The cotton industry in the United States is an important part of the national economy, accounting for more than $25 billion in products and services each year and employing more than 200,000 Americans, according to the U.S. Department of Agriculture. For commercial cotton growers, close and frequent monitoring of the crop is essential. Several insects are harmful to cotton plants and can destroy a crop if left unchecked.
Several worms and caterpillars can cause serious damage to cotton plants. In fact, the tobacco budworm and bollworm can cause enough damage to destroy a cotton crop. In the early stages of a worm infestation, the eggs may be visible on the foliage and other parts of the plant. Once the larvae hatch, they begin to feed on the foliage. In the later stages of an infestation, the foliage and bolls on cotton plants can be entirely consumed by the worms.
Other worms that can damage cotton plants include armyworms and cutworms.
Boll weevils are probably the most well-known cotton pests. The insects, which look like beetles and are grayish-brown in color, damage the plants when they lay their larvae. Adult boll weevils actually do little damage to a cotton crop, but when the females lay their eggs it starts a cycle that can cause significant damage. When the eggs develop into larvae, they feed on the plants, causing them to shed their bolls.
Cotton fleahoppers are another insect that can damage cotton plants. These small, yellowish-green colored bugs feed on the plants' anthers and suck the sap from the buds of the leaves. When fleahoppers have infested a cotton crop, the squares of the plants brown and die.
Several types of aphids can damage cotton plants. Two common offenders are the cotton aphid, which is yellow, and the cowpea aphid, which is black with white legs. Cotton plants infested with aphids will have leaves that curl and die. Sometimes, a black mold is visible on the plants. Seedlings with aphid infestation fail to grow and then die.
Other pests that can infest cotton plants but typically cause less damage than those already mentioned include stinkbugs, ants, lady beetles, damsel bugs, assassin bugs and several types of spiders and mites.