Tomato Horn Worm

 

This pest is very active in late summer and fall. As the worm matures, it can get up to three inches long or longer and be one-half inch in diameter. A caterpillar this size can eat its way through a lot of plant tissue in one night. Most of the time there are only one or two worms present per tomato plant or even in the whole garden. The worm is also very well camouflaged, so it/they are hard to see. Also if they see you first, which is usually the case, they stop feeding and are perfectly still making detection even harder. Killing large worms with insecticide is difficult. I would suggest checking your tomato plants daily, usually in the early morning or in the evening near sundown. The worms tend to be most active at these times of day and at night. When you detect a worm, cut it in half with your garden clipper or cut off the stem on which it is, place it in a plastic bag and put it in the trash.