Itch Mites

Hamilton County Public Health is warning about an outbreak of bites from what appears to be pyemotes itch mites. We are currently investigating the incidents. Bites appear to be
consistent with those from microscopic mites. Mites are not known to transmit disease in humans.


What does the bite look like?

The bites generally began with a pimple measuring 2-3 millimeters and within hours or up to 36 hours it becomes the size of a silver dollar, with a clearing in the center. Multiple bites can appear as a red rash. The lesions usually disappear in 10 to 14 days.


What are the symptoms?

Symptoms are generally itching and redness at of the bite location. The bites are typically located on the head, neck, arms and face and can grow in size and also become painful. The bite marks do not resemble markings of MRSA, Lyme Disease and chiggers or bed bugs (in which bites are located mostly on the legs).


What is the cause?

We suspect the cause of these insect bites is itch mites.  The mites cannot be seen and the bites are not felt, but leave itchy red mark that can resemble a skin rash. The mites cannot live on humans, do not survive indoors and are not known to transmit disease.


What if I already have bites?

Those individuals with bites are urged not to scratch, as breaks in the skin can cause an opportunity for bacterial infection. You may also wish to check with your regular healthcare provider for advice on medication that can relieve the itching.


Where do these mites come from?

The microscopic mites prey on the small fly maggots which cause leaf edge galls on tree leaves. When the maggots mature, they emerge from the galls, drop to the ground and pupate for the winter. When the numbers of the gall gnat larvae decline, either through predication or by evacuation from their galls, the hungry mites crawl about on foliage or bail out of  the trees into wind currents to find other suitable hosts.


What prevention measures can I take?

  • The use of insect repellants with DEET may be useful in keeping mites away as well as wearing long sleeves and pants.
  • Keep doors and windows closed to keep mites from blowing indoors. Microscopic mites can easily penetrate screens, so keeping windows and doors closed is also recommended.
  • Avoid walking near heavy woods and vegetation in the evening when mite activity is heaviest and wash the skin once indoors.
  •  When working outdoors, especially is raking leaves,
    1. Wear long sleeves, long pants and a hat
    2. Use insect repellant containing DEET
    3. Avoid direct handling of leaves and lawn clippings
  • Remove clothing items each day and launder them, since mites can remain in the fabric for several days. Take a warm soapy shower soon after coming indoors.


Will spraying trees help?

We do not recommend spraying trees. The mites are completely immune to chemicals when they are inside the gall. Spraying trees is very expensive and rarely will coat all leaves.


Should I cut down my trees?

No, if mites are identified it is not necessary to cut or  remove trees. Mites may not be bothersome every year and do not warrant removal of shade trees that add value to your property.


For more information, please contact the Division of Disease Prevention at 513.946.7887.


Download a printable version of this fact sheet here.


250 William Howard Taft Road
2nd Floor, Cincinnati, OH 45219
Phone 513.946.7800 Fax 513.946.7890