Thrips Populations Rise in Kentucky Corn and Soybean Fields

By Blake Jackson

High numbers of thrips have recently been detected in corn and soybean fields across western and central Kentucky, prompting growers to closely monitor crops during critical stages of development.

According to University of Kentucky researchers Dr. Rogerio Lira, Dr. Felipe C. Batista, and Dr. Ric Bessin, the insects are being found as double-crop soybeans emerge and corn enters the ear formation stage.

Thrips typically cause limited direct damage to corn, and most plants recover without affecting final grain yields. However, feeding injuries can increase the risk of disease by creating openings for pathogens, especially during ear development.

In soybean, thrips are also capable of transmitting Soybean Vein Necrosis Virus, making regular field inspections important.

These tiny insects measure only about 1/16 inch long. Young thrips are wingless and yellow, while adults may appear yellow or dark-colored and have narrow, fringed wings. Because of their small size, they are often difficult to spot.

Instead, growers should watch for silver-gray streaking on leaves, black fecal specks, and leaves that become curled or twisted.

Thrips populations tend to increase during hot, dry weather, as drought conditions favor their reproduction. In corn, they are commonly found inside whorls, tassels, ears, or between developing leaves. In soybeans, they are usually concentrated on young foliage.

Routine scouting remains the most effective strategy for managing thrips. There is no established economic threshold for corn because the crop generally outgrows feeding damage.

Insecticide treatments should only be considered during severe infestations that coincide with prolonged drought or other plant stress, particularly in seedlings or during ear formation.

Soybeans also rarely experience economic losses from thrips alone. However, treatment may be justified when more than 75% of sampled leaves show feeding injury and populations average eight thrips per leaf.

Heavy rainfall often reduces thrips numbers naturally. When insecticide applications become necessary, growers should consult their local Extension agent and avoid broad-spectrum products whenever possible to help preserve beneficial insects and reduce the risk of secondary pest outbreaks.

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