mite comments
Hi folks – I just ran across your site with the mite photos and
questions. Your identifications and responses are generally good, but I can provide some corrections and additional information for you to use as you see fit.
1. Mites on burying beetles. These are as you indicate, phoretic mites in the family Parasitidae, genus Poecilochirus. Species in this genus all have obligate relationships with silphid beetles. Although they will feed on fly eggs, they also feed from the vertebrate carrion as well.
2. Predatory running mites. 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.
3. "More computer loving mites" 3/21/06. This is a "clover mite", Bryobia praetiosa. This is one of the spider mites, but Bryobia species don’t make the silk webs most often associated with this group. Bryobia are plant feeding mites that are rather non-specific and often feed on plants growing in lawns or otherwise around homes. This species is unusual in that it overwinters as adults and seeks out warmer places in the fall. They commonly enter houses or other buildings. The spider mites belong to the order Trombidiformes, like Anystis and Balaustium, and many, like Bryobia, are also red in color. The dark material seen in the photo is ingested plant material. These are harmless to people, but will leave a red mark on the wall if you squish them!
4. Computer loving mites (1/3/06). This is a species in the family Acaridae, genus Tyrophagus. One of the most common mites found in homes or other buildings, Tyrophagus putrescentiae, sometimes called the "mold mite" will feed on a wide range of organic materials. They are white, somewhat oblong in shape, and have long body setae. They can be part of the normal "house dust fauna" and may be a minor source for house dust allergy. They’re fairly desiccation tolerant as mites go.
5. Mites in the pantry (12/16/05). This is probably a predatory mite in the family Laelapidae. Species of Stratiolaelaps and Cosmolaelaps are not uncommon in the "house dust fauna" and eat the other mites.
6. Mites on reptiles and remedy (11/10/05). This is the "snake mite", Ophionyssus natricis (family Macronyssidae). This is a very serious, blood feeding pest of many snakes, especially captive individuals. They can be a mortality factor if the owner lets numbers build up in the enclosure. These mites feed only on blood, but remain off the host unless feeding. They can quickly build up a significant population. Keeping the snake enclosure clean is the best preventative.
7. Unidentified mite, maybe?… (10/07/05). This is a parasitic mite in the family Macronyssidae, genus Ornithonyssus. These are the most common "bird" or "rodent" mites you mention. These are similar to the Ophionyssus mentioned above in living in the nest material and feeding on the host blood. Ornithonyssus sylviarum (the Northern fowl mite), O. bursa (the tropical fowl mite) and O. bacoti (the tropical rat mite) all occur in California; the first two are parasites of a wide variety of birds, the last parasitizes rodents, commonly commensal rats. All readily bite people when the normal host is no longer around. The remedy is to locate the bird nest or get rid of the rat problem.
8. Angelitos – Cool photos of these fascinating mites!
9. Mites on harvester (6/28/05). These are parasitic larvae in the family Erythraeidae, genus Leptus. Leptus species can be found parasitizing a wide variety of arthropods in their larval stage. Post- larvae are predatory.
10. Mites on newborn’s head (6/21/05). Another Ornithonyssus (see above).
11. Culture mites (2/14/05). You’re right that this is a species of Acarus, most likely Acarus siro. This is the most common "cheese mite" infesting cheese produced in traditional operations. As a historical note, this species was the first mite named by Linnaeus!
12. Locust mites on dragonfly (8/7/04). You’re close here. These mites are related to trombidiids, erythraeids and chiggers, but are actually larval water mites in the family Arrenuridae, genus Arrenurus. Water mites have the same life cycle as their terrestrial relatives (i.e. parasitic larva, predatory post-larvae), but the predatory stages are fully aquatic, living in ponds, lakes and streams. Arrenurus species commonly parasitize odonates. Unlike the red larvae, the post-larvae are a beautiful greenish blue, and are good swimmers in ponds & lakes.
Keep up the good work!
All the best! – Barry
So many mites, so little time!
Barry M. OConnor phone: 734-763-4354
Curator & Professor fax: 734-763-4080
Museum of Zoology e-mail: bmoc@umich.edu
University of Michigan
1109 Geddes Ave
Ann Arbor, MI 48109-1079

Wow Barry,
You are our new hero!!! We are thrilled your letter came on the anniversary of Carl Linnaues birth in 1707. We have posted your letter in its entirety at the top of our mite page and will post the appropriate corrections with the appropriate letters when we have a moment. If you do not want your contact information listed on our site, we will remove it at your request. Thanks and have a great day.
Daniel and Lisa Anne