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Booklice belong to a group of insects known as "psocids", and are a common but harmless insect that can usually be found in animal nests, tree trunk crevices, under bark or on leaves. They are known better, however, as pests in the home, food manufacturing premises or retail premises.

What are psocids?

Psocids are tiny grey or brown insects. They are usually between 1mm - 1.5mm in length, and can only walk, not jump or fly. They can live for up to 6 months, during which time the females may lay up to 100 eggs. The eggs hatch after 11 days into nymphs which become adults after about 15 days.  Due to their short life cycle, relatively long adult life and large number of eggs, they can reproduce rapidly, and infestations can occur very quickly.

What attracts them?

Despite their common name - which they get from their habit of lurking amongst old books and feeding on the paste used to bind the pages - this is not the only place they can be found. They may frequent wall paper and recently laid plaster, as they get attracted to the bacteria and moulds which grow in damp conditions.

They are also attracted by the warmth and damp often found in kitchens, especially the darkness of kitchen cupboards. Some foods, including flour, milk, powder, sugar and semolina, naturally contain moisture and it is here that psocids are likely to increase rapidly in number. However, the food itself is not always at fault. Due to the psocids very wide spread distribution, it is usually impossible to find out whether booklice were present in the foodstuffs from the factory or shop, from entering the packaging in the larder or cupboards, or whether they came from another source such as transport, pallets, or packaging materials.

Bathrooms as well provide ideal conditions. Moisture in these and other rooms in the home can be caused by not enough ventilation - this is most likely to happen during the summer months.

Do psocids cause any harm?

Psocids do not cause any direct harm in small numbers although large infestations can contaminate foods. They are also known to swarm over new plaster which may still be damp. Again they do not cause any harm as they are attracted by minute bacteria and moulds. They do not bite people or pets, cause any structural damage or spread disease, though some sensitive individuals may develop skin rashes.

How can I prevent an infestation?

  • Keep kitchen and food cupboards well ventilated and dry
  • Dispose of foodstuffs in these cupboards that are past their best before date
  • Check packaging before buying to make sure that it is not damaged
  • Store foods that are vulnerable, e.g. flour, semolina, etc. in washable covered containers 

How do I get rid of them?

Psocids can be controlled with insecticides, but care must be taken not to contaminate your food. If condition for psocids remain after treatment, they can still re-infest. Remove all contaminated food from the cupboards and place in an outside dustbin. You can then clean the affected cupboards with an antibacterial cleaner, dry the cupboards, then lightly spray all joins in the units with a crawling insect spray (an aerosol), not forgetting the outsides where the units adjoin the wall. Ideally we would recommend you seek professional help if you do have an infestation. Exeter City Council can offer a service for the eradication of booklice or psocids, and our Pest Control Officer will be happy to advise.


Exeter City Council charge £85.00 for psocid treatments. Payment can be made by the following, on completion of the treatment:

  • cash or cheque (made payable to Exeter City Council)
  • debit or credit card over the telephone
  • Where an account is rendered a £21.00 administration fee will be incurred

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