Pest Information – Mites

Mites are among the most diverse and successful of all the invertebrate groups, and because of their small size (most are microscopic) most go totally unnoticed. This site will focus on the mites most commonly found in Hawaii. Learn about their Appearance, Habitat, Diet, Health Risks, and Reproduction.

Bulletin from Hawaii Dept of Health Vector Control Branch

Bird Mites

Scientific Name

Ornithonyssus bursa

Appearance

The Bird Mite is a small yet extremely mobile mite, barely visible to the eye, with eight legs (except the larva which has 6), oval in shape, and with a sparse covering of short hairs. It is typically no more than about .4 mm in length. It has a sharp, protruding mouthpart which allows it to penetrate skin in order to obtain blood from a host. The adult females need blood in order to reproduce. Females typically make up about 95% of the mite population. Bird mites are semi-transparent in color, which makes them difficult to detect on skin until blood is ingested and then digested; then they may appear reddish to blackish.

Habitat

The mite is widely distributed throughout warmer regions of the world. Contact with humans usually occurs after birds gain entry to roof cavities via broken tiles or through unprotected eaves of houses, factories, barns, and other dwellings to construct their nests in early spring or summer. However, some infestations also occur from birds roosting on the outside of dwellings such as window ledges or awnings. The mites feed on the unfeathered nestlings, as well as the adult birds, and the large amount of nesting material used by the birds provide the mites with an ideal environment in which to thrive. The mites have a short life cycle (approximately 7 days) and can rapidly generate large populations.

When the young birds leave the nest or die, many mites (often many tens of thousands) are left behind in the absence of a suitable host, and these will disperse from the nest into and throughout the dwelling searching for new hosts. Although studies have shown that some Bird Mites can survive up to 9 months without ahost, most mites will die within 3 weeks without a blood meal from a bird host. They will bite humans they encounter but cannot survive on humans.

Diet

Bird Mites are parasites, feeding on the blood of common birds including pigeons, starlings, sparrows, Indian mynahs, poultry, and some wild birds.

Health Risks

As a result of their ‘test biting’ on humans while searching for a new bird host, the mites inject saliva. This can lead to severe irritation with rashes and intense itching. Scratching of the bites may result in secondary infections. Bird mites are not associated with the transmission of any infectious disease. The bites are often difficult to diagnose and can be mistaken for bites from a number of other arthropods.

Life Cycle

Their life cycle has four basic stages: egg, larva, nymph and adult. They can complete this cycle in 7 to 35 days depending on environmental conditions. The egg hatches into a larval stage which molts to the nymphal stage. After 1-2 more times, the nymph matures to an adult. Mites, like ticks, have three pairs of legs as larvae and four pairs of legs as nymphs and adults.

Interesting Facts

Mites have successfully colonized nearly every known terrestrial, marine, and fresh water habitat including polar and alpine extremes, tropical lowlands and desert barrens, surface and mineral soils to depths of 10 meters, cold and thermal surface springs and subterranean waters with temperatures as high as 50°C, all types of streams, ponds and lakes, and sea waters of continental shelves and deep sea trenches to depths of 5000 meters. Some idea of mite abundance and diversity can be gained from analysis of one square yard of mixed temperate hardwood or boreal coniferous litter, which may harbor upwards from one million mites representing 200 species in at least 50 families. Within this complex matrix of decomposing plant matter, mites help to regulate microbial processes directly by feeding on detritus and microbes, and indirectly by predation on other microfauna.