Balaustium Mite

This little red bug.
My Name is David Di Iorio. I ran across your link, and thought I would drop a line to ask a question. I live in central NJ, and on a nice sunny day, these little guys come out from all over. My backyard is 80 % cement, and seem to hang out on the patio and on the steps. But know, this year they are on top of the roof of my garage and appear to be all over. I need to get a handle on this and would like to know if they are harmful. Any information would be good if you can help. Some of the folks at work would like to know also.
Thank you,
David Di Iorio

Hi David,
Our first inclination would have been to say you have Predatory Running Mites, but we just received a very thorough explanation. Here is some information just supplied to us by a real expert named Barry M. OConnor: “All of the mites in the photos you call by this name are species in the family Erythraeidae, genus Balaustium. I think you have these confused with species in the family Anystidae, genus Anystis. Both of these mites are relatively large (for mites!), red in color, and commonly occur in aggregations. Anystis are the very fast moving, predatory mites. Their body is almost circular in outline. They run in what appears to be a random fashion until they encounter small arthropod prey. These are harmless to people. Balaustium, on the other hand, are more elongate as seen in your photos, with a distinct gap between the 2nd and 3rd legs. Species of Erythraeidae have piercing mouthparts and are also predatory on small arthropods or eggs in their post-larval stages, but Balaustium are unusual in being pollen feeders. They can be found in large numbers in flowers, but are most often seen by people on flat surfaces where pollen falls. These mites have been reported to bite people, causing some irritation, although why they do this is uncertain since they’re not parasitic.”