Now that school’s back in session, a few teachers are finding that they could be taking roll for inevitable-yet-unwelcome visitors in their classrooms.

Head lice.

“It’s just one of those things,” said Sonja Gaumer, nursing services facilitator for the Lawrence school district. “It’s just something that happens when you go other places: You bring ‘friends’ back with you.”

The arrival of such “friends” — small pests and their eggs, which can endure for as long as seven days before hatching — has occurred for a “handful” of students in a “handful” of schools, Gaumer said.

“It’s not an epidemic by any means,” she said. “It’s not any different from any other year.”

And the approach for students and parents to take upon discovering head lice is the same, too, Gaumer said:

• Wash the hair with an antiparasitic shampoo. That kills live lice and also can kill eggs. A natural alternative, called Lice Ice, does not contain chemicals, Gaumer said.

• Remove eggs with a nit comb, preferably a metal one. That will scrape away the eggs, she said, which “stick to your hair like glue.”

• Seven days after the first antiparasitic shampoo, repeat. That’s to take care of any eggs that weren’t removed with the nit comb.

• Vacuum carpets, furniture, your car and other areas where you’ve been in contact. Wash all clothes, bed linens, towels and other items using hot water, and use a dryer set on a high setting.

• Store items that can’t be washed — stuffed animals, pillows and the like — in a sealed plastic bag for 10 days. Lice can’t live without nourishment.

• Clean combs and brushes by soaking them in “hot, hot” water for 10 minutes.

Students looking to avoid lice altogether can take a preventative step by using shampoo that contains tea tree oil, Gaumer said. Many retailers offer such shampoos, all over the counter.

“Lice do not like the smell,” she said. “It has a eucalyptic smell, and lice don’t like that.”