Masses of black mites with red legs – Clover mites
We have a large boulder in the front yard that the girls and I like to play on (Sandy bought it for me on my birthday a couple of years ago. She got it at the gravel pit in Hancock. It’s about 6 feet in diameter. I’m very fond of it). It is gradually weathering away, and pieces of it flake off from time to time. A pretty large piece flaked off on September 5, 2010. This exposed hundreds of tiny red-orange eggs (each only about a quarter of a millimeter across) that had been laid in the crevice underneath the flake:
So, eggs. Hard to identify until they hatch, and these had evidently been laid to overwinter and so probably weren’t going to hatch until spring (and, now that they were exposed, probably weren’t going to survive the winter in any case). But, given the tiny size, the best bet was that they were some sort of mite eggs. And the large numbers suggested that whatever had laid them was fantastically common.
My first impulse was to figure, well, I’ve accumulated a bunch of mite photos by now, maybe I should just run these along with actual mites as part of an “Unidentifiable Mite” issue, and clear out some backlog. So I decided to start with these guys, that Sam had found absolutely covering a small rock back on May 31, 2010:
But then, while prepping the photos, I saw that mixed in with the mites (who were about a millimeter long), there were also a number of tiny orange-red eggs.
Oh, sure, it’s circumstantial evidence that probably wouldn’t get a conviction in court, but it’s good enough for me. These mites do seem to go with those eggs. So now I feel like I’m on a roll, and maybe the mites can actually be identified, tying the whole thing up into a nice, neat package and making this whole posting about just one kind of mite after all. Looking at the mites a bit closer, and in spite of the blurriness from blowing up the pictures so much, we see that they have brownish-black bodies, orange-red legs, and the first two legs are much longer than the others:
So, this isn’t much, but is it enough for an ID? After running a google search on “mite, black body, red legs”, and rummaging a bit, it turns out the answer is evidently “Yes!”
These look to be Clover Mites, Bryobia praetiosa. At least, several sites that I’m finding have pictures that are a close match, but Wikipedia (and a few others) show Bryobia praetiosa as being orange mites, and not black mites with orange legs like mine. Maybe there are two color phases. Or maybe Wikipedia is wrong. Or maybe I am. Any of these is quite possible. If this is what they are, then the are evidently one of those species where the females are parthenogenic and there are no males, so they can lay lots and lots and lots of eggs without spending any time on the whole “mating” business.
Anyway, Clover Mites are evidently pests in two ways. First, they live on plant juices, and if they are especially numerous they can damage clover and discolor grass in lawns. Basically giving you a mild case of “lawn mange”, although if the lawn is looked after well their effects generally aren’t too noticeable. Second, they are yet another species that forms hibernation aggregations in the winter, and so they tend to move into houses in numbers given a chance. Being so small, they can easily get through window screens and small crevices. They don’t do any actual harm indoors, though, and so they can simply be vacuumed up. They should not be crushed, because they leave red stains on whatever surface they are crushed on.
And, they look like they are related to velvet mites, and so probably taste horrible. Just in case you were tempted to eat them.
 There’s also some other small brown arthropod off to the right of the eggs. I don’t know what it is. I suspect it is some kind of very small “true bug”, but it might be something else entirely.
 “Mange” is a general term for skin diseases caused by parasitic mites, mostly in mammals. They look kind of like this, only smaller:
The pictures I’ve seen of lawns damaged by clover mites show thinning and bare spots, which is kind of like what happens to the hair in, say, dogs with mange.
 That’s the “mange” or “scabies” mite (Sarcoptes scabei) from Giant Microbes. Sam and Rosie also have an E. coli; a “stomach ache” (Shigella), a “sea sparkle” (Noctiluca), and a “red tide” (Alexandrium tamarense). The stuff at Giant Microbes mostly looks like quite accurate replicas of the real things, aside from the eyes.
 It’s evidently called “scabies” when humans get it, and “mange” when some other animal gets it. Because we’re special, that’s why. It does appear to generally be a different subspecies of mite for each animal, but humans can get at least one kind of mange from dogs, and dogs probably could get scabies from us. But still, it seems to me that mange is mange, and we should call it what it is rather than inventing a new name so that we can delude ourselves into thinking that we don’t share diseases with dogs.
 There are at least two kinds of mange that dogs get, caused by different kinds of mites. The kind I’ve been talking about (the contagious kind) is “sarcoptic mange”. The other kind, “demodectic mange” or “red mange”, is caused by the mite Demodex canis, which pretty much all dogs have in their hair follicles but that generally don’t cause any symptoms. But, if the dog gets old, sick, or otherwise has a compromised immune system the mites can get out of hand and cause obvious hair loss and skin disease.