[Technically Speaking]

Readin’, ‘Ritin’, ‘Rithmetic’ and Lice
It’s that time of year when children are returning to school. They bring with them the stories of their great summers, their prospects for the coming year, runny noses, colds, and LICE. No matter what is done to prevent lice, this obligate human parasite never seems to disappear.

There are three species of lice that infest humans:

Crab Louse: Pthirus pubis. The crab louse is crab-like in appearance and lacks wings. It is smaller and broader than the head or body louse, i.e., about 1⁄16-inch long. It has well-formed legs with claw-like tips. The front legs are noticeably more slender than the hind two pairs. The abdomen is broad with lobe-like projections emerging from the sides. Coloration of the crab louse is dirty gray and, therefore, it is difficult to see.

Females lay two to three eggs per day and 15 to 50 eggs within a lifetime, gluing them very securely to individual hairs. The adults and nymphs feed on blood, using their piercing-sucking mouthparts, and move very little once they have settled into place. The nymphs molt three times, and development (i.e., egg to egg) requires five to six weeks. Adult crab lice live 15 to 25 days but can live only 24 hours off their host.

Crab lice most commonly infest human pubic and anal regions. Sometimes they infest the body hair, eyebrows, and facial hair of heavily-infested individuals. Crab lice use their pincer-like legs to grasp hairs.

Crab lice usually are transmitted during sexual intercourse but may also be transferred in locker rooms by items such as towels, bedding, and toilets.

Head Louse: Pediculus humanus capitatus. Head lice are about 3⁄16-inch long. ingless, they have a distinct head, short, stout antennae, and easily recognized eyes. They have stout, well-formed legs with thumb-like extensions at their tips that help the insects hold onto human hair. Adult lice vary in color from gray-black to dirty-white.

The adult female head louse produces 50 to 100 eggs that hatch within five to 10 days. The eggs are cemented to hairs very close to the scalp. The nymphs have piercing-sucking mouthparts similar to the adults which they use to feed on the blood of the host. They molt three times, becoming adults within three weeks after eggs are laid. The adults live for 22 to 23 days. Head lice can survive approximately 24 to 48 hours off infested individuals.

Head lice are considered to be the same species as body lice but prefer to infest the hair on the head of humans. When removed from this area to other parts of the body, they migrate back to the head.

Head lice are major problems in schools. Children easily transfer head lice to family members and to one another through play and sharing cubbies, hats, coats, combs, etc.

Body Louse: Pediculus humanus humanus. Body lice are virtually identical in appearance to head lice except that they are somewhat larger.

Body lice differ from head lice in that they prefer to feed on the human body instead of the head. The adult female produces 50 to 100 eggs within her lifetime. The eggs are usually glued along the seams of clothing such as underwear and hatch within about five days when the clothing is worn constantly. The nymphal stages are completed within eight to nine days but may take twice that long if the clothing is removed nightly. Body lice can survive approximately 24 to 48 hours off infested individuals.

Body lice are most common in areas where clothing contacts the body, such as the neck, shoulder, armpit, waist, and crotch. They prefer to feed in areas where the skin is soft or folded, such as at joints. They feed using their piercing-sucking mouthparts and remain attached to the clothing even while feeding.

KEY POINTS. As a pest management professional it is possible that you will be asked questions about lice. Here are some important points to keep in mind.

Contrary to what one young soldier told me many years ago, “crotch crickets” (crab lice) and other lice can’t jump, crawl or fly from the urinal or any other inanimate object to your body. Because of their unique leg structure, claws designed for clasping hair, they are unable to crawl effectively on smooth surfaces and get to a prospective host.

Louse infestations affect all social-economic classes and in no way are an indication of poor personal hygiene or a filthy environment in the home.

Individuals infested with lice should contact their physician or public health nurse in order to obtain information on products available for treatment.

Potentially lice-infested items such as clothing, hats, scarves, coats, bed linens, and blankets should be laundered or placed in a
drier for approximately 30 minutes in order to kill the lice and their eggs that may be on these items.

No pesticide applications are required to manage lice because they do not survive off the human host for any length of time. Thus, it is unnecessary to treat buildings, lockers, cubby holes, classrooms, barracks, apartments, hotel/motel rooms, hospital rooms, etc. inhabited with lice-infested individuals. Vacuums and thorough cleaning can be used to remove lice from other surfaces.

Individuals who are convinced that spraying is the only way to effectively eliminate lice or desire other information regarding lice should be referred to the National Pediculosis Association, whose Web site is www.headlice.org.

Remember that one of the basic tenants of Integrated Pest Management is customer education and what better place to start than in our schools.
The author is president of Innovative Pest Management, Brookeville, Md., and can be contacted at rkramer@giemedia.com.