How Did This Pest Get Its Name?

Editor’s Note: This article was reprinted with permission from Pinto & Associates.

Just the name makes you want to scratch doesn't it? This tiny mite (too small to be seen with the naked eye) is associated with straw, grasses, and grains. It's also sometimes referred to as the hay itch mite, grain itch mite, and straw mattress mite.

But these mites are not feeding on the straw, grasses, or grains. Instead, they are predators on insects that are feeding on these plant materials. The mites feed on the larvae of grain moths and stored product beetles like the sawtoothed grain beetle. Less often, the mites may feed on the larvae of wood-borers or other insects. In fact, straw itch mites are considered to be beneficial.

A number of researchers even proposed using them as biological control agents for the caterpillars of certain meal moths and for control of fire ants. Straw itch mites reproduce rapidly and can build up to large numbers in the right environment.

You may not consider them beneficial if you are the unlucky human (or pet) who comes into contact with them. Their bites produce a skin dermatitis, a rash which can cover large areas of the body. The itchy pustules may take 10-16 hours after exposure to appear and can last several days. In the olden days, these mites were a problem primarily for those threshing straw or harvesting grains, or for those who slept on straw mattresses. There have been cases of 4-H Club kids at county fairs being infested from the straw they were using to bed their animals and on which they were also sleeping.

Today, you are most likely to come in contact with them if you treat bulk stored grain that is infested with the mites and their prey. Grain that has a high moisture level is especially subject to infestation. Straw itch mites are sometimes found in straw mulch, pine needles, or wood mulch used for landscaping. If you're working in infested grain or handling infested mulch, treat your clothes with an insect repellent. Then remove and wash your clothes and take a shower as soon as possible after you leave the site.

The authors are well-known industry consultants and co-owners of Pinto & Associates.