Who are they

Description:

Coloured scanning electron micrograph (SEM) of a dust mite (Dermatophagoides sp.). 

The house dust mite (sometimes referred to by allergists as HDM) is a cosmopolitan guest in human habitation. Dust mites feed on organic detritus such as flakes of shed human skin and flourish in the stable environment of dwellings. House dust mites are a common cause of asthma and allergic symptoms worldwide. The mite's gut contains potent digestive enzymes (notably proteases) that persist in their feces and are major inducers of allergic reactions such as wheezing. The mite's exoskeleton can also contribute to allergic reactions.

Description

The body of a house dust mite is just visible against a dark background in normal light. A typical house dust mite measures 0.25–0.3 millimetre (0.010–0.012 in) in length. For accurate identification, one needs at least 10× magnification. The body of the house dust mite has a striated cuticle. Like all acari, house dust mites have eight legs (except the first instar, which has six).

Life cycle

The average life cycle for a male house dust mite is 10 to 19 days. A mated female house dust mite can last up to 70 days, laying 60 to 100 eggs in the last 5 weeks of her life. In a 10-week life span, a house dust mite will produce approximately 2,000 fecal particles and an even larger number of partially digested enzyme-covered dust particles.

Habitat and food

The house dust mite survives in all climates, even at high altitude. House dust mites thrive in the indoor environment provided by homes, specifically in bedrooms and kitchens. Dust mites survive well in mattresses, carpets, furniture and bedding, with figures around 100–500 animals/g dust.Even in dry climates, house dust mites survive and reproduce easily in bedding (especially in pillows), which takes up moisture from body contact.
House dust mites consume minute particles of organic matter. Like all acari, house dust mites have a simple gut; they have no stomach but rather diverticulae, which are sacs or pouches that divert out of hollow organs. Like many decomposer animals, they select food that has been already partially decomposed by fungi.

Eradication

House dust mites reproduce quickly enough that their effect on human health can be significant. Since dust mites depend on moisture to survive, they are most often found in bedding such as pillows and duvets. Dust mites numbers can be reduced by replacing carpets with flat surfaces that are easier to vacuum and maintaining relative humidity below 50%. Existing mites can be eradicated through ten minutes' exposure to the lethal temperatures – near 105 °C (221 °F) – in a household clothes dryer, or using disodium octaborate tetrahydrate (DOT) powder. A side-effect of DOT is irritation of eyes.