Pests of the Tomato Plant

Tomatoes are top choices of gardeners everywhere because they are low maintenance and easy to grow. There are hundreds of varieties of tomatoes that come in all shapes, colors and sizes. Plant your tomatoes in sunny areas in late spring through mid-summer and water them regularly. Tomatoes are susceptible to a wide range of pests. To ensure healthy crops, it is important to identify pests as soon as possible and go on the offensive.

Chewing Pests

Horn worms are green or reddish-brown caterpillars that are 3 to 5 inches long. They chew and strip leaves from the vine, feeding on the upper portions of the plant. Horn worms sometimes eat the tomatoes and leave open wounds on the fruit. Horn worms often leave black or green droppings behind. Cabbage loopers are white-stripped caterpillars that are about 2 inches long and crawl in a looping motion, much like inch worms. They often turn up on the undersides of tomato leaves. They eat the young leaf tissue and leave the veins intact. Cabbage loopers don't cause much damage and rarely attack the fruit. Flea beetles attack in the early part of the season. The beetles are about 1/2-inch long and are encased in a hard shell of jewel-like shades of amber, green, ruby and brown. They eat small, round holes into the leaves. Large groups of flea beetles will destroy an entire leaf. As the plants grow they can withstand large amounts of flea beetle damage and still produce a good crop. Colorado potato beetles are nearly 1/2-inch long and yellow with five black stripes on each wing; they feed primarily on younger crops. They can seriously damage new plants but will not affect the plant once it's past 8 inches in height. The damage does not reduce the plant's yield.

Sap Sucking Pests

Aphids are common pests for many garden plants. Pear shaped and small in size, 1/8 of an inch long, aphids are usually black, green or yellow in color. They feed in colonies and suck the sap from the leaves and stems of the plant, causing the molting of foliage and discoloration of leaves. Aphids leave behind a waste product called honeydew that encourages mold growth. Stink bugs are bright green or brown in color, about 1/5 of an inch in size and are shaped like a shield. Stink bugs pierce fruit and buds and inject them with toxins that kill plant cells. This causes dropping buds and disfiguring of the fruits. Western flower thrips suck sap from leaves and stems of plants, causing leaves to become discolored and drop. They have a 1/25-inch tubular body shape and fringed wings. Thrips are usually various shades of yellow, although some females can be black. These insects sometimes feed on other insects and mites which may be beneficial to your plants. Thrips are not good fliers but can be carried long distances by wind. The greenhouse white fly is a white moth that sucks juices from leaves and steams of plants. They have four wings that appear to have a powdery substance on them and are about a 1/2-inch long. The damage they do to plants causes leaves to turn yellow and drop from the plant. Plants can become stunted and unproductive. Black soot-like mold may appear on tomato plant leaves.

Mining and Boring Pests

Vegetable leafminers are just over 1/2-inch long and have shiny black bodies with bright yellow markings. The leafminer makes "S" shaped mines on plant leaves. Infected leaves are susceptible to invasion of bacterial and fungal diseases. Severe infestations cause leaves to turn brown and appear burned. Tomato pinworms are caterpillars that are 1/2-inch long and have a yellow-green or purple-black body with brown heads. Pinworms make blotchy mines in leaves. They damage stems, buds and fruits by filling them with pin-sized holes and covering them in dark blotches. Tomato fruitworms are caterpillars that are just under 2 inches long and yellow-olive in color. They bore holes into fruits and buds of the tomato plant. Large numbers of fruit may be damaged if left untreated.

Keywords: tomato pests, tomato plants, tomato insects

About this Author

Amy Deemer has been writing since 1992. Her articles on family life and pets have appeared in the family section of "The Herald Standard" newspaper. Deemer has an Associate of Arts degree in liberal studies from Westmoreland Community college.