If I had to pick the most misunderstood creature I regularly encounter at the UW Insect Diagnostic Lab, it’d be bird mites. Perhaps you’ve never even heard of bird mites before—tiny arachnids that suck the blood of the birds nesting in your back yard. Under the right conditions, those same mites can wander indoors and be a temporary nuisance to humans.
If you haven’t heard of bird mites before, your first inclination may be to do a quick Google search to learn more. Unfortunately, the Internet is rife with misinformation about these creatures. In the age of fake news, here’s another gentle reminder to assess the credibility of online sources. I’ve encountered “official sounding” websites full of misleading, downright wrong, and in some cases, dangerous management recommendations about bird mites. I’ve also had to console clients on multiple occasions because they’ve read about bird mites online—only to believe that the mites will be infesting themselves, their homes, and vehicles indefinitely.
Although small (<1 mm long), bird mites can be seen with the naked eye, and their nearly constant movement helps give them away. Perhaps the best description of their appearance is walking flakes of pepper. Under magnification, bird mites have a somewhat tick-like appearance with their eight legs and long, prominent mouthparts. The mites are often whitish in color with some black on the body but can turn darker after feeding. Each year, I typically bump into 10-20 bird mite cases during the spring and summer months. The mites can actually be quite common but simply aren’t encountered unless you have a bird nest very close at hand: under a back deck, on a patio light fixture, in a gutter or a damaged soffit area or in a shrub just outside a bedroom window.
True to their name, bird mites are parasites that feed on the blood of birds. These mites are often most noticeable when young birds have just left the nest and the mites wander desperately looking for a blood meal. Without their avian host, bird mites have a short time to live, but they can make their way indoors where they can crawl on and inadvertently try biting humans and pets. Although the mites can be an itchy tingly nuisance, bird mites cannot survive on humans or in homes for any significant length of time. The literature suggests that off of their avian hosts, the common bird mites may be able to survive a matter of weeks under the most ideal of conditions. In most cases, the conditions off the birds are so hostile (too dry) that survival is limited to a few days at best—especially in a modern home with air conditioning.
As with many pest control situations, eliminating the source of the problem often brings about rapid results and bird mites aren’t any different. If you’ve found bird mites, removal of the bird nest once the birds have left the nest is the single most important step. Like flipping a switch, mite activity typically drops off rapidly within a day or two of the nest being removed. Indoors, dry conditions pose the biggest threat to bird mites, so running your AC and/or dehumidifier may help hasten their demise. Vacuuming, using sticky tape, or wiping up mites with a damp soapy cloth can all help eliminate any additional stragglers that made it indoors. Pest control professionals typically also apply to residual product to nearby areas to help control any residual mites.
If you think you may be dealing with bird mites, contact the local University Extension service in your state/country for advice.