Yeah they can quickly wipe out a tomato patch.
They have black poop they deposit in little pellets that and the leaves dissapearing are usually the first signs I notice. Then I have to look and scan each plant really closely. I usually pull up a chair and sit and look up and down every leaf and stem looking for them. They blend in easily and you think you would notice these huge fat worms but nope they hide well.
They eat the leaves stems and tomatoes. They eventually turn into moths only after eating most of you plants. Their eggs are deposited into the soil and then hatch out into little worms.
There are tomato and tobacco hornworms. The difference is the color of their little horn.
And no the horn doesnt sting you it just looks mean. LOL
The tobacco hornworm larva (Manduca sexta) is generally green with seven diagonal white lines on the sides and a curved red horn (above). The tomato hornworms (Manduca quinquemaculata) have eight V-shaped marks on each side and their horn is straighter and blue-black in color (below). These "hornworms" are the larvae of hawk or sphinx moths, also known as hummingbird moths. The tobacco hornworm is the most commonly seen of the two, but both can be found in this region and may even be present on the same plant.
http://www.coopext.colostate.edu/4dmg/Pests/tomato.htm
