Entomology and Plant Pathology, Oklahoma State University
127 Noble Research Center, Stillwater, OK74078
Vol. 12, No. 2
Jan 29, 2013
Winter Grain Mite in Wheat
Tom Royer, Extension Entomologist
I have received several calls about winter grain mite (WGM) infestations in wheat. I thought I would review its description, and some control options. Much of this information was published last year, but I have added some additional information regarding which insecticides are effective.
Description: This mite is small (about the 1 mm long) with a dark blue to black body and 4 pair of orange-red legs (left). It also has a small reddish spot on the top of its abdomen that can be seen under magnification. The eggs of WGM are kidney-shaped, and change from clear, to yellow to reddish-orange after several days. They are laid on leaf blades and stems or the roots near the crown. Besides wheat, many grasses serve as host plants, including barley, oats, ryegrass and fescue.
Life Cycle: Winter grain mites complete two generations per year, the first beginning in fall from oversummering eggs and the second from eggs laid in January/February. In all cases, adult mites are females, all of which are capable of laying eggs. The first generation peaked in December/January and the second will peak in March/April. Newly- hatched mites molt 3 times before becoming adults, and take up to 60 days to mature. Adults can live for up to 40 days. Winter grain mites oversummer as eggs. They get their name because they like grains and grasses, and they really don’t like warm