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I saw a decimal-sized dot walking on my hand. I wanted to know what this is, so I got it onto some paper and sandwiched below a piece of clear tape so I could keep it in place and photograph it. However it's so small that even with my camera lens almost touching the specimen, I can't get a great photo. It's small, about 0.8mm long, beige or gray or brown with a pattern on the back. It's a little smooshed from the tape so it's hard to tell if it has 6 or 8 legs and is an insect or an arachnid. But hopefully based on the shape, size, and pattern it can be identified.

Location is southern California.

smallspider

smallspider

Update: I now believe this to be a rat mite or bird mite. I'll include some additional photos that were better quality (photos were taken with a close-focus camera, mites were on printer paper underneath Scotch tape, back-lit by an LED light):

rat mite, with ruler for scale

rat mite, partially fed

rat mite

rat mite, unfed

rat mite, fed

rat mite, unfed

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This appears to be a bird mite (or possibly rat mite) in the genus Ornithonyssus of the parasitic family Macronyssidae.

enter image description here

Credit: user Aewills on bugguide.com

Distinguishing between species is difficult.

In fact, according to idtools.org, identification of Mesostigmata to family or lower can usually only be accomplished only if the specimen is an adult female.

Blaine Mathison mentions the following features useful for identifying these mites to lower taxonomic levels under magnification [source: bugguide.com]:

  • chelicerae shape
  • dorsal plate breadth and degree of dorsal coverage
  • spiracle present between legs
  • genitoventral plate width
  • sternal plate shape and presence of setae

You can find existing answers to posts about bird mites on Bio.Stackexchange below:

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It could be a tick nymph. Difficult to tell as you can't see the beak and the front legs very well. Check out this tick identification site:

http://www.tickencounter.org/tick_identification/tick_species

Looks most like the dog tick maybe?

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    $\begingroup$ Thanks. Actually it turned out to probably be a mite, probably a rat mite. I found many more which appeared to be coming from the attic where we have had rats, and when I took more macros they did appear to look like rat or bird mites. I just never got around to updating this with the new info and photos. $\endgroup$ – A L Jul 4 '17 at 23:32

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