A MIGHTY MITE!

By Arthur V. Evans

In the deserts of Africa, Asia, Europe, and North America large velvety red mites appear suddenly after heavy rains. Southwestern United States has at least two species of these amazing mites.

This past July, I came across a lone individual of a giant red velvet mite, Dinothrombium magnificum (LeConte) emerging from its burrow just east of the Patagonia Mountains in southeastern Arizona where it inhabits the Sonoran Desert and adjacent uplands.

Giant red velvet mites are spectacular for several reasons. First, the largest individuals measure in at a whopping one centimeter in length, which makes them the largest mites in the world. They are covered with a thick coat of scarlet hair-like setae. The mite’s bright red color is apparently aposematic in function and serves to warn predators of their bad taste. Entomophagous animals offered giant red velvet mites either rejected the arachnids outright or quickly spit them out.

Although often difficult to find, they are sometimes extremely abundant locally, if only for a few hours at time. For example, after a brief yet intense thunderstorm, a massive emergence of giant red velvet mites was sighted from the air at an altitude of 1500 feet just north of  Tucson. An estimated 3-5 million mites had emerged in an area roughly two acres in size!

The annual emergence of the giant mites is apparently timed to coincide with that of their primary prey, termites. However, their opportunity to gorge themselves on abundant termite reproductives is quite limited. After mating, the termites quickly shed their wings and bury themselves so that they are out of reach of the mite’s predatory embrace. Adult giant red velvet mites spend most of their lives in subterranean burrows in a diapause-like state waiting for a specific set of ecological conditions triggered by summer monsoons.

Resources:

Evans, A.V. 2007. National Wildlife Federation Field Guide to Insects and Spiders of North America. NY: Sterling. 497 pp.

Lighton, J.R.B. and F.D. Duncan. 1995. Standard and exercise metabolism and the dynamics of gas exchange in the giant red velvet mite, Dinothrombium magnificum. Journal of Insect Physiology 41(10): 877-884.

Newell, I.M. and L. Tevis, Jr. 1960. Angelothrombium pandorae n.g., n. sp. (Acari, Trombidiidae), and notes on the biology of the giant red velvet mites. Annals of the Entomological Society of America 53: 293-304.

Tevis, L., Jr. and I.M. Newell. 1962. Studies on the biology and seasonal cycle of the giant red velvet mite, Dinothrombium pandorae (Acari, Trombidiidae). Ecology 43(3): 497-505.

Zhang, Z.-Q. 1998. Biology and ecology of trombidiid mites (Acari, Trombidioidea). Experimental and Applied Acarology 22: 139-155.


© 2010, A.V. Evans

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11 Responses to “A MIGHTY MITE!”

  1. I’ve seen and photographed them here on out property north west of Tucson, but luckily not by the millions. I hope we don’t even have that many termites, but that may be wishful thinking

  2. Incredible post about an amazing arachnid. I would love the opportunity to see one. I am assuming they do not exist in Missouri? I REALLY need to travel to AZ!

    • To my knowledge, giant red velvet mites do not occur outside of Southern California and the Southwest. Mites or not, you really do need to go to Arizona during the summer monsoons!

  3. Art:

    Am very glad you are back to your blog posts…keep up the good work.

    sam

  4. i have seen so good pic.

  5. Today I had 100′s of them here in Morelos, Mexico. We call them Little Angels. I have seen big, medium and little ones today. We go around picking them up sometimes, check them out, and put them back. They don’t bite, they are really soft and silky and amazing to see in person. In India it is believed they are an aphrodisiac, and thus ground into an oil…and that is enough details….hehe, not too good for these gorgeous bugs……..

  6. These little guys are awesome.

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