For your convenience and immediate attention, call 800-381-6331


General Facts

Also known as psocids, booklice are tiny insects that belong to the order Psocoptera. Despite their common name, they are not true lice. Instead, their name refers to the high likelihood of finding them among old books and paper products in the home. Commonly associated with the presence of mould, booklice require ample moisture and humidity to survive. More than 70 different species of psocids occur in Canada.

Appearance / Identification

A typical booklouse is small and soft-bodied, measuring about 1 to 2 mm or less in length, with a distinctive bulgy clypeus, an area above the mouthparts. Like all insects, the body is divided into three distinct parts: head, thorax, and abdomen. The head bears a pair of long and slender antennae, which extend past the abdomen, and mouthparts for chewing. Booklice vary in colour from translucent or pale white to grey or brown depending on species. Species that infest indoor spaces most often are usually wingless, unlike their outdoor counterparts.

Photo of booklice


Booklice live in warm environments with plenty of moisture and humidity. They prefer to inhabit undisturbed spaces and are often found around books and papers, in furniture, under wallpaper, along the sides of windows, and in damp areas that support the growth of mould. Certain species of booklice will attack stored grains and infest household pantries as well as granaries, warehouses, and commercial food processing facilities. Booklice are most common and active during spring and summer.


Microscopic spores of moulds form the primary component of the booklouse diet. As a result, any mouldy plant-based material could theoretically become an attractive food source for booklice. This includes common household items such as cereals, grains, and furniture. Booklice are also known to feed on starchy materials. The appropriately named pests will consume the starch-filled paste of book bindings and wallpaper, as well as any mould contained within the paper-based items.

Life Cycle / Reproduction

Newborn booklice hatch from eggs. Known as nymphs, these developing stages look like miniature versions of adults and grow by undergoing three or four nymphal stages or moults. The length of time it takes to complete the entire life cycle, from egg to adulthood, ranges from less than a month to more than three months and depends on the temperature and humidity of the surrounding environment. Temperature also affects the number of eggs a female booklouse can produce. Females can lay about 60 eggs apiece during the summer, while the colder weather of winter results in reduced numbers of offspring.

Problems Caused by Booklice

Generally harmless and insignificant, booklice can nevertheless become an annoyance in the areas they infest. This usually occurs when the pests are left unchecked and, consequently, produce large numbers of offspring. Further problems arise when booklice infest stored food products contaminate the food with their carcasses and excrement.

Detection / Signs of Infestation

Booklice cannot survive in low humidity and therefore only infest areas rife with moisture. In fact, booklouse infestations commonly occur in stored grains with a moisture content level of at least 14%. The pests are often associated with the presence of mould, which makes it imperative to look for signs of a booklouse infestation in warm, damp, dark places around the house where mould is likely to grow.

Prevention Tips

Preventing an infestation of booklice starts with eliminating the moisture that fosters the growth of the mould on which the pests subsist. This can be achieved by reducing the level of humidity around the home with the use of dehumidifiers or fans. Keeping high-risk areas such as bathrooms and attics properly ventilated will also help with the reduction of moisture levels. Additionally, books and papers should be kept off the floor and stored in a dry place to prevent the items from becoming damp, growing mould, and attracting booklice.

Control / Removal

Taking care of any moisture issues around the house generally represents the most effective method of controlling booklice infestations. Alternative solutions, such as the use of insecticides, will not deliver optimal results if moisture problems continue to persist. Furthermore, store-bought products are largely ineffective when it comes to the control of psocids. For best results, have a pest control professional help with the detection, removal, and prevention of future booklice.