Flour mite

The flour mite (Acarus siro) is a significant pest of stored agricultural products, belonging to the order Acariformes and the family Acaridae. This microscopic pest is widely distributed globally and represents a major threat to stored grains, flour, oilseeds, cereals, dried fruits, and various animal feed products in storage facilities.

The biology of the flour mite is defined by its ability to thrive in high-humidity environments. Under optimal conditions, including temperatures around 20–25°C and moisture content of the substrate exceeding 14%, the lifecycle is completed in approximately two to three weeks. In adverse conditions, it can enter a resistant stage known as the hypopus, which enables the species to survive extreme conditions and persist in storage infrastructures.

The damage caused by these mites is multifaceted. They feed on the nutritious components of the grain, particularly the germ, which drastically reduces germination rates in seed stocks. Moreover, the mites contaminate the bulk with excrement, cast skins, and dead bodies, imparting a distinct, unpleasant, sweet, and musty odor to the product, making it unfit for processing or consumption.

An infestation is often characterized by the heating of grain mass, commonly known as self-heating. As mites multiply, they increase both the moisture and the temperature of the grain, which creates an ideal environment for secondary colonization by mold fungi. This synergistic effect leads to rapid deterioration, caking, and potential total loss of the stored commodities.

Effective control measures focus primarily on preventative sanitation and environmental management. Maintaining low grain moisture (below 13%) and low temperatures is the most effective deterrent. Regular cleaning of grain silos, proper aeration of the grain mass, and professional fumigation of empty storage facilities are essential strategies to mitigate the risk of flour mite outbreaks and ensure the longevity of the stored goods.