Cotton - Thrips
Description
Thrips are among the first pests to hit a cotton crop, attacking tiny plants before the true leaves develop. Their small size allows them to escape casual visual detection, but the crop damage is easily seen and stand ׳ establishment is often affected. Winged forms (adult) and non-winged forms of these tiny insects measure from 1/60 to 1/25 inch long. Their color ranges from yellow to black, including straw color or brown. Adults have two pairs of wings. Thrips attack many kinds of plants in all areas of the country.
Damage
Nymphs and adults suck plant juices from the tender terminals. The first targets of Thrips moving into early cotton are the seed leaves, which become distorted or crinkled. Thrips-damaged cotton seedlings are sometimes called possum-eared cotton. Feeding damage can reduce stands severely enough to force replanting in extreme cases. Thrips feeding also can set back stand maturity. In most cases, seedlings can develop past the first stage of damage. Where feeding punctures are numerous, cotton may be triggered into a period of erratic habit and growth.
Life cycle
Eggs incubate for ca. four days; nymphs molt twice, over a six-day period; pupa develop over a four-day period; the entire cycle from egg to adult last about 14 days. These pests overwinter in the pupal stage in plant debris. They begin reproducing in the early spring in non-cotton host plants, such as grains, early blooming weeds, and legumes. Once their early host plants toughen, Thrips move quickly into cotton fields. In many areas of the cotton belt, Thrips migrate into cotton about the time wheat is cut. When this pest migrates, late planted cotton is one of their chief targets since the crop is tender and offers easy feeding.