Psocids

Classification

Secondary pest; Scavengers
Acronym: PSO

Various species including:

• Liposcelis bostrychophilus (Psocoptera: Liposcelididae)
• Trogium pulsatorium; (Psocoptera: Trogidae)
• Also Families: Lachesiilidae, Psyllipsocidae

Description

• Are quite small, 1 mm or less in length.
• Larger pale booklouse can reach lengths of 2 mm, similar to some stored-product beetles.
• Have very long, thread-like antennae and have an enlarged hind femur.
• Are soft bodied and often translucent, varying in colour from black to white.

Similar species

• May be confused with some larger species of predatory mites

Commodities affected

• Animal and plant products, fungi
• Stored grain, packaged food, glues, paper products, fabrics

Signs of infestation

• Infestations develop in grain with moisture content higher than 14%.
• Booklice are often associated with presence of moulds.

Damage

• Is a minor pest of stored grain and does not damage sound grain
• Damage is indistinct
• Feeds preferentially on germ of broken kernels and on exposed endosperm of damaged kernels
• Populations may be significant enough to cover walkways in elevators, creating a slipping hazard
• May cause inhalation allergies and respiratory issues in susceptible individuals

How to control

• Control grain insect pests

Geographic range

• Are found around the world and across Canada

Where found

• Prefer moist, humid environments
• Found in granaries, elevators, households, warehouses, processing facilities, museums
• Are associated with high moisture content in stored grain and are found feeding at the tops of the grain bulk

Life history

• Life cycle is incomplete metamorphosis with nymphs morphologically similar to adults.
• Adults may be winged or wingless; nymphs are always wingless.
• Adults prefer breeding conditions with high temperature and high humidity.
• Generally, booklice require humidity higher than 60%.
• Females lay eggs randomly in the food source.