What Other Pests Are Harmful to the Cotton Plant Besides the Boll Weevil?

Bollworms

• Bollworms are the most destructive cotton pest after the boll weevil, according to the North Carolina State University agricultural extension. Bollworms are the caterpillar stage of the bollworm moth (Heliothis zea) and the tobacco budworm moth (Heliothis virescens). These insects typically go through four generations per season. The bollworm moth uses corn as the preferred host for the first couple of generations per season, switching to cotton and other crops once the corn matures. The tobacco budworm prefers tobacco plants but will infest cotton if tobacco plants aren't available.

  Bollworms wreak havoc by eating cotton buds, flowers and bolls. They chew their way into the cotton bolls and eat the insides. Partially-eaten bolls fall prey to plant diseases that rot the bolls. Attacks on buds and flowers mean the bolls themselves never form.

Fleahoppers

• Another major cotton pest, said the Texas A&M University extension service website, is the cotton fleahopper (Pseudatomoscelis seriatus), a yellowish-green oval insect that resembles a flea with long antennae. It feeds on plant sap in both larval and adult stages. It attacks leaves and flower buds, causing them to shrivel, die and fall off, leaving the plant with a "blasted" appearance.

Sap Suckers

• There are several pests that damage cotton by piercing or rasping plant tissue to extract the sap. They are considered relatively minor pests under normal conditions. They include the cotton aphid (Aphis gossypii), which shrivels leaves and stunts seedlings. The tarnished plant bug (Lygus lineolaris) sucks sap from buds, flowers and young bolls, causing them to shrivel and drop off the plant. Spider mites (Tetranychus urticae) suck sap from leaves, killing them. Severe infestations can defoliate plants.

Foliage Feeders

• Some pests damage cotton plants by eating holes in the leaves, reducing the photosynthesis surface area vital to plant growth. These insects give leaves an appearance like they were peppered with buckshot, said the Texas A&M extension website. They include the caterpillars of the cabbage looper moth (Trichoplusia ni), and the brown cotton leafworm moth (Acontia dacia). Severe infestations can totally defoliate plants.

Seedling Killers

• Several insect pests attack cotton seedlings, said the N.C. State extension website. Thrips, such as Frankliniella fusca, shrivel seedlings' foliage. Armyworm moth caterpillars, such as Spodoptera ornithogalli, defoliate seedlings. Finally, cutworm moth caterpillars, such as Feltia subterrania, sever seedling stems just above the roots so they can get at the leaves.