Tiny white insects on walls and books: are they booklice?

Tiny white insects on walls in Singapore: are they booklice?

If you see very small, pale insects on a wall, a shelf or the pages of an old book, booklice are one likely answer. Penn State Extension describes booklice as small, soft-bodied, wingless insects about 1 to 2 mm long. Most are light to dark tan, but they can also be grey, dark brown, orange-brown or nearly clear. The same page notes that they are sometimes confused with bed bugs, which are usually larger and rounder.

The University of Minnesota Extension covers booklice under their wider group name, psocids, and describes them as generally white, grey or brown.

To check, look closely at where they gather and what is nearby. Soft, wingless insects clustered near a damp patch, a mouldy corner or a stack of stored paper fit the picture. If you cannot tell what they are, or you also have bites, have them identified before you treat anything.

Why they appear: damp and mould

Booklice go where the mould is. Penn State Extension says that indoors they are found in humid, damp, generally dark areas, where they feed on fungi and mould, including mould on paper, books and stored grains. So insects in damp books are a good reason to check that shelf, cupboard or storeroom for moisture.

The University of Minnesota Extension adds that in homes they are typically found in damp, warm, undisturbed places where mould and fungi grow. Places worth checking include wardrobes and cupboards against outside walls, the space under the kitchen sink, boxes left on the floor and a household shelter used as a storeroom.

In Singapore, this matters. The Meteorological Service Singapore describes "high and uniform temperatures, and high humidity all year round". Rooms and cupboards that stay closed, with little air moving through them, can stay damp enough for mould to grow on walls, paper and fabric.

For mould on walls or ceilings, see our mould questions.

Are booklice harmful?

Not to you or your pets. Penn State Extension says booklice do not bite, do not carry disease and do not directly damage paper products or fabric. Their droppings can contaminate stored food, so dry goods kept in an affected cupboard are worth checking.

The University of Minnesota Extension says they do not harm people or pets and are mostly a nuisance.

The more useful thing to deal with is what brings them in. A room damp enough for booklice is damp enough for mould, and mould can mark walls, books and clothes. Treat the insects as a signal to find and fix the damp.

Getting rid of them: dry the area

The fix is about moisture, not chemicals. The University of Minnesota Extension says the most effective way to manage booklice is to reduce moisture, and that they do not survive below 45 to 50 per cent humidity. It suggests using a dehumidifier or fan to air out rooms, storing boxes, books and papers off the floor, and vacuuming up small numbers.

In practice, that means:

• Find the source of the damp, such as a leak, a wet wall or a cupboard with no airflow, and fix that first.
• Run a dehumidifier or a fan in the affected room, and leave wardrobe and cupboard doors open for a while each day.
• Take books and papers out, let them air in a dry room and put them back on shelves, not the floor.
• Vacuum shelves, corners and any insects you can see.

For the mould itself, see our guide to remove bathroom mould. For general cleaning around the home, the National Environment Agency (NEA) publishes general cleaning guidelines for residences.

Do you need pest control?

Usually not at first. The University of Minnesota Extension says insecticides are normally not necessary and are not effective if moisture is still a problem. Spraying a damp cupboard without drying it leaves behind the conditions that brought the booklice in.

A pest control company is worth calling in two cases: if the insects keep coming back after the area has been dry for a while, or if you are not sure what they are. A company can identify the insect and tell you whether anything beyond drying and cleaning is needed. For more, see our pest control questions.

If the bigger job is the mould rather than the insects, a cleaning company may be the more useful call once the damp is fixed.

Choosing a pest control company

Tell the company what you have seen, where you saw it and what you have already done to dry the area. Ask whether they will identify the insect before suggesting any treatment, what the visit includes and whether the damp should be fixed first. The price depends on the job, so ask for a written quote that lists the work. For more on comparing companies, see our guide on how to hire a pest control company.

Questions