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Booklice
Periplaneta americana (Linnaeus)

Class:

Insecta

Order:

Psocoptera

Family:

Various

Size & Characteristics:

Booklice (psocid) adults are about 1/32-1/4 in (1-6 mm) long. Booklice (psocids) have soft bodies that look like tiny termite workers; their heads are more or less bulging, with chewing mouthparts; antennae are long and threadlike with 11-50 segments; prothorax is small, looking like a neck; 4 wings, if present, are cellophane-like, and held up like a roof over the body when at rest; front wing is larger than hind wing, and has few veins. Nymphs look like adults except they do not have wings.

Color:

Varies with species, but many are brown, or creamy yellow with brown bands.

Geographic Range:

All over the world and the U.S., in which there are about 287 species.

Comparison with other species:

Psocids are often called booklice or bark lice because to the casual observer they look like some lice species. Chewing lice have short, 3- to 5-segmented antennae, and are ectoparasites of birds and mammals. Sucking lice also have short, 3- to 5-segmented antennae, and are parasites of mammals. Dampwood termite and drywood termite nymphs and workers have short, bead-like antennae.

Habitat:

Indoors: moldy books and papers, starch sizing and glue in books, damp places, sweating pipes, new plaster and sheetrock, damp spillage, wooden pallets. Outdoors: under loose, damp bark. Some psocid species are found in grain and other agricultural products. Psocids breed in wall voids, storage trunks, groceries, stored flour, rugs, paper, cartons, rope fibers, closets, cabinets and pianos. They also occur in museums and libraries.

Food:

Mold is the primary food of most species.

Biology:

Most booklice require a relative humidity of at least 50-60%, due to loss of body moisture through their exoskeletons. High humidity is also necessary for the growth of the mold on which they feed. When humidity drops too low they may migrate in large numbers. Adults usually die in winter, although the eggs and small nymphs can survive cold temperatures. When warm weather comes they can mature within 3-4 weeks. Some species do not require males for reproduction in part or all of their geographic range. Typically, outdoor species have wings, while indoor species have wings that are reduced or absent. Eggs are laid either bare or encrusted, with or without webbing. They mature in 4-6 nymphal instars.

Invasion:

Dampness and mold growth supports booklice breeding. They invade by means of stored goods, groceries, cartons, paper, construction materials.

Damage:

Booklice are nuisance pests in homes. They do considerable damage in museum collections, libraries, stored products and food processing plants. The presence of psocid bodies in house dust are believed to contribute to asthma attacks.