Flour mill beetle

Classification

Primary pest; grain feeder
Order: Coleoptera
Family: Laemophloeidae
Acronym: CTU

Description

• Flour mill beetle is often confused with the flat grain beetle (Cryptolestes pusillus).
• Adults are small (1.5 to 2.0 mm), reddish brown and flattened with long bead-like antennae.
• Adults have a ridge (sublateral carina) on the head and prothorax.
• Larvae are elongate and flattened with well developed legs.
• Larvae are pale, white to yellow in colour with a darkened head capsule and dark urogomphi present.
• Larvae move actively amongst the food feeding on the endosperm or germ.
• Male antennae are longer (almost as long as body) than female antennae (half the length of the body); rusty grain beetle antennae are the same length in both sexes.

Similar species

• Rusty grain beetle (Cryptolestes ferrugineus)
• Flat grain beetle (Cryptolestes turcicus)
• Foreign grain bettle (Ahasverus advena)

Commodities affected

• Flour, damaged grain
• Waste grain, cacao, spices, dried fruit, copra

Signs of infestation

• Damage is not readily identifiable as being caused by this species.

Damage

• Damage is usually restricted to grain stored under high moisture conditions.
• Both larvae and adults feed on germ and endosperm.
• Heavy infestations may cause grain to heat and spoil.
• Flour mill beetle may spread fungal spores through grain.

How to control

• Control grain insect pests

Geographic range

• Is found in Europe, North Africa, Japan, some South American countries and North America
• Is found across Canada

Where found

• Can survive Canadian winters only in heated structures
• Is found mainly in machinery of flour and feed mills, occasionally in grain elevators and warehouses
• Requires high temperature and relative humidity for optimal development but is cold tolerant

Life history

• Beetle’s development is favored by the presence of fungi in its diet.
• Females lay eggs in crevices or loosely amongst the food.
• Adults cannot climb up glass.