Western bean cutworm

Western bean cutworm

Western bean cutworm (WBCW) is a highly damaging late-season pest in corn. As the corn plant grows, the WBCW larvae feed on the pollen when the plant is developing tassels, later on the silk and finally on the developing kernels. Originally found only in Colorado and other Western states, this yield-robbing pest is now found in all the areas highlighted on the map and continues to move east. In fact, WBCW has been found as far east as the Illinois-Indiana state line.

Because the larvae feed on the ear, the treatment threshold is very low – just 8% of infested plants, compared with 25% to 30% for European corn borer. And, once larvae move into the ear, control with insecticides is nearly impossible.

Western bean cutworm moth		Western bean cutworm geography map

 

 

Damage

WBCW feeds on developing ears, directly impacting yields. And, unlike corn earworm, WBCW is not cannibalistic, so each ear may contain multiple larvae. An infestation of several larvae per ear can reduce yields by 30% to 40%.

Feeding can create entry points for other pests and diseases, which may lead to the development of mycotoxins like aflatoxin. These factors can compromise both grain and forage quality.

Western bean cutworm damage