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How to identify it
- Adults are metallic brown to black and about the size of a printed period, with pale yellow legs. The front legs are distinctly longer than the other three pairs.[1]
- UC IPM gives the length as about 0.025 inch (0.635 mm) and describes the body as oval and dark red or brown. A hand lens helps.[3]
- Unlike many other mites, the brown wheat mite does not spin webbing. When disturbed, the mites run quickly over the leaf and drop to the ground.[1]
- Eggs sit on soil particles near infested plants. Eggs laid in winter are nearly round and cherry red; eggs laid as spring goes on are white, with a waxy coating and a ruffled cap.[1][2]
Look-alikes
| Look-alike | How to tell them apart |
|---|---|
| Winter grain mite | The winter grain mite is larger, about 0.04 inch, dark bluish black with red-orange legs and a reddish patch on its back. Its front legs are longer than the rest, but less so than on the brown wheat mite, whose legs are pale yellow.[3][4][1] |
| Banks grass mite | The Banks grass mite is the only prominent wheat mite that webs the leaves, while brown wheat mites spin no webbing. Webbing on the leaves points to Banks grass mite.[3][1] |
Where it lives
Kansas State describes it as a common pest of dryland wheat in western Kansas that can be a problem as far east as Manhattan in dry years. Colorado State reports it on the Eastern Plains and notes recent outbreaks in the High Plains of the central United States. UC IPM lists it among the mites of small grains in California, where mites seldom do enough damage to be a concern.[1][2][3]
Biology and life cycle
It is a cool-season mite. It spends the summer in the soil as white eggs that resist heat and drying, and these hatch in the fall when cooler, wetter weather returns.[2][1]
One or two generations can develop in the fall and two or three more in the spring. Activity is highest in late fall and early spring, and numbers usually peak around mid-April.[1]
All adults are female. Each can lay 70 to 90 red winter eggs in about three weeks, which is why outbreaks can build quickly. Red winter eggs hatch after a week or so of warm weather; the white eggs laid later in spring wait until fall. A given female lays only one kind.[1]
The mites feed during the day, most actively around mid-afternoon, and crawl down into the soil at night. They tolerate cold well in the soil, but a beating rain can knock populations down sharply; Colorado State reports quick declines after heavy rains of about 1/3 inch or more.[1][2]
Besides wheat, brown wheat mites can feed on sorghum, onions, fruit trees, carrots, cotton, lettuce, iris, alfalfa and clover.[2]
Damage and signs
- The mites feed on individual leaf cells and leave a fine stippling that is hard to notice at first. They tend to feed at the leaf tips, which dry out and die.[1]
- Injured leaves look silvery at first and then scorched. Badly infested fields look withered, scorched or bronzed, much like drought injury.[3][1][2]
- Problems are worst during drought and in dryland wheat, though irrigated fields can be affected. Damaging populations tend to build where wheat follows wheat, or where volunteer wheat grew on summer fallow, because the mites have food year after year.[1]
Health risk
Kansas State, Colorado State and UC IPM describe it only as a crop pest and mention no risk to people or animals.[1][2][3]
Control
Prevention
Keep plants from drought stress where you can. Stressed grain suffers the most, a timely irrigation usually relieves the problem, and Colorado State calls adequate irrigation the most effective approach. In drought-prone areas, drought-resistant varieties are also recommended.[3][2]
Sanitation
Avoid giving the mites a continuous food supply: damaging populations build in continuous wheat and where volunteer wheat is allowed to grow on summer fallow.[1]
Biological control
Natural enemies include predatory mites (family Phytoseiidae). Insecticide sprays, including those aimed at aphids, can kill these natural enemies and set off spider mite outbreaks, especially in drought.[2][3]
Pesticides
Spraying is rarely the answer. To check a field, shake plants over a sheet of white paper; counts are hard because the mites drop off disturbed leaves. Kansas State says the threshold is not well defined but is estimated at several hundred mites or more per foot of row in early spring, and that plant recovery depends on later rain even after treatment. Adults start laying white eggs by late April, and once white eggs outnumber red ones the population is in decline and chemical control is usually not justified. Acaricides work less well on drought-stressed plants and are not usually warranted during rainy periods.[1][2]
Common questions
- Why does my wheat look scorched after a dry winter?
- Brown wheat mites are one cause. Their feeding first stipples the leaves, then the tips dry out and fields take on a scorched, withered or bronzed look much like drought injury. Shake plants over white paper in the afternoon to check for the tiny dark mites.[1][2]
- Will rain get rid of brown wheat mites?
- Often it helps a lot. A beating rain can sharply reduce populations, and Colorado State reports quick declines after rains of about 1/3 inch or more. Plant recovery also depends on rainfall.[1][2]
- When is it too late to spray for brown wheat mites?
- Adults begin laying the white, oversummering eggs by late April. Once those outnumber the red winter eggs, the population is in decline and chemical control is usually not justified.[1]
Sources
- Kansas State University Department of Entomology, “Brown Wheat Mite (Wheat Pests).” entomology.k-state.edu/extension/crop-protection/wheat/brown-wheat-mite.html (accessed 2026-11-08)
- Colorado State University Agricultural Biology, “Spider mites in wheat and corn.” agsci.colostate.edu/agbio/ipm-pests/spider-mites-in-wheat-and-corn/ (accessed 2026-11-08)
- University of California Statewide IPM Program, “Mites (Pest Management Guidelines: Small Grains).” ipm.ucanr.edu/agriculture/small-grains/mites (accessed 2026-11-08)
- Kansas State University Department of Entomology, “Winter Grain Mite (Wheat Pests).” entomology.k-state.edu/extension/crop-protection/wheat/winter-grain-mite.html (accessed 2026-11-08)
- iNaturalist, “Petrobia latens taxon page (order and family).” www.inaturalist.org/taxa/263179 (accessed 2026-11-08)