Taxonomic placing: Acari, Acariformes, Astigmata.

Common name: Acarids.

Whitish, slow moving mites whose prodorsum is usually covered by a shield-like sclerite. They have a sejugal furrow, carry long, slightly barbed setae on the hysteronotum, and their tarsi bear well-developed empodial claws. The hypopodes possess dissimilar morphological aspects.

Due to their dentate mouthparts acarids can consume particulate foods, such as plant parts, soft-tissued animals and seeds. Acarids abound in leaf litter and in the upper strata of soils rich in organic matter, as well as in dried meat and fruits and in decomposing animal droppings.

A few species ccur on plants or in standing waters and they may contaminate laboratory cultures {e.g. Tyrophagus putrescentiae (Schrank)}, which can also cause dermatitis and allergies]. Acarids are especially abundant in stored foods, of which they can be major pests (e.g. the flour mite, Acarus siro L., which although present in the Middle East, is not considered to be an economic problem). The reproduction of most species is sexual, the sex ratio tending to be F1:M1. When the younger stages of most non-parasitic Acaridae are exposed to adverse conditions (e.g. low relative humidity, extreme temperature, lack of adequate food) they molt to become hypopodes, whose development may continue when suitable conditions return.

Rhizoglyphus robini, a soil-borne species, is one of the few plant pests in this family.


Hughes, A.M. 1976. The Mites of Stored Food and Houses. Her Majesty’s Stationery Office, London.

Krantz, G.W. and Walter. D.E. (eds) 2009. A Manual of Acarology, 3rd Ed. Texas Tech University Press, Lubbock, Texas.

OConnor, B.M. 1982. Astigmata. In: Synopsis and Classification of Living Organisms (Ed. by S.P. Parker), pp. 146-69. McGraw-Hill, N.Y.