What is it?
Tomato hornworms, Manduca quinquemaculata, are very large caterpillars that have a "horn-like" tail that gives them their name. Large numbers of caterpillars can occur in home gardens and can quickly defoliate plants.
What plants are affected?
Tomato is a preferred host although they have also been found on potato, eggplant, and pepper.
How to prevent it?
Plants should be examined at least twice per week during the summer to check for tomato hornworms.
How to control it?
Handpick hornworms from infested plants (this is the most effective means of managing them). Tomato hornworms are fairly easy to find because of their large size.
Tomato Hornworms in Home Gardens - http://goo.gl/rVu8J
Tomato Hornworms - Identifying and Controlling Tomato Hornworm - http://goo.gl/0ijzP
Manduca quinquemaculata - Wikipedia, the free encyclopedia - http://goo.gl/jD5Dc
Caterpillars on Tomatoes? Here's Some Help! - http://goo.gl/dGukK