House Dust Mites

The Biology of Dust Mites 

There are two species of house dust mites, belonging to the genus Dermatophagoides, which are found in North America. These mites are so tiny that they are virtually invisible without magnification. They pass through six developmental stages, and the adult form may also molt once. Adult female mites lay cream-colored elliptical eggs coated with a sticky fluid that helps them adhere to the substrate. Under optimal conditions, the cycle from egg to adult mite takes about one month. 

Both species of house dust mites feed on human skin scales, pollen, fungi, bacteria, lepidopteran (moth and butterfly) scales, animal dander, and skin scales of birds. Human, cat, dog, and horse dander have been used to raise these species in a laboratory. Dust mites do not drink free water, but they absorb water from the air and the environment. The food consumption of these mites and development increases at higher relative humidity. Mites survive best at a relative humidity of 70-80% and temperatures of 75-80 degrees F. House dust mites do not survive well at low relative humidity, especially at higher temperatures. A temperature of 140 degrees F for one hour is lethal to these mites.   

Organisms Found in House Dust

This drawing shows the important allergen-producing organisms and relative amounts of their body parts and by-products found in one gram of house dust.

Typical Constituents of House Dust: ash, cigarette; combustion products; fiber, synthetic textile; fibers: wool, cotton, paper and silk; fingernail filings; food crumbs; glass particles; glue; graphite; hair, human and animal; insect fragments; oil soot; paint chips; plant parts; pollen; polymer foam particles; salt and sugar crystals; skin scales, humans; skin scales, pets; soil; spores, fungal; stone particles; wood shavings.

Dust Management. Getting rid of allergy-inducing dust mites and other allergy-inducing constituent of dust is related to eliminating dust from the environment. The most important tool for managing house dust mites is the vacuum cleaner. Regular, thorough vacuuming of carpets, furniture, textiles and other home furnishings such as draperies will help keep dust mite populations low.  Avoid wet mopping because it increases moisture in the air.  Where wet mopping is necessary, as in kitchens and bathrooms, vacuum thoroughly first. Vacuums with a water filter are preferable to those with a disposable paper bag because a water vacuum removes a greater range of particle sizes than paper-bag types. There are a number of vacuums with highly efficient filters designed for use by people with allergies to dust. It is better to vacuum thoroughly once a week rather than lightly on a daily basis. Vacuum mattresses and padded furniture thoroughly, 20 minutes for each mattress is not too long. Dust furniture before you vacuum so the dust has time to settle on the floor, where it can be picked up by the vacuum. Special dust cloths or other cleaning implements that are treated chemically to hold rather than scatter dust may be helpful. You may also wish to use an electrostatic precipitator to help reduce small particles in the air.

Control Other Insect Pests. Other insect pests in the home may contribute to allergies and mite populations so suppressing populations of fleas, cockroaches, and silverfish will minimize additional allergens in the home. Store grains and crackers in glass containers with good rubber seals that close by pressure. You may wish to store these containers in the freezer. 

Low Humidity. The humidity in the house should be kept below 70%. During humid times of the year, it might be useful to run dehumidifiers in bedrooms and/or particularly damp areas of the home. In addition, bathroom and laundry rooms can be vented to remove humid air to the outside with a fan. 

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