- There are several species of house dust mites that are found in North America.
These mites are so tiny (about 0.3mm in length) 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.
- The 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
(our perspiration). The food consumption of these mites and development increases at higher relative humidities.
Mites survive best at relative humidities of 70-80% and temperatures of 75-80 degrees F.
House dust mites do not survive well at low relative humidities, especially at higher temperatures.
Temperatures of 140 degrees F for one hour is lethal to these mites.
- Unlike some other kinds of mites, house dust mites are not parasites of living plants,
animals, or humans. House dust mites primarily live on dead skin cells regularly shed
from humans and their animal pets.
- A Primary source of dust mite exposure in the home is in the bedroom, which provides the best
conditions of warmth, humidity, and food for their growth. They are present in mattresses, pillows,
blankets, carpets, upholstered furniture, curtains, and similar fabrics. The average bedroom can be
infested by millions of microscopic dust mites. We spend around one third of our lives
in the bedroom so we are in close and prolonged contact with dust mites.
- House dust mites are found in virtually all homes, no matter how clean. They live in the dust that
accumulates in carpets, fabrics, furniture and bedding.
- A gram of house dust (approximately half of a teaspoon) contains as many as 1,000 dust
mites. That same gram of dust holds 250,000 of their fecal pellets.
- A dust mite will produce 20 fecal pellets per day, that is 200 times its own body weight in feces
during its short lifetime. With millions of dust mites living in one bed this means there are vast
amounts of droppings there. These levels mean that virtually all dust mite sensitive people will
experience problems as a direct result of the dust mites and their droppings in their mattress, pillow and duvet.
- Research shows that during one nights sleep most people toss and turn up to 60 or 70 times meaning the
dust mite droppings are frequently expelled into the air from bedding. Researchers have also
discovered that the allergens can then stay in the air for up to 2 hours. Once airborne, dried dust
mite droppings are easily inhaled into our airways thus causing allergic reactions in asthmatics.
These allergens can cause wheezing, coughs, itchy eyes, sniffles and, in more serious cases,
asthma, eczema, and allergic rhinitis.
- It is not the dust mites themselves that causes the problems, the allergen which causes asthma attacks,
allergies and eczema is actually a protein found in their droppings and their carcasses.
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