Flour mite

(Acarus siro)


Flour mites are very small creatures, measuring just 0.3 to 0.5 mm, which have 6 legs as larvae and 8 as adults. They are part of the arachnid class. The flour mite is shaped like an elongated oval and is whitish in colour. On its body, it has just a few somewhat short bristles; however, on its rear, it has two pairs of rather long tail hairs. Flour mites usually start as eggs, then go on to become larvae before going through various nymph stages and then finally becoming adults. However, special survival forms can also develop, which can withstand unfavourable conditions for a very long time. If the living conditions are ideal, this usually leads to mass reproduction.

The creatures can develop at temperatures of between 10 and 35 °C. At temperatures below 5 °C, their development stops, but they can hibernate in unheated rooms to a limited extent.

A sufficiently high level of substrate moisture seems to be more important for their development – this needs to be above 14 %.



Flour mites primarily infest grains, pasta and baked goods and, more rarely, animal products, such as dairy products. Affected products are covered with a light layer of dust, go off and often taste bitter.

Food contaminated with flour mites smells sweet, is no longer suitable for consumption and can cause severe allergies, asthma attacks and other symptoms.