Ask the Expert: Erythraeid Mites, Pyrethoids and Moths


September 30, 2014

Photo credit: gailhampshire/Foter/CC BY

Photo credit: gailhampshire/Foter/CC BY

Q: We service a hospital that has what looks like clover mites entering rooms on the third floor. The nearest grass is on the other side of the building, more than 100 yds. away from the affected area. No mites have been found on the two floors below or the floor above. There’s an extension of the second floor with a flat roof adjacent to the affected area. Where do you think the mites are breeding, and what can we do about them? We can’t use pesticides in the interior rooms. J.B., N.Y.

A: I suspect you don’t have clover mites (Bryobia praetiosa). Traveling 100 yds. from the grass would be difficult for that species. You probably have Erythraeid mites. They’re red and commonly feed on springtails and other small insects in damp areas. Flat roofs are a common breeding ground for these mites. Flat roofs, especially those with gravel, contain damp areas that can be ideal breeding sources for springtails and other small insects. Like clover mites, Erythraeid mites leave a red smudge on the wall if you squash them. Once you confirm this is the source, treat the roof with a residual insecticide. Indoors, the hospital staff can wipe up mites with a disinfectant. If the problem returns within a short period of time, roof drainage might need to be improved.

Q: I’m confused about the new pyrethroid label changes. When do these go into effect? When must we stop using pyrethoids the way we used to? J.T., Ark.

A: There’s no date set for complying with the new restrictions. The law states you must follow the label directions on the container of the pesticide you’re using. If your pyrethroid products have the new labels, you must follow the new restrictions. If you have older product with older labels without those restrictions, you can use the product according to the labels on those containers. Some pest management professionals (PMPs) might be tempted to keep old containers and refill them so they have the old label directions without the new restrictions. Don’t even think about it! Regulators will look at your supplier records to determine what you bought when. If you try this trick, you might be caught, and the punitive actions can be substantial.

Q: I’m dealing with a webbing clothes moth infestation in an upscale, 14-story high-rise. Many of these condo units have wool carpets and Oriental rugs. Moth sightings are widespread. I’ve placed pheromone traps in the lobby of each floor. If moths are captured, I place a trap in each unit on that floor. Any units with moths will be serviced. But how should I treat infestations? I know which unit started the infestation, and everything has been removed for treatment, but I want to disturb the other tenants as little as possible. T.S., Ill.

A: Thoroughly inspect each condo unit that has moths in its pheromone trap. Remove and dry clean or discard all infested goods. Check wool carpets. Consider installing an insect growth regulator (IGR) in each condo unit with moths. This will minimize treating with insecticides and eliminate stray infestations.

You can reach Dr. Mampe, an industry consultant, at

Email your questions about insect identification and pest management technologies and techniques to Dr. Mampe at Your questions most likely will be printed and answered in one of Pest Management Professional’s upcoming Ask the Expert columns.

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