House Dust Mites


The adult mite is around 0.3 – 0.5 mm in length. The body is ribbed and slightly pinkish in appearance. There are two pairs of bristles from the posterior end of the body which are shorter than the length of the body.


Females have an egg-laying period of between 15 and 20 days, each female lays around 30 eggs. After 10 days or so the eggs hatch and the larval stage emerges. After approximately 10 days, the larva transforms into the protonymph which subsequently, after another 10 days, forms the tritonymph. The adult emerges from the tritonymph after 10 days. Development times are greatly dependent upon atmospheric temperature and humidity and may vary from this norm. The mites feed on skin scales which are constantly shed from the human body and accumulate in beds and furniture. They may also feed on dry material such as fish meal and other stored foodstuffs. The life cycle may be completed in three weeks in favourable conditions.




Mites of this genus have been implicated in causing dermatitis, rhinitis, respiratory tract irritation and intestinal upsets. They are also implicated in the cause and spread of asthma and other respiratory complaints. The evidence for the link is growing and there seems to be a certain proportion of the population who react to these mites. The mites are more abundant in beds than anywhere else in the house, and easily become airborne. Consequently they are easily inhaled. Allergens are contained not only in the bodies of the mites but also in fragments and faeces.


Physical House Dust Mites control measures including drying of the environment and vacuum cleaning are excellent initial measures. Acaricides may be used on the fabric of the building, skirting boards, floorboards, etc. If soft furnishings are to be treated then care should be taken to select a non-staining formulation. The use of a dehumidifier may prove successful

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