Understanding the Threat of Biting Mites in Your Environment

Northern Foul Mite

These mites can cause epidemics of dermatitis during harvesting and post-harvesting operations in straw, hay or certain grains. Bites produce a rash-like dermatitis, extending over much of the body and accompanied by itching, sweating, fever, headache and even vomiting in severe cases. They are beneficial because they feed on larvae of wheat jointworm, rice and granary weevils, Angoumois grain moths and other pests.

This barely visible mite completes development on the host bird (i.e., poultry, pigeons and starlings) and will leave the body of a dead host in large numbers to wander over walls, ceilings and bedding, seeking a new host. Bites can cause itching and dermatitis. This mite can survive two to three weeks away from the host.

"Bird mites" or "Tropical fowl mites" are the common names used to describe the mite Ornithonyssus bursa from the family of mites Macronyssidae; these mites are often incorrectly called ‘bird lice’, particularly within the pest control industry, and are also commonly the cause of ‘paper mite’ problems (strictly speaking there are no such things as ‘paper mites’). This species of bird mite is widely distributed throughout warmer regions of the world.

The mites are haematophagous (feed on blood) natural parasites of common birds including pigeons, starlings, sparrows, Indian mynahs, poultry, and some wild birds. Ornithonyssus bursa mites are small with eight legs, barely visible to the eye, oval in shape with a sparse covering of short hairs, and are extremely mobile. They are semi-transparent in colour which makes them difficult to detect on skin until blood is ingested and then digested - when they may appear reddish to blackish.

Contact with humans occurs after the birds gain entry through unprotected eaves, or to roof cavities via broken tiles to construct their nests in homes, factories, barns and other dwellings in early spring or summer. The large amounts of nesting material used by the birds provide the mites with an ideal environment in which to thrive. The unfeathered nestlings plus the adult birds occupying the nest are utilised as a ready blood source for the expanding population of mites. When the young birds are ready to fledge, some mites remain attached to the feathers of their bird hosts and feed intermittently. The mites remaining in the abandoned nest, and left without a suitable host when the birds leave or die, will roam and disperse throughout the dwelling over a 1-2 week period searching for new hosts. Most mites will die within 10 days without a blood meal from a bird host. They will bite but cannot survive on humans and do not infect/infest human skin.

Chicken Mite

This mite feeds on the host at night and hides in cracks and crevices during the day. It feeds on poultry, sparrows, canaries and other birds. A new generation may occur every 7 to 10 days. Bites cause itching and light dermatitis. These mites enter a house after death of the host bird or departure from the nest. They can live for a month or more without a blood meal.

Tropical Rat Mite

This mite will feed on humans even when rats are present, causing painful bites, intense itching and dermatitis. Barely visible, they are bright red to black with white markings and are usually noticed on walls in basements, kitchens, bathrooms and where rats are found. Mites drop from their host after each blood meal and can survive several days without feeding.

House Mouse Mite

This mite is found on mice and can bite humans. It will wander away from mice onto walls.

Follicle Mite

The follicle mite is more worm-like. These microscopic mites live in the hair follicles or sebaceous glands of most humans. Very few persons are allergic to them. Those who are may lose their eyelashes or develop acne.

Itch or Scabies Mite

This mite is similar to those that attack livestock, horses, dogs and rabbits. Transmission is usually by direct contact with an infested person. Itch mites tunnel into the skin, especially on hands and wrists. Nodules burst and ooze serum, later hardening to form scabs. The skin between the fingers is often invaded. Itching is intense and known as "scabies" or "seven-year itch." Scratching can cause bleeding and infection of open sores. Overlapping generations occur at two to three week intervals.

Grain and Mold Mites

These mites can be found in a wide variety of stored products and food and can cause mild dermatitis known as "grocer's itch." Heavy infestations have a sweet or minty odor. A coating of "mite dust," molted skins of the mites, covers the infested grain or cheese. Sometimes the surface of infested materials appears to move due to large numbers of mites. These mites favor damp areas. They do not bite humans.

House Dust Mite

These mites are found in mattresses, pillows and furniture containing natural fibers. They are scavengers that feed on human skin scales and other detritus but do not bite humans. About 90% of the persons allergic to house dust extracts are allergic to house dust mite extracts. Only about 10% of those not allergic to house dust extract are allergic to the dust mite extract. Over half of all homes are believed to be infested with the house dust mite.