What are these tiny white bugs? Could they be booklice?
Often, yes. Booklice are tiny, pale, do not bite and feed on mould in damp air, which is why new builds get them. They fade as the air dries: it takes patience, but it works.
If they are very small, pale or greyish, and running about on books, window sills, cardboard or bathroom walls, booklice are a likely answer. They do not bite people, they do not feed on blood, and they are not bed bugs. They eat the microscopic mould that grows in damp air, so they are a sign of humidity, not of a dirty home.
That is also why they are so common in new builds. Fresh plaster, concrete and screed hold a lot of water and give it off for months as the building dries. Booklice arrive with the damp and fade as it goes. If you have been living with them for months, the way out is slow, but it is real: dry the air and they go with the damp.
Booklice, bed bugs or mites?
- Booklice: tiny, soft and pale white to light brown, with six legs and a head that looks a bit big for the body. They run in short, quick bursts. You find them on books, paper, cardboard, dry food packets, window frames and walls with condensation.
- Bed bugs: flat, oval and reddish brown as adults, about the size of an apple seed. Young ones are paler but turn reddish after feeding. You find them in mattress seams, bed frames and headboards, with dark spots of droppings nearby. See the bed bugs guide.
- Mites: eight legs and usually so small you see them only as moving specks, or not at all. Dust mites cannot be seen without a microscope.
A sharp phone photo in good light, with a coin beside it for scale, helps a lot. The Shoo scanner names booklice too, and says plainly when it is not sure. If it is not sure, compare with the booklice guide, or press one onto clear tape and show it to a pest professional.
The plan: dry the air, then give it time
- Air the rooms every day. Open windows for a while, especially after cooking, showers and drying clothes. Keep trickle vents open if your windows have them.
- Run a dehumidifier in the worst rooms and empty it often. Steady, lower humidity over weeks matters more than one big blast.
- Keep the heating steady. Cold rooms and cold walls collect condensation. Low, even warmth helps a new building dry.
- Pull furniture a little away from outside walls so air can move behind it. Mould grows in still corners.
- Dry or clear what is stored. Air books and papers from damp cupboards, move them to a dry room, and swap cardboard boxes for plastic. Throw away dry food that is damp or mouldy and keep the rest in sealed containers.
- Wipe away any mould you can see, then keep that spot dry.
Then be patient. Numbers drop as the mould they feed on dries out, but a new build that is still drying can take many months. It is the drying that ends it, not a product.
Why sprays and powders let people down
Lots of people try diatomaceous earth because they have read it is natural, harmless and kills everything. It is not that simple. It is a fine dust that can irritate lungs and eyes if breathed in, and it works by drying insects out, which it does poorly in the damp rooms where booklice live. If you use it, follow the label and keep it away from children, pets and anyone with breathing problems. More in is diatomaceous earth safe?
A professional spray can knock numbers down for a while. But while the walls stay damp, the mould grows back and so do the booklice. Put your effort into air and moisture first.
Pregnant, a baby at home, or asthma? Booklice do not bite, and the main fix is drying the air, so you can leave sprays and dusts out altogether. If someone suggests a product, read the label first and ask a pharmacist or doctor if you are unsure.
When to get help
If you have aired, heated and run a dehumidifier for a couple of months and numbers have not dropped, look for a hidden source of water: a slow leak, a blocked gutter, a damp patch behind a unit, a cold spot where insulation is missing. A surveyor or damp specialist can find moisture you cannot see, which is often more use here than another pest visit.
In a new build, report damp to the builder in writing with dated photos, and to the new-home warranty provider if you have one. If you rent, tell your landlord the same way. Larger, faster silvery insects in the same damp spots are likely silverfish: see do silverfish mean my home is dirty?
More questions
Do booklice bite?
No. They feed on mould, not on people or pets.
Will they ruin my books?
They graze the mould on paper more than the paper itself, but damp books can stain. Dry them and store them somewhere airy.
I found them in a packet of flour. Is it ruined?
Throw that packet away, wipe the shelf, and keep dry food in sealed containers somewhere dry.
Are they living in my bed?
They can wander onto bedding near a damp wall, but they do not feed on you. If you also have bites or dark spots on the mattress, check for bed bugs.
If a product label ever says something different from this page, follow the label. Safety and labels