They are not generally any bigger than six millimetres and have soft bodies and have two pairs of membranous wings. However, in some species, there is a loss of the wings.
They tend to have eyes that are poorly developed, have long and threadlike antennae.
They run along exposed surfaces in a jerky, halting manner, and sometimes appear to hop.
These insects feed on microscopic moulds, fungi, dead insect fragments, pollen, and other starchy foods found in humid environments such as houses, warehouses, and even libraries.
Damp basements, crawl spaces, leaky and sweating plumbing, potted house plants, cereal, flour, bird nests, furniture stuffings of natural plant fibre, paste on book bindings, grains, wallpaper, etc. may harbour booklice.
These pests are usually found in books and old papers. Booklice don’t consume book material as their name suggests, but rather eat any microscopic spores of mould present in the books.
That’s one of the reasons why you’ll always find booklice and mould in the same location.