A new pest has emerged in the U.S. in recent years: the Oak Leaf Gall Mite, Pyemotes herfsi, also known as an “oak mite” or “itch mite.” The mite’s life cycle and wind-driven dispersal make this arachnid and its painful bites an almost inescapable nuisance.
Where Did the Oak Mite Come From?
This species was first identified in Europe in 1936, where it is probably native. It has since been found in India and Australia, as well as the United States. Although the first incidence of the mite in North America was in 1994 in Kansas City, Kansas, it took an episode in August 2004 to recognize it. Football players from Western Colorado College visiting Pittsburg State University in Pittsburg, Kansas, reported itchy welts after attending a postgame picnic in a local park. Many other victims appeared at nearby clinics and hospitals with similar symptoms, but without having seen an insect bite them. Field trapping by numerous entomologists from several universities and the Centers for Disease Control failed to find a culprit. Ultimately, this search unearthed the 1994 report by retired entomologist Donald Mock that described a similar incident in Kansas City. This report pointed researchers in the right direction: to oak trees.
Although this mite is parasitic on a variety of arthropods, one common host in America is the larva of a tiny fly known as the Oak Gall Midge, which lives in abnormal growths (galls) that it creates on the edges of oak leaves. An adult female mite, bloated with up to 250 offspring, erupts from the gall of its host and gives “live birth.” Males are the first to be “born,” and they wait patiently for their sisters to emerge, mating with them almost immediately. The mated females disperse mostly on the wind. At only 0.2 millimeters (1/125th of an inch), the oak mites are almost invisible to the naked eye, much like other mites. If a breeze carries them onto a human being, they try to feed. The saliva of the mite contains potent enzymes designed to paralyze or kill their hosts. It is this chemical cocktail that causes inflammation.
Oak Mite Bite Symptoms
The typical reaction to bites of the Oak Leaf Gall Mite is the appearance of welts about two centimeters in diameter, with a central vesicle (pustule- or blister-like swelling) that appears 10-16 hours after the painless bite. Scratching can easily lead to secondary infection.
Get Relief With After Bite®
If you are bitten by an Oak Leaf Gall Mite, After Bite® products can be your best friend in alleviating symptoms. Please make sure to apply per the label instructions.