Entomology and Plant Pathology, Oklahoma State University
127 Noble Research Center, Stillwater, OK74078
Vol. 11, No. 10
Mar 2, 2012
Winter Grain Mite in Wheat
Tom A. Royer, Extension Entomologist
Roger Gribble, Area Extension Agronomist in Enid reported a wheat field that appeared to be damaged by herbicide, but on closer inspection, was heavily infested with winter grain mite (WGM) which is also called the blue oat mite.
Description: This mite is small (about the 1 mm long) with a dark blue to black body and 4 pair of orange-red legs. 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