Once spring rolls in, so do the ringing phones with a familiar complaint. “Help! I’m being bitten by spiders while I’m sleeping!”
PMPs know that it is highly unlikely that a spider is biting someone while they’re in bed. But for this potential customer, the bites and itching are a very real problem. And the cause might be from the bird nest in the eaves just outside their home.
Every year, beginning around mid-May, peaking in the summer and continuing through early September, Pinpoint Pest Control in Southern California receives a number of phone calls from individuals who report being bitten by tiny creatures. These potential clients suspect pests such as spiders, mosquitoes, fleas or bed bugs. However, after interviewing the customers, Pinpoint has found that there are some key indicators, including reports of bites and bird nests, that lead them to suspect bird mites.
Bird mites are only about 0.6-1.5 millimeters long, much smaller than bed bugs. They are blood feeding ectoparasites of both domestic fowl and wild birds, including pigeons, starlings and sparrows. In the right conditions, such as warming temperatures and the presence of a host, some bird mite species can go from egg to adult in under a week. Thus, populations can increase quickly. In a short time, a small bird nest can be infested with hundreds of mites.
Troublesome infestations begin in bird nests, often along window ledges, under eaves, in air-intake ducts and similar areas where birds commonly nest around structures. The most common reason for indoor infestations occurs when nests are abandoned due to baby birds leaving or the death of the residing bird. Without a host for a blood meal, the mites search for other sources from which to feed and survive. Mites can also become a problem for nearby humans when the mite population in the nesting area grows too large and some mites venture off.
Picture of bird mite. Josh Shoemaker
Bird mites are unable to fly. Nests in trees or locations not adjacent to a dwelling usually do not cause bird mite issues inside. But if an infested nest is contiguous with a house, the mites may find a pathway inside through cracks or other small openings.
The host-seeking behavior of bird mites is not fully understood, but it is thought that heat, vibration and carbon dioxide are important stimuli.1,2 It is not uncommon to find bird mites on electronic items that are emitting heat, such as mobile phones, computers and LED clock displays.
For Pinpoint customers, a frequent complaint is that the mites drop down from the ceiling on to individuals or their belongings. In one particular case we visited, the teenage children were complaining that they kept having mites drop on their smart phones and other electronic device screens. To our knowledge, this behavior hasn’t been documented in the literature, but it is very common to hear this from those with infestations. Pinpoint technicians who have inspected and found bird mites in homes also report that when mites are observed on walls, they are nearly always traveling upward.
To further examine this behavior, an abandoned bird’s nest that was infested with a massive number of mites was placed in a large, sealed plastic bag for observation. Over the course of several days (including multiple times per day), the bag was rotated, and each time, the mites would immediately begin heading up to the highest part of the bag. In a short time, nearly all the mites would be along the top edge. This could help explain the frequent reports of mites dropping on individuals. It seems the mites travel up walls and across ceilings, where they drop on sleeping victims below.
Once bird mites find a host, they use their mouthparts to pierce the skin to reach dermal capillaries. They inject substances that in humans can cause inflammation and small, itchy red bumps.3 They typically feed for only a few minutes. Like bed bugs, bird mites generally feed on the host during the night and retreat to harborage areas during the day. Feeding generally occurs every two to four days, but this can vary based on conditions. Some species require a blood meal within about 10 days to survive, but others have demonstrated the ability to survive months without feeding.2,4 Mites kept in the bag noted above survived over two months.
Their preferred hosts are birds, and it has been suggested that the surface of the skin is the main inhibiting factor in humans. Still, some infestations where bird mites are known to be feeding on human hosts have been documented to persist.2 Pinpoint has also found that people often report that only some individuals in the residence are being bitten, while others are not (though this may be analogous to how individuals react differently to bed bug bites).
Once bird mites have been identified, and the source(s) found, the infestation is generally simple to eliminate. The most important step is that any and all bird nests must be removed. In a specific instance, two nests were removed from around a home. Ongoing reports of bites from a child in the home led to a more detailed follow up inspection where a nest was discovered inside a soffit area that was not visible. Once this nest was located and removed, the bites stopped.
As noted, bird mite infestations indoors are most often the result of abandoned nests. Yet, even without a host bird present, some mites can live in these nests in the right conditions for several months and continue to infest the structure. Therefore, finding and removing abandoned nests and treating the old nest area is critical.
In Pinpoint’s experience, rarely does a bird mite infestation occur while the nest is occupied, but it can happen. Be aware, however, that in many states there are laws regarding the removal or relocation of an active bird’s nest. Generally, it is illegal to remove an active bird nest (except for invasive species). Be sure to check with your local authorities.
Again, simply by removing the bird nest(s), the problem will eventually go away, but this can take several weeks or even months for all the mites to die. Most people will want mites that have become a problem indoors to be eliminated in short order.
Pinpoint treats in the house using the following protocols. First, an aerosol application of pyrethrin is directed toward the walls and vertical surfaces inside the home to either kill exposed mites or flush them out of cracks and crevices. This is followed by a residual application around the edges of floors and in key spots of the home with a pyrethroid or pyrethroid combination material. A total release fogger is also often used to kill as many bird mites as possible in the attic and/or sub area.
Pinpoint completes each bird mite job by offering to install bird deterrents. It is common for birds to return to where they were hatched, so many customers will opt for this added service to have the peace of mind of knowing that this itchy problem won’t return.
Based on Pinpoint’s experience, customers sometimes report bites for up to two weeks following a successful treatment. Whether this is residual mite activity or delayed reactions to bites is unknown. Still, it’s best to warn clients of this prior to starting service.
So, if a report comes in for spiders or bed bugs, and none are found, it’s probably a good idea to take a look around the structure for nests, as bird mites might be the problem.
Josh Shoemaker is an urban entomologist focused on pests of public health importance. Steve Tanksley is an Associate Certified Entomologist and owner of Pinpoint Pest Control.
1 Murillo, A.C. & Mullens B.A. (2017). A review of the biology, ecology, and control of the northern fowl mite, Ornithonyssus sylviarum (Acari: Macronyssidae). Veterinary Parasitology, 246, 30-37.
2 George, D.R., Finn, R.D., Graham, K.M., Mul, M.F., Maurer, V., Moro, C.V., & Sparagano, O.A.E. (2015). Should the poultry red mite Dermanyssus gallinae be of wider concern for veterinary and medical science? Parasites & Vectors, 8(1).
3 Kramer, L., Weinberger, M., Tanksley, S., & Shoemaker, J. (2022). Pruritic papular dermatitis from bird mites. The journal of allergy and clinical immunology. In practice, 10(6), 1642–1643.
4 Gold, R.E. & Jones, S.C. (2000). Handbook of Household and Structural Insect Pests. Entomological Society of America. Lanham, Md.
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