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Problem: Winter Grain Mites (WGM) -Penthaleus major
Hosts: Kentucky bluegrass, perennial ryegrass, tall fescue and Chewings red fescue
Description: The young mites are reddish-orange but become black with reddish legs in later stages. There is also a dorsal anus surrounded by a reddish-orange spot. This turf pest is unique in that it feeds during the winter to early spring and spends the summer in the egg stage. Damage often appears from January through mid-March and is evidenced by a silvery, scorched appearance to the turf. Mites feed on cloudy days or at night. On sunny days, WGM's can be found on the crown of grass plants or in the thatch layer.
WGM's feed by rasping the leaf surface and sucking up the plant sap released. The silvery effect is caused by the loss of chlorophyll and desiccation. WGM's are not harmed by short periods of sleet, ice, or frozen ground. They actively feed under snow.
Recommendations: Presence of this mite does not necessarily warrant spraying. However, if damage causes the turf to become unsightly, Lambda-cyhalothrin in liquid formulation (Scimitar R ) or wettable powder formulation (Battle R ) are both labeled against mites in general.
References:
1. Destructive Turf Insects, Harry Niemczyk, HDN Books
2. Turfgrass Insects of the United States and Canada, Cornell University Press, pg 26-29
3. Winter Grain Mites, K-State Research and Extension, Entomology Publication MF-2073
Last Update: 04/23/2003
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