Head lice: The idea alone is enough to make your scalp itch. Each year, there are 6 million to 12 million lice cases in U.S. children ages 3 to 11, according to the Centers for Disease Control and Prevention. It's a year-round scourge, though the number of cases seems to peak when kids go back to school in the fall and again in January, possibly due to familial mingling during the holidays.
There are almost as many misconceptions about the parasites as there are critters. M.J. Eckert, a former school nurse and co-founder of Lice Happens, an Annapolis, Md.-based in-home lice treatment and removal service, says she once met a father who'd used a high-powered shop vacuum on his son's infested head, hoping to suck the problem away. Another family threw out a sleeper sofa in the middle of the night, convinced that it was the source of an intractable lice infestation. Neither approach worked.
First, some facts: The head louse is a six-legged wingless insect known as an ectoparasite, meaning that it makes its home on a host's surface. It's related to the body louse, which, unlike the head louse, can carry disease. The animal needs blood and a warm environment to survive. That's why it finds such comfort in the human scalp; it also likes to root itself in the nape of the neck and behind the ears.
Once it has set up shop, the insect lays pinhead-size tan or whitish-colored eggs, known as nits. The mother louse excretes a kind of glue to cement the nits to the hair shaft, close to the scalp so its warmth can incubate them. They hatch about a week later into baby lice, called nymphs. In a typical infestation, there are more nits than bugs since an adult louse will lay an average of five to 10 eggs a day and a newborn female needs only 10 days to become a mom. So the family tree grows quickly.