Insects · Phthiraptera · Pediculidae

Body Louse

Pediculus humanus

Not Evaluated

It has not yet been assessed against the IUCN criteria. See full glossary

The human louse is a phthirapteran insect of the family Pediculidae that parasitises humans, especially children and adolescents. Its infestation causes pediculosis. Unlike the flea, this species has undergone no decline, and its distribution is worldwide. Two subspecies are recognised: Pediculus humanus humanus Linnaeus, 1758, also called Pediculus humanus corporis, and Pediculus humanus capitis De Geer, 1778.

Size

2 cm – 35 cm

Lifespan

1 years

Diet

Carnivore

Feeds mainly on other animals.

Social structure

Solitary

Lives and hunts alone, joining others only to breed.

Sighting difficulty

Unknown

GrasslandCarnivore Solitary Insect Grassland

Fun facts

There are two forms: the head louse, which lives in the hair and is a nuisance without consequences, and the body louse, which lives in the seams of clothing and has been a vector of epidemic typhus, trench fever and relapsing fever, with devastating epidemics in wars and famines.
Genetic study of the divergence between the two forms has been used to estimate when humans began to wear clothes, placing it tens of thousands of years ago.
Its eggs, the nits, are cemented to the base of the hair with a substance that shampoo does not dissolve and that has to be removed mechanically with a fine-toothed comb.
It has two subspecies, morphologically almost identical and able to interbreed: the head louse and the body louse. The difference lies in where they lay their eggs.
Only the body subspecies transmits disease, and the diseases are serious: epidemic typhus, trench fever and relapsing fever.
It neither jumps nor flies: it spreads by direct contact, and overcrowding favours its spread.
Without feeding it dies within two or three days; a female lives about four weeks on the host.
The direct harm of the infestation is trivial compared with that of the bacteria it carries.