ABSTRACT
Importance and physical description Bloodsucking lice are parasites of humans and many other mammals and birds worldwide, and certain species are significant vectors of disease agents. Human body lice and head lice are almost identical in appearance; however, body lice are usually about 15-20% larger than head lice. They are tiny (2-4 mm long), elongate, soft-bodied, light-colored, wingless insects that are dorsoventrally flattened, with an angular ovoid head and a nine-segmented abdomen (Figure 12.1). The eggs are small (about 1 mm), oval, white or cream-colored objects with a distinct cap on one end. Eggs are attached to clothing in the case of body lice and to hairs in the case of head and pubic lice (Figure 12.2). The head bears a pair of simple lateral eyes and a pair of short five-segmented antennae. Pubic lice are dark gray to brown in color and are called crab lice because of their crablike shape (Figure 12.3). They are distinctly flattened, oval, and much wider than body or head lice. As with head and body lice, the head bears a pair of simple lateral eyes and a pair of short five-segmented antennae. They are 1.5-2.0 mm long; their second and third legs are enlarged and contain a modified claw with a thumblike projection, which aids them in grasping hair shafts.
