​Common Biting Mites

Mites are small pests barely visible to the naked eye. In California, the most common biting mites include the Tropical Rat mite, Northern Fowl mite, and Chicken mite. They feed on rodents, birds, and fowl and occasionally infest homes and bite people.

TROPICAL RAT MITE (Ornithonyssus bacoti)

The Tropical Rat mite feeds on rats and occasionally bites people living in rodent infested buildings. This mite is most frequently encountered in homes when the rat on which it lived has died or left the premises. Its bite may cause a painful skin irritation (dermatitis) which can continue for 2 or 3 days, leaving red spots on the skin. Scratching may result in secondary infections. Not all family members may be affected by the mite.

NORTHERN FOWL MITE (Ornithonyssus sylviarum)

The Northern Fowl mite lives on domestic fowl and many wild birds. It is associated with chickens, pigeons and sparrows. It can become a pest when birds nest under eaves of a house or in the attic. When the birds leave the nest or die, the mites seek a new host.

CHICKEN MITE (Dermanyssus gallinae)

This mite is a parasite of chickens and many other domestic and wild birds. These mites can migrate from the nests of their hosts and invade home. Sparrows, starlings and pigeons are most often the wild birds responsible for household infestations.


Unlike fleas, which tend to bite on the ankles and lower legs, mites may bite anywhere on the body. Bites may occur where clothes constrict the body such as the waistline and under the arms. Mites are usually most active at night. When searching for mites, a flashlight should be used to examine walls near heat sources such as hot water pipes, heating ducts, electrical fixtures, and around bedding (especially heated waterbeds). Mites usually retreat to dark spaces such as cracks and crevices between feedings.


Control of mites is achieved by eliminating the hosts (rodents or fowl), it’s nest, AND chemically controlling existing mite populations. Eliminating the hosts without controlling the mites will only increase mite activity. Mites can live up to 6 weeks without a blood meal.

1. Trap rodents in snap-type traps. DO NOT POISON!

2. “Rodent-proof” home to eliminate rodent entry sites. Refer to Vector Control’s brochure “How to Prevent and Control Rats”.

To view a pdf copy of "How to Prevent and Control Rats" click here.​

3. Remove bird nests under eaves of house.

4. Chemical control of nest-inhabiting mites is best left to a licensed Pest Control Operator.


The Santa Clara County Vector Control District offers free laboratory examinations of mites. Free brochures on rodent and bird control are also available from the Vector Control District.​

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