Tomato plants attract a wide variety of bugs, some of which are more harmful than others. Depending on the type of pest, insects that attack tomato plants can feed on the roots, stems, plant sap, fruit, buds or leaves. Those pests that specifically eat the tomato plant leaves are just as damaging as the other types of insects, and sometimes also feed on the buds and fruits.
The tiny tomato pinworms make blotched mines in the tomato plant leaves, causing the leaves to fold and webbing them together. The tomato pinworm is yellowish, greenish or grayish, often with purple spots and up to 1/3 inch long. Control tomato pinworm infestations by applying an insecticide like methomyl and abamectin, as well as by destroying the plants after the harvest is finished to kill any over-wintering pinworms.
The vegetable leafminer feeds on the tomato plant leaves, creating tiny mines or holes that are slightly enlarged at one end. These tomato plant pests are bright-yellow, up to 1/10 inch long and maggot-like, with pointed heads. Treat infested tomato plants with a leafminer-specific insecticide, such as abamectin, cyromazine or spinosad.
Hornworms feed on tomato plant leaves, stripping them from the stems. These caterpillar-like pests are green to reddish-brown with seven or eight "V"-shaped marks and black spiracles along each side of their bodies. Hornworms have a red or black horn-like protuberance growing from their rear ends, and their bodies are up to 3 1/2 inches long. Get rid of hornworms by releasing the natural hornworm parasites Trichogramma, Hyposoter exiguae or Bacillus thuringiensis, or spray the tomato plants with esfenvalerate or carbaryl.
Flea beetles chew tiny round holes in the tomato plant leaves. These insects are tiny, black beetles that are about 1/10 inch long and sometimes have a pale-yellow stripe on each wing cover. Flea beetles often jump or hop like fleas when disturbed. To get rid of flea beetles, spraying the tomato plants with an appropriate insecticide, such as carbaryl, dinotefuran, pyrethrin or esfenvalerate.
Colorado Potato Beetle
The 1/2-inch-long Colorado potato beetles feed on the leaves of the tomato plant. These insects are yellowish-brown and oval with five black stripes down each wing cover and black spots behind their heads. Spray infested tomato plants with a recommended insecticide for Colorado potato beetles, such as acetamiprid, dinotefuran or clothianidin.
Cabbage loopers eat the leaf tissues on tomato plants, leaving behind the leaf veins and making the leaves look skeletal. Cabbage loopers are green caterpillars with white stripes, growing up to 1-inch long. These pests have three sets of legs near their heads and three sets of "prolegs." Treat tomato plants with Bacillus thuringiensis or spinosad to control cabbage loopers.
Blister beetles chew on the tomato plants leaves, making the foliage look ragged and stunting its growth. The 4/5-inch-long blister beetles have elongated bodies and distinct heads. These beetles usually have black bodies, sometimes with yellow stripes or edging. To get rid of these pests, apply an insecticide labeled for blister beetles, such as carbaryl, diazinon, permethrin or esfenvalerate.