A couple weeks ago a story was circulating on social media about oak mites in the Cleveland area. Reports indicated that people were being bitten by the mites and that the bites could cause startling skin reactions. It sparked quite a bit of discussion and concern in social circles, giving me the inspiration to write about the tiny critters.
The oak leaf itch mite (pictured below), Pyemotes herfsi, is a mite that primarily feeds on midge flies. Midge flies create galls (also pictured below) on the margins of oak leaves, where their larvae feed and grow. The mites colonize the galls and feed on the larvae. This feeding pattern makes the oak mite preferential to oak trees, particularly pin oaks and red oaks. The mites are so tiny that they cannot be seen by the naked eye. The interaction between oak mites and humans occurs when a person comes near an infested oak tree. The mites may fall from the tree’s canopy or be blown from the tree by the wind, inadvertently landing on a passerby. Then mites may accidently bite the person. Humans are not a host for these mites. They will not colonize in homes or cars or on pets.
The oak mite’s bite can produce an itchy, swollen, and red rash that may be accompanied by small raised bumps. The bites themselves do not leave lasting damage, but itching the irritating rash could lead to a secondary bacterial infection. Therefore, calamine lotions and hydrocortisone creams are often recommended to reduce inflammation and itching.
The mites are most active in late summer and into the fall. Most people encounter them while raking leaves. Controlling the mite population is difficult and rarely accomplished, because the mites find protection within the leaf galls created by the midge flies. The best way to avoid the mites is to limit time near infested trees, launder clothes, and shower promptly after working near the tree.
There have been reports of the oak leaf itch mites in the Southeastern Ohio region, but there is no need to panic. They mite populations will begin to die off with the first frost. In addition, the midge flies and the mites rarely have a detrimental impact on the overall health of oak trees in the landscape.