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Book louse

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Book louse - Liposcelis divinatorius

Found in bird nests, libraries and insect collections, the book louse can cause damage to grain and other foods under certain conditions. Its reproduction is carried out parthenogenetically, and in a year it can produce up to six generations.

SynonymsBook beetle, Troctes divinatorius
In EnglishLiposcelis divinatorius

Domain NameEukaryotes - eukaryota
KingdomAnimals - Animalia
A typeArthropods - Arthropoda
ClassInsects – Insecta
OrderHay eaters - Psocoptera (Copeognatha)
familyLiposcelidae - Liposcelidae

In addition to the already known head, pubic and body lice, there are species that are not parasites of humans and do not pose a threat to health. However, they can cause serious damage to libraries and herbarium collections. For example, the book louse or book louse (Liposcelis decolor) is often found in its natural habitat and can cause damage to valuable grain reserves.

Book louse: characteristics of the pest and habitat

The book louse, like other members of its family, shares similarities with other species. Most hay beetles do not pose a threat to humans and are not pests. Although book louse can be confused with dust louse, they are more commonly found in homes.

What does a book louse look like?

Here are some characteristics of the book louse:

— Dimensions up to 1 mm.
— Flattened body with pronounced segmentation.
— Large head among compound eyes located on the sides.
— Various shades of color, including red, light brown, white with shades, yellow.
— Absence of any marks on the book louse, predominance of uniform coloring.
— The antennae consist of 15 segments, there are no wings.
— 3 pairs of limbs, wide hind hips.
— Differences from the dusty louse in size (up to 2 mm in the dusty louse), the presence of wing rudiments in the dusty hay louse, as well as light yellow coloring.

How to recognize a book louse?

Book lice, known for their invisibility due to their small size (up to 1 mm), do not possess wings at any stage of development. Their head is adorned with long, 15-segmented antennae, which provide better vision than other lice. The body is slightly elongated and flat, divided into a head and abdomen. Their teeth are sharp and powerful, making them dangerous pests. Book lice are also highly mobile, with the ability to easily move from one place to another and a constant need for a food source.

Where do book lice live?

The book louse is cosmopolitan and widely distributed throughout the world. It especially prefers humid southern regions and places with plenty of cover, such as forests. At the same time, the insect can be found in various places of human life, including apartments, libraries, archives, granaries and houses with poor ventilation.

Life cycle of book lice

In their natural habitat, book lice often hide in bird nests, rodent burrows, and in old logs, rotten bark, and forest floor. Their diet includes organic matter, including mold. At home, they often live in book bindings, herbariums, and can also find refuge in peeling wallpaper, cracks and little-used cabinets.

Book lice reproduce quickly and can leave up to 60 eggs per day. Their lifespan depends on humidity, temperature and access to food. They are able to live up to 53 weeks, even under starvation conditions, since they can survive for a long time without food.


The book hay beetle spreads through parthenogenesis, which contributes to a rapid increase in the population. They can reproduce all year round and can produce up to 6 generations in a year. These insects are species with incomplete metamorphosis, and the larvae develop into adults after 6 molts. Typically, the lifespan of an individual is up to 13 months, and the female is capable of laying up to 100 eggs. Most often, the eggs are located separately, which makes them less noticeable.

Causes of book lice

This type of lice is usually found in areas that are not regularly cleaned, where dust and stuffiness accumulate, creating ideal conditions for them to thrive. Having settled on bookshelves, they can begin to multiply and cause damage to valuable literature. Therefore, prevention includes cleanliness, fresh air and a dry room, as well as regular cleaning.

Interestingly, the noise created by the crowded insects can sometimes be heard in silence, which serves as a characteristic warning of the presence of lice. However, the question of where they come from initially remains open. They can enter the house through library books, archival documentation and food stored in contaminated warehouses.

As for the infestation of barns, the reasons are varied:

— Increased level of humidity in the room.
— Insufficient purification of grain from impurities.
— Lack of control over food supplies.
— Ingress of contaminated grain from other storage facilities.

The danger of book lice

Book louse can cause damage to property by feeding on food and furniture. It is especially dangerous for herbariums and zoological collections, as it can destroy the library and move to a new habitat. Although it does not pose an immediate danger to humans, its presence can cause allergies and respiratory problems due to waste products. Book lice do not bite or transmit infections, but their activity can lead to the destruction of documents, books and herbariums.

Book louse (hay louse): how to get rid of the pest?

For effective counteraction bookish lice it is necessary to take into account their high reproductive capacity - just one individual is enough to form a new colony. Therefore, eradicating them can be challenging. The desire to create unfavorable conditions for insects becomes a key aspect in their control. In the event of a mass infestation of hay beetles, it is recommended that the existing population be eliminated first, otherwise the pests may spread to neighboring houses or return once conditions inside become more suitable.

Using insecticides is an important control method, but chemicals can be expensive and pose health risks. Effective remedies against book lice are insecticides based on various substances, such as avermectin, chlorpyrifos, permethrin, cypermethrin, pyrethrum and malathion. It should be noted that due to the specific lifestyle of these insects, most types of insecticides are ineffective. In the fight against this pest, aerosols, sprays and fog are most often used, and the latter requires professional equipment and specialists.

People's methods, although less effective, can also be useful when the number of hay eaters is limited. These methods include freezing contaminated items, changing indoor temperature and humidity, and exposing contaminated items to sunlight and increasing the temperature.

Prevention it's important. The book louse chooses habitats where it can hide, and therefore you should get rid of unnecessary things and seal the cracks. Since humidity is the main criterion for insects, it is important to maintain it at a safe level, not exceeding 50%. This can be achieved by daily airing the premises, regularly checking pipes for damage, and thoroughly wiping all surfaces after wet cleaning. Since the hay beetle's main source of nutrition is mold and mildew, their appearance should be prevented. It is important to avoid accumulation of dust and storage of expired dry food. Books, documents, dried herbs, collections and herbariums are recommended to be regularly checked for the presence of pests and their activities.

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