How to get rid of booklice

Booklice, also known as bark lice, plaster mite, and bark flies are a common problem in the UK. Increased numbers of HSDonline customers are contacting us on how to eradicate them from their home.

Booklice (also called Barklice)

Where do book lice come from?

The booklice is tiny grey or brown insects generally found in damp, warm, undisturbed areas in buildings, where it feeds on microscopic mold and mildew. This little bug appeared on earth approximately 295–248 million years ago. Contrary to popular opinion, book lice do not bite humans or animals, spread disease or damage household furnishings, however they can sometimes cause mild skin irritation.

Outdoor species are often referred to as bark lice, since they are normally found under tree bark or leaves.


What do book lice look like?

  • Adult booklice are soft-bodied ‘greyish-white’ insects about 1-2mm long and are usually wingless.
  • Nymphs are very small and often appear transparent, becoming more opaque with age.



Booklice are all female, with development occurring from unfertilized eggs. Each female is capable of laying in excess of 60 eggs, which are placed either in clusters or laid singly. The young white nymphs then emerge to feed on molds and mildews until they reach adulthood – a process that takes between four to nine months.

Up to eight generations of bark lice per year can be produced, with adults dying in cold weather and eggs hatching the following spring. Outbreaks are common when long periods of humid weather is accompanied by warm temperatures.

Booklice avoid light and prefer temperatures of 25°C to 30°C, with relative humidity’s of 75-90%.

Dehumidifiers for home can help eradicate booklice by reducing the high humidity levels they prosper in.


What are Psocids?

Psocids or booklice are common but harmless household bugs between 1 and 2 mm long, which survive in dry powdery foods. They prefer to live in dark, warm, humid places such as the folds in packaging in food cupboards, and dislike light or disturbance. They feed on a wide variety of dry food products such as flour and also the microscopic moulds that develop in humid conditions.

They may live for over six months during which time the female may lay up to 100 eggs. Research has shown that the sort of Psocids (there are several different species) which cause problems in homes are rarely found where food is produced.


What Causes these bugs?

They prefer areas with high humidity but can tolerate dry conditions for some days. The kitchen is likely to provide the conditions they need and fitted cupboards provide the darkness which attracts them. Some food products, including flour, naturally contain moisture. Moisture in the home can be caused by not having enough ventilation in the kitchen or bathroom.

In warm conditions they can rapidly increase in number. This is most likely to occur during the summer months when temperatures are higher, leading to their discovery in the autumn.


How to prevent a booklice infestation ?

It is best to keep all dry foods in cool larders or cupboards with ventilation. If this is not possible make sure that your cupboards are always free from condensation and damp. If you notice that condensation occurs in your kitchen, particularly during cooking or washing, open your windows. If the problem is continual it may be necessary to take additional precautions.

Advice on preventing condensation may be sought from the Private Sector Housing Team. If you discover any insects, do not use an insecticide because of the danger of contaminating your food. The best method to get rid of booklice is to remove and dispose of all the affected food.

  • Clean the cupboard by using a DRY cloth, or by vacuuming.
  • Empty the contents into an external dustbin.
  • Make sure the cupboard is completely dry before replacing any foods.
  • This may be achieved by using a warm air blower like a hair dryer.


Prevention is always better than cure. Store dry foods in a cool dry place.

 How to get rid of booklice?

Chemical pest control is required. You should ventilate and dry areas with a dehumidifier fan and apply for below products to the specified areas.

1. For use in sensitive food areas: remove all food from cupboards, spray Protector Natural Insect Killer -let it dry- wipe down with a dry cloth and pack food back.

2. For use on soft furnishings use the efficient Protector C for a long lasting residual kill effect.

Infestations will usually disappear during late autumn when rooms are artificially heated and kept dry, but many people have found that using mothballs or mould-control products will help clear up an infestation more quickly.

I finish with one of our hundreds of positive feedbacks about the Protector C

An amazing product. It goes to work immediately. I cannot recommend it highly enough. I now have peace of mind and no beetles – yipee!

(27th Dec 2012 – J Dyson, Yorkshire)


**Thanks to Josh Hulme (business development executive /Pest Control specialist) for his interesting guest post**

Josh is also the author of ”Pest control, rats are a common problem”  and “Hotels and bed bugs: prevention Vs eradication


5 thoughts on “How to get rid of booklice

  • May 18, 2013 at 12:24 am

    Thank you a lot for sharing this with all people.

    • May 18, 2013 at 12:08 pm

      It’s important to speak about this topic as it can be a very frustrating problem.

      Thanks for the support Nikki!

  • May 28, 2013 at 3:51 pm

    Psocids are really delightful, harmless creatures and I fail to understand why anyone would wish to do them harm. They are unpretentious, fungus eaters which brighten an entomologists day

    • June 28, 2013 at 4:59 pm

      Thank you for your recent comment Chris,
      We see where you are coming from but booklice can be nuisance and an irritating problem for some people.

      You said “I fail to understand why anyone would wish to do them harm”, fair enough.
      (Hope we are going to convince you! :-)
      Psocids are harmless creatures in a way; because besides damaging books, they also infest food storage areas, where they feed on dry, starchy materials so it doesn’t make it very hygienic…
      So for this “simple” reason, they are kind of a nuisance really, what do you think?



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