Red-Headed Flea Beetle in Soybeans and Corn (07/15/21)
There have been several calls, emails, and texts about the red-headed flea beetle (Systena frontalis) causing defoliation in soybeans and in corn. The beetles also will clip silks of corn. The red-headed flea beetle is about 1/6 inch long and dark black with a reddish head and readily hops around. It feeds on over 40 different host plants including cabbage, beans, beets, corn, alfalfa, potatoes, nursery crops, cranberry and many weed species. It overwinters in the egg stage in the soil. Eggs hatch in June and larvae feed on the roots. Larvae pupate and then adults emerge in July-August and feed on foliage until September. Adults deposit eggs in soil, which overwinter. There is only one generation per year.
The red-headed flea beetle is not typically an economic insect pest in soybeans or corn. Extension reports from other states indicate that the adult stage is readily controlled by foliar insecticides registered in different crops. An action threshold for determining the need for a rescue treatment would be based on percent defoliation and the stage of soybean: 30% in vegetative stages (prebloom), 15% in bloom to pod-fill, and 25% in pod-fill to maturity (unless pod feeding observed). While there isn’t any develop threshold for the red-headed flea beetle in corn, we can use the adult corn rootworm threshold of 25-50% of the plants with clipped silks during pollen shed as to when control would be justified. With the high market value of corn, the lower percentage would be more feasible.
Research Specialist, Extension Entomology