What lice look like depends on the species. There are 3 species of lice that can live on humans:
- Head lice
- Body lice
In this article you will find both descriptions and pictures of the different lice species. Remember that all three species have the following common features:
- They are small and have flat bodies
- They have 6 legs
- They are wingless and can neither jump nor fly
Also note that all lice go through several nymph stages before becoming adults. In these stages, they look very similar to adult lice, but are significantly smaller.
Adult head lice are 2.5 - 3 mm long and (like crabs and body lice) have wingless and very flat bodies.
Head lice can be many different colors, but they are usually white, brown or dark grey - or a color in between such as white-brown, brown-grey, light grey, etc. Their color depends on the environment they were raised in. When they have ingested blood, their color can also become more reddish.
Head lice have claws on all their legs, which they use to crawl and hold on with. They can crawl up and down hairs quickly, which is an advantage when moving from one host to another. In other environments, they are not very mobile. On flat surfaces, for example, they can barely move.
An adult crab is 1.3 - 2 mm long (slightly smaller than head lice and body lice) and can be distinguished from the other two lice species by its almost round body.
Compared to the other two lice species, crabs also have spinier front legs, thicker hind legs (two pairs) and thinner and longer claws.
Another characteristic is that the rear two pairs of legs are much thicker than the front pair. There are also large claws on the front pair of legs, which is not the case on the two rear pairs.
Body lice are almost impossible to distinguish from head lice as their anatomy is almost identical. In practice, it is only possible to distinguish between the two with a microscope.
However, body lice are slightly larger than both head lice and crabs. Adult lice measure 2.5 - 3.5 in length and are typically brownish or grayish-white.
Like many other lice, body lice can become more reddish in color immediately after sucking blood. Once digestion begins, they return to their brownish or grayish color.