Pyroglyphidae is a family of non-parasitic

mite Mites are small arachnids (eight-legged arthropods) of two large orders, the Acariformes and the Parasitiformes, which were historically grouped together in the subclass Acari. However, most recent genetic analyses do not recover the two as eac ...

s. It includes the

house dust mite House dust mites (HDM, or simply dust mites) are various species of acariform mites belonging to the family Pyroglyphidae that are found in association with dust in dwellings. They are known for causing allergies. Biology Species The curren ...

s that live in human dwellings, many species that live in the burrows and nests of other animals, and some pests of dried products stored in humid conditions.

Etymology

The naming of the family originates from the fact that dust mites cause

eczema Dermatitis is a term used for different types of skin inflammation, typically characterized by itchiness, redness and a rash. In cases of short duration, there may be small blisters, while in long-term cases the skin may become thickened ...

, with intense itching and a red rash. The condition has been described as like burns from fire on the skin, with a 'burning' itching sensation, hence the word 'Pyro' in 'pyroglyphidae'.

Characteristics

Mites in this family are very tiny; the female American house dust mite ('' Dermatophagoides farinae''), for example, measures about 420 microns in length and 320 microns in width, with the male being somewhat narrower.

Ecology

These mites mostly live in the nests and burrows of animals and birds where they feed on

detritus In biology, detritus ( or ) is organic matter made up of the decomposition, decomposing remains of organisms and plants, and also of feces. Detritus usually hosts communities of microorganisms that colonize and decomposition, decompose (Reminera ...

from the skin and feathers of their hosts. They need a humid atmosphere because the air is their only source of moisture. They thrive when the

relative humidity Humidity is the concentration of water vapor present in the air. Water vapor, the gaseous state of water, is generally invisible to the human eye. Humidity indicates the likelihood for precipitation (meteorology), precipitation, dew, or fog t ...

is greater than 50% but become desiccated and die at lower relative humidity levels. Other mites in this family feed on stored products such as grain, cereals, nuts, dried fruit, cheeses and pet foods, but only in conditions of high relative humidity. The sexes are separate in this family. The female lays two or three eggs each day and these develop through several stages;

larva A larva (; : larvae ) is a distinct juvenile form many animals undergo before metamorphosis into their next life stage. Animals with indirect development such as insects, some arachnids, amphibians, or cnidarians typically have a larval phase ...

, protonymph, trytonymph and adult. At , the complete cycle takes 34 days, but the length of time taken varies with the temperature and relative humidity. If the latter is very low, the protonymph can enter

diapause In animal dormancy, diapause is the delay in development in response to regular and recurring periods of adverse environmental conditions.Tauber, M.J., Tauber, C.A., Masaki, S. (1986) ''Seasonal Adaptations of Insects''. Oxford University Press It ...

, surviving for several months in a quiescent state until conditions improve, after which development recommences.

House dust mites

Three species of house dust mite are commonly found in human dwellings; '' Dermatophagoides farinae'', '' Dermatophagoides pteronyssinus'' and '' Euroglyphus maynei''. They feed on flakes of skin found in dust and typically occur on carpets, around sofas and chairs, and on mattresses. They may be very plentiful in the humid tropics, but in temperate climates are more numerous in humid summers than in winters, when the relative humidity is usually lower in homes. Some people suffer a reaction to

allergen An allergen is an otherwise harmless substance that triggers an allergic reaction in sensitive individuals by stimulating an immune response. In technical terms, an allergen is an antigen that is capable of stimulating a type-I hypersensitivi ...

s present in the faeces of

s. These may cause

atopic dermatitis Atopic dermatitis (AD), also known as atopic eczema, is a long-term type of inflammation of the skin. Atopic dermatitis is also often called simply eczema but the same term is also used to refer to dermatitis, the larger group of skin conditi ...

or be inhaled giving rise to

asthma Asthma is a common long-term inflammatory disease of the airways of the lungs. It is characterized by variable and recurring symptoms, reversible airflow obstruction, and easily triggered bronchospasms. Symptoms include episodes of wh ...

rhinitis Rhinitis, also known as coryza, is irritation and inflammation of the mucous membrane inside the nose. Common symptoms are a stuffy nose, runny nose, sneezing, and post-nasal drip. The inflammation is caused by viruses, bacteria, irritant ...

References

External links

* * {{Authority control Acariformes Acari families