There are a number of species of mites that fall under the general name “bird mite.”
Most common among them is the northern fowl mite (Ornithonyssus sylviarum). These mites are parasites of birds and usually found on the birds or in their nests. Under normal conditions, bird mites go unnoticed by us. However, there are occasions when mites are forced away from their preferred hosts and wander into our homes as accidental invaders.
Sometimes this time of year, people will deliberately bring in bird nests to be used ads part of a decoration. Bird mites can bite humans but don’t pose a health threat. They don’t transmit any diseases to us and are, for the most part, merely an annoyance. However, two years ago in North Carolina, last year in Idaho and recently in New York City bird mites made the news by forcing people from their homes.
In the case of the lady in New York, she was removed from her home in a HazMat suit and taken to a local hospital where she spent two days undergoing treatment for the bites. Other than a rash, the woman suffered little in the way of physical impairment. However, the psychological trauma was enough for her to file a lawsuit against her landlord.
The northern fowl mite infests domestic fowl, house sparrows, pigeons, starlings and other wild birds commonly associated with people. Populations of this mite can build up very quickly with a single generation completed in five days. By the time a young bird leaves the nest, they can be infested by thousands of mites. The northern fowl mite spends virtually its entire life on its bird host. Mites that fall off their host can survive only for about a week to 10 days. At this point, when the birds leave the nest, large numbers of mites invade buildings looking for another host.
Finding and eliminating bird roosts and nests is the first step in controlling bird mites. When removing nests, make certain that you wear gloves and a long-sleeved shirt. Place the nest detritus in a plastic garbage bag and dispose of it carefully. There is a caveat regarding the removal of nests. Whereas pigeons, sparrows and starlings nests can be readily removed and destroyed, other bird’s nests, like those belonging to chimney swifts, are protected under the Federal Migratory Bird Treaty of 1918.
The best approach in this situation: install a screened cap to your chimney in the fall of the year when they aren’t nesting. Once you’ve removed the nest, the area around the nesting site should be treated with one of the synthetic pyrethroids such as bifinthrin, cyfluthrin or lamda cyhalothrin. After this is done, you need to try and make the nesting site unattractive to future avian tenants. Fix or block openings in the eaves of your house, in wall cavities and around roof spaces. Don’t forget to take a look at your window ledges and around window air conditioners.
If you suspect your house has already been invaded by these creatures, vacuum the room and use a “bug bomb.” That will probably do the trick or you can wait them out. The mites won’t survive over a week once their bird meal is gone. Just apply a coating of a repellant containing DEET or picaridan so it won’t be appetizing. However, if you have a continuous population of nesting/roosting birds, like pigeons, the problem can become more than a nuisance. At that point, you need to contact a professional pest management specialist.
Tim Lockley, a specialist in entomology, is retired from a 30-year career as a research scientist for the U.S. Department of Agriculture. For answers to individual questions, please send a stamped, self-addressed envelope to Tim Lockley, c/o Sun Herald, P.O. Box 4567, Biloxi MS 39535.