Larger pale booklouse
Trogium pulsatorium (Linnaeus)

Order: Psocoptera
Family: Trogidae
Acronym: TPU

Ecology

The larger pale booklouse is found worldwide. It is well suited to warm temperate and hot tropical climates. It feeds on animal and plant products and moulds. It is found in granaries, elevators, households, warehouses, processing facilities and museums. The larger pale booklouse infests stored grain, packaged foods, dwellings and museums where it feeds on animal and plant products such as glues, paper and fabrics. It often infests grain which is high in moisture content, feeding in groups at the tops of the grain bulk. It is associated with damp conditions.

Damage

The larger pale booklouse is a minor pest of stored grain. It does not damage sound grain. Both the adult and nymph feed on damaged grain and moulds growing in the grain. Damage is not distinct. It prefers to feed on the germ of broken kernels and then to feed on the exposed endosperm of damaged kernels. Its presence is associated with damaged grain or grain that has a high moisture content. Infestations can develop in grain that has a moisture content higher than 14%.

In museums and households, the larger pale booklouse may attack damp books, paper and fabrics. They feed on glues made from animal and plant products. Severe infestations can contaminate the product with cast skins and frass. In grain elevators they are reported to cover walkways near the source of an infestation and pose a slipping hazard. They are also reported to be the cause of inhalation allergies and are implicated in respiratory problems in people.

Life history

The adult larger pale book louse is very small, about 1.5 to 2.0 mm in length. It is soft-bodied, globular and somewhat flattened. It is yellow to light brown in color. It can be mistaken for grain mites because of its size and light coloration. Characteristic features are extremely long thin antennae which are almost as long as the body. The head is wider than the thorax and slightly narrower than the abdomen. A darker brown line runs between the eyes and up to the top of the head. The adult has short wings and cannot fly.

Breeding conditions are high temperatures and high humidity. In general, the large pale booklouse requires humidity above 60%. The female lays her eggs singly in a food source. Eggs adhere to the food source. The female may produce up to 60 eggs.

The nymph looks similar to the adult but it is smaller. The nymph is active. The conditions for development are temperatures between 27°C - 30°C and 80% humidity. The nymph moults 5 times. The larger pale book louse produces 1 generation per year.

Control

Controlling insect infestations

Images

Drawing of a larger pale booklouse