Book Lice (Psocids)

Since 31 August 2013 the Council has ceased to offer a pest control service to residents. This information page is a guidance for residents.

What do they look like?

Psocids are soft-bodied insects, yellowish brown in colour and rarely exceed 1-2mm in length. Some species have 2 pairs of membranous wings although there is the tendency to loss of wings in many species.

How do they live?

Psocids are widely spread throughout the UK with the greatest activity being between April and November. A population of psocids will develop more successfully in warm, damp conditions or places of high humidity i.e. kitchens.

The female may produce up to 200 eggs during her life, laying between 1-3 per day.

The eggs are sticky and pearl in colour and soon become covered in fragments of food and debris. The eggs hatch between 1-2 weeks to produce a nymph which resembles the adult.

Depending on the species, the nymph passes through 3-8 molts before it reaches maturity in approximately 15 days. The lifecycle is usually complete in approximately 1 month and the adult may survive up to six months.

How do they affect me?

  • Psocids are harmless in small numbers and rarely cause damage by direct feeding. However, large number may cause damage to delicate materials such as books and fur.
  • Signs of an infestation are holes and tunnels in which the insect hides plus a covering of white powdery material and salt crystals.
  • They will contaminate raw, processed foods and infest items such as bagged nuts, chocolate, milk powder, cereals, sugar, flour to name just a few.
  • Finished products may become infested in either warehouses, retail premises or the home.

How do I control them?

The most effective method of control is to ensure the premises is thoroughly aired and dry to reduce the risk of moulds developing, thereby denying the insect a food source.

Packet foods should be stored in well ventilated cupboards, away from cookers and sources of steam, with sufficient space to allow a good airflow

Cupboards and storage areas should be regularly cleaned and food debris not allowed to accumulate in cracks and crevices. Ensure good stock rotation, Regularly inspect cupboards and packets for signs of infestation. Infested commodities should be identified and destroyed.

Psocids are susceptible to a wide variety of insecticides however, the problem lies in ensuring the pest comes into contact with the insecticide.

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