Grain Mites

or flour mites (Tyroglyphoidea or Aca-roidea), superfamily of arthropods from the order Acari-formes and the class Arachnida.

Grain mites are small—0.2–1 mm; there are about 200 species spread throughout the world. The mites dwell in the soil, in accumulations of rotting matter, in burrows and nests of animals, and on the roots and green parts of plants, feeding on plant matter and microflora. They multiply intensively in humid areas.

Grain mites are characterized by a special development phase, the hypopus, into which the nymph turns under such unfavorable conditions as insufficient moisture or food. Covered by a carapace, the hypopus is very resistant to external effects; it does not feed but migrates by attaching itself to insects and other animals. When favorable conditions are restored, the hypopus molts and begins a new colony of grain mites.

Grain mites are carried into storage areas from the fields during harvesting. Grain and cereal products are damaged by the long mite (Tyrophagus noxius, Tyrophagus per-niciosus), the flour mite (Tyroglyphus farinae), the dark-legged mite (Aleuroglyphus ovatus), and others. Onions are damaged by the bulb mite (Rhizoglyphus echinopus); cheese by the cheese mite (Tyrolichus casei); and wine by the wine mite (Histiogaster bacchus), which dwells on the surface of wine.

Grain mites, when ingested with food, irritate the walls of the gastrointestinal tract and, when inhaled, cause asthmalike symptoms.

Protection of foodstuffs against grain mites is based on the creation of unfavorable conditions for them such as low humidity and temperature and fresh-air ventilation. Chemical compounds—acaricides—are also used to eliminate grain mites from planting grain.