplants, peppers. Tomato hornworms are sometimes mistaken for tobacco hornworms, which is a related species. The two hornworms can be found in the same place at the same time, and though their names indicate different plants, both are known to attack members of the nightshade family.
The difference between the tomato hornworm and the tobacco hornworm can be determined by the different markings that appear on the caterpillars. The tomato hornworm has v-shaped marks on its back, and the tobacco hornworm's markings are diagonal. Either species can rapidly defoliate a garden plant; in this sense, telling the difference between the two may not be as important as being able to identify the presence of either species for extermination purposes.The tomato hornworm is actually a caterpillar that eventually metamorphoses into the five-spotted hawkmoth. In some cases, other moth species may be commonly referred to as a tomato or tobacco hornworm, including the Carolina sphinx, the larvae of which is the most common tomato hornworm east of the Rocky Mountains in the United States.