Apparently they're pest of Avocados. That's horrid because I like Guacamole. I like my California rolls.....yummy. Correction: I LOVE my Guacamole and California rolls. And to think that these bastards put that in any sort of jeopardy........I'd like to sacrifice them to Nordic Gods.
Anyway this site has some rather interesting info on their criminal status. This is a rather long ( YAY! ) extract from said site.
Sorry if I bored you to death. :P But that's not my fault. *^^*
Persea mite (family Tetranychidae) is a key pest that occurs in most avocado-growing areas of California except the Central Valley. It is most damaging to Hass, Gwen, and a few other varieties. Esther, Pinkerton, and Reed are of intermediate susceptibility. The Bacon, Fuerte, Lamb Hass, and Zutano varieties are much less affected.
Many ornamentals and weeds also host persea mite. When persea mites were first introduced into California in the early 1990s, individual mites from heavy populations on avocado trees were seen drifting onto leaves of adjacent stone fruit trees, although they did not feed. Since that time, however, populations have been reduced and persea mites have not been observed on stone fruit trees or fruit, and Prunus species are not known to be a host of this mite.
Persea mite develops from an egg through a six-legged larval stage and two eight-legged nymphal stages before becoming an eight-legged adult. Adult females have an oval-shaped body that is slightly flattened and elongated. Females and immatures are yellowish or greenish with two or more small dark blotches on their abdomen.
Old females that have ceased oviposition turn darker green and become somewhat smaller and inactive. Males are smaller than reproductive females. Males are somewhat pear-shaped, slightly flattened, and yellowish with or without small dark spots. Persea mites feed and reproduce mostly beneath webbed patches or silk-covered "nests."
Each female lays about 2 to 4 dozen eggs during her life. Eggs are round, pale yellow, and develop red eye spots as they mature. Egg to adult female development time is about 2 to 3 weeks when temperatures average 77° to 63°F. Generation time can be accurately estimated by monitoring degree-days.
Cool winter temperatures slow persea mite population growth. Mite densities are lowest about March and gradually increase through spring feeding on new leaf flush. Populations generally peak in July and August. Persea mite populations are suppressed, and populations may decline rapidly, when the daily high temperature is 100°F or more on several consecutive days and humidity is low.
There are pictures on Google of them. Once find one that's "worthy" I'll post it.
Good day my minions!