Tomato Leaf Insects Identification

Look for tunnels through the leaves. Many caterpillars bore tunnels, leaving a trail through the leaf. Caterpillars such as the tobacco budworm, tomato fruitworm and tomato pinworm burrow through leaves, stems and buds. The vegetable leafminer, a yellow maggot, makes winding mines through leaves. The tobacco budworm is a slender, green caterpillar slightly smaller than the tomato fruitworm, which are cream colored or yellowish-green. Tomato pinworms are gray to yellow with purple bands on each segment. They do eat leaves, but are more often found in fruit. Adult leafminers are yellow and black flies whose maggots can cause severe defoliation.

Look for holes. Some insects chew irregular holes in leaves as opposed to boring tunnels. These insects include blister beetles, Colorado potato beetle and flea beetles, along with cabbage loopers and tomato hornworms. All are chewers and can cause extensive leaf damage. Blister beetles are black with yellow sides or yellow stripes. Colorado potato beetles are yellowish brown with five black stripes on each wing cover and black spots behind their heads. Flea beetles are small, dark beetles with a single yellow stripe on each wing cover. Cabbage loopers are green caterpillars with white stripes along the length of their bodies. Hornworms are green with spots along each segment and a horn at the tail end of their bodies.

Check for discoloration or deformation. Sap-sucking insects can cause discoloration where they suck the sap out of leaves or deformation where damage causes leaves to roll or curl. Sap-sucking insects include aphids, which can be black, green or pink. Greenhouse and silverleaf whiteflies are tiny (between 0.96 and 1.5mm) moth-like insects that are white to pale yellow and cause tiny brown spots on the undersides of leaves.