Just the mention of them makes you scratch your head.
"They are tiny insects that live on human hair and feed on blood," said Beverly Sparks, a University of Georgia Extension Service entomologist. "They inject saliva into the skin that causes itching."
For many Georgia school children this spring, they're a very real itch. For parents, they're a nightmare.
Head lice are usually more prevalent among smaller children because they're transmitted by direct contact. Smaller children usually have more close contact with each other than older children or adults.
"Lice can also be transmitted through contact with clothing or other personal items," Sparks said. "If a person had head lice and had on a hat, and you put the hat on right after they wore it, you could get them.
"Head lice can survive off of a host for only about 48 hours," she said. "So it takes pretty close contact to get them."
African-American children are usually spared the agony of head lice, thanks to genetics.
"Head lice have front legs that look like a fish hook. That's how they hold on," Sparks explained. "Caucasians have round hairs that make it easy for them to grip and hold on. African-Americans have more oval, flat hairs, and the lice can't anchor themselves."
How do you know if your child has head lice? And how do you stop them from spreading?
"In school situations, when we identify head lice we recommend that everyone be inspected. We treat those who are infested," Sparks said.
"Some schools have a 'no-nit' policy," she said, "meaning a child can't come back to school until no nits, or eggs, are visible."
If your child comes home with head lice, don't panic. The cure is simple and can be taken care of overnight.
"Use shampoos containing insecticides to kill the lice," Sparks said. "In addition, you can physically remove them with a lice comb, or use a combination of insecticide-containing shampoo and combing. Repeat the shampoo treatment in seven to 10 days.
"We recommend that along with the hair treatment you treat the materials the infested person contacts, like pillows, bed linens, towels, brushes and combs," she said. "Wash linens with soap and hot water and dry them in a dryer. Clean combs and brushes with boiling water or lice shampoo."
There's really no season for head lice.
"Lice outbreaks occur when large numbers of kids come together," Sparks said.
That makes schools the perfect breeding grounds.
If you think your child has come into contact with head lice, Sparks said, "Inspect, use the comb and shampoo treatment and follow up with daily hair inspections for 10 days. It's no big deal."