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Psocids/Book Lice/Dust Lice (Psocoptera)

Size and colour

Lice are the size of a pin head. They are white, pale grey or black with soft bodies.


There are many different types.They can be found in old books as they feed on the starch of the bindings, carpets and other furnishings in the home.

What are psocids?

Psocids are common but harmless household pests that can live in dry powdery type foods. They do not like the light but prefer to live in dark, warm, humid places such as the folds of packaging in food cupboards. They can live for about six months and in that time a female will lay up to 200 eggs.


They feed on microscopic moulds and mildews which flourish in warm, humid places such as a kitchen.

What causes them?

They are associated with high humidity. This might be caused by new plaster drying out, or could be due to condensation from not having enough ventilation in your kitchen. A kitchen is likely to provide conditions they need and fitted cupboards provide darkness which attracts them. With ideal conditions they can rapidly increase in number.


Eliminate damp conditions. Always keep your dry foodstuffs in a cool and dry well ventilated place. Clean your cupboards regularly and make sure they are completely dry before you put food back. Make sure the kitchen is properly ventilated if cooking, boiling the kettle or using the washing machine or tumble dryer. If condensation shows on the windows, it is being produced on all other surfaces as well, leading to mould growth on which psocids thrive.


If the number of psocids does not reduce or continue to present a nuisance after the recommended course of action, email us at or on 01329 236100.

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