Flour Mite / Grain Mite

Scientific Name: Acarus siro

Order & Family: Order: Sarcoptiformes, Family: Acaridae

Size: Microscopic to barely visible, roughly 0.3 mm to 0.6 mm in length

Flour Mite / Grain Mite

Natural Habitat

Found in stored food products, typically in high-humidity environments. Commonly infests flour, grains, cereals, cheese, and dried fruits.

Diet & Feeding

They feed on fungi and mold found on stored food products, as well as the food product itself (e.g., the germ of grains).

Behavior Patterns

They reproduce rapidly in humid conditions. When populations explode, they appear as a moving 'dust' layer on food. They are known for their ability to enter a 'hypopus' stage where they become resistant to desiccation and can hitch rides on other insects.

Risks & Benefits

Risks: Can spoil large quantities of stored food, causing a distinct 'minty' odor and bitter taste. Their waste and dead bodies are common allergens, known to cause 'baker's lung' or 'grocer's itch' (dermatitis) in sensitive individuals. Benefits: None significant in a domestic context; they are primarily pests.

Identified on: 2/16/2026