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Image via Wellcome Images.
by Kevin Mackenzie.
Scanning electron micrograph of a nit or head louse egg (coloured green) attached to a strand of human hair (coloured brown).
Head lice feed on human blood and live in close proximity to the scalp. Female lice lay eggs in sacs that attach firmly to individual strands of hair near the base of the hair shaft.
Most will hatch within seven to ten days, and the newly emerged immature louse (nymph) will then need to feed on blood to survive. The width of the image is 1.5 mm.
A head louse develops from an egg to an adult in 16 to 21 days. Head lice start out life as eggs, which are attached to the hair near the scalp to stay warm.
Eggs usually hatch within seven to ten days, and the newly emerged immature lice (nymphs) then need to feed on blood from the scalp to survive.
Nymphs go through three stages before maturing into adults, which can take around a week.
The adult louse is about the size of a sesame seed and has six legs with claws that help it cling on to the hair.
Adult lice can live for three to four weeks, but will only survive for one or two days away from a person’s head.