Booklice identification and control

How to identify booklice

Booklice are soft-bodied, around 1 to 2 mm long and translucent white to grey-brown. They have a large head, long thin feelers and an oval body. Most indoor species are wingless. They move in short bursts, and you often see them as tiny moving specks on a pale surface, around a window or in a food cupboard.

The name is misleading: they are not true lice and do not live on people or pets.

Lookalikes

• Silverfish are much bigger, carrot-shaped, with three tail bristles. See silverfish.
• Carpet beetle larvae are hairy and slower. See carpet beetles.
• Mites are smaller still and hard to see without magnification.
• Thrips and aphids turn up near houseplants and windows.

Why they are indoors, and are they harmful?

Booklice feed on microscopic mould, mildew and starchy residues, so they appear wherever humidity is high. Common causes are new plaster drying out, condensation in a poorly ventilated kitchen or bathroom, a leaking pipe, and damp cupboards or books. A few can also turn up in stored dry food such as flour, cereal or old packets.

They do not bite or sting, do not spread disease and are not a sign of dirt. BPCA describes them as always associated with damp. They can contaminate stored food, and large numbers on bookshelves can mark paper and bindings. They are a clue to a moisture problem, not a health threat.

How to get rid of them

Dry the room out and the booklice usually go without any insecticide.

• Find and fix damp: leaks, condensation, new plaster, blocked vents.
• Open windows, run extractor fans and use a dehumidifier. Aim for humidity below about 50 per cent.
• Wipe visible mould with a suitable cleaner.
• Throw out infested dry food and keep new food in airtight containers.
• Empty cupboards, vacuum and wipe the shelves, and air books and stored items.
• In a new build, ventilate well as the plaster dries, which can take months.

When a professional is worth it

Rarely. Booklice are a damp problem first, and a pest controller cannot fix the damp. Call one only if numbers are still high after the room has been dry for some weeks, or if they are in a shop, restaurant or food store where hygiene rules apply. If you suspect a hidden leak or rising damp, a damp specialist or plumber comes first.