Head Lice (Nits)
Pediculis humanus capitis
Head Lice are small wingless insects, pale in colour around 3mm in length or about the size of a small flea. They are structurally similar to a flea as they are dorsally flattened (really thin) to allow them to move freely through the forest of hair on the human scalp. When the louse has a blood feed it becomes dark reddish brown.
The eggs are very small, white in colour with a dark centre.
Head Lice have a 3 stage life cycle, eggs, nymph, adult with 3 moults during the nymph stage. The eggs are laid on the head, glued to the individual hair shaft. An infested head could have thousands of eggs, congregated around the ears, the back of the neck (long hair) and on the crown. The live eggs are called “nits” and hatch between 6 and 10 days. Once the eggs hatch they are called Nymphs and begin to feed immediately and undergo 3 moults in 9 days to become mature adults. The nymph requires a blood meal in between each moult. The entire lifecycle of Head Lice from hatching is 30 days.
The adult males and females reach sexual maturity in 10 hours and frequently mate with the female laying 3-4 eggs per day.
Head lice live on the human head. A lot of people think that lice will infest bedding, hats, furnishings, clothing, hair brushes etc however the lice requires blood to live and feeds 4-5 a day.
Generally the louse will survive off a host for 6 hours in dry climates, or 12-24 hours in humid climates. Head Lice don’t jump, nor do they fly – they will move from host to host primarily through head to head contact. They are found worldwide and it is thought that they have been around with humans since the beginning.
Quite simply their food is human blood. Each stage requires a blood meal to survive and usually feed 4-5 times per day.They must feed at least every 6 hours or they will begin to desiccate and die. When they bite they inject saliva containing an anticoagulant into the wound to enable the free flow of blood.