Understanding the Life Cycle of a Louse

Head lice are one of the most common pests that strike young families. In fact, the CDC states that children between the ages of 3-11 are most susceptible to head lice than any other age group. It is estimated that between 6-12 million children this age will contract head lice in the United States every year.  An in-depth look at the lifecycle of head lice can help parents understand how important it is to find a solution that kills head lice AND their eggs in a single treatment.


Eggs, or Nits

The first stage of life for a louse begins with a nit, or lice egg. Lice lay their eggs very close to the scalp of their human host in order to provide the heat and humidity the eggs need to grow and hatch. Eggs are yellowish white in color and are about the size of the head of a pin. With this is in mind, sometimes they can be quite difficult to detect with the naked eye. A magnifying glass can be helpful when inspecting the head for nits. They are laid with a sticky secretion that secures them to the base of an individual hair strand. This allows them to stay upright and in place, not like dandruff that flakes off easily. After an egg is laid, it will incubate for 7-9 days until it is ready to hatch.



Nymphs are immature lice, or lice that continue to grow and mature into adult lice. They will molt three separate times as their bodies grow into adulthood. This process takes roughly 7 days. After a nymph hatches from its egg, the eggshell casing will turn whiter in color and grow out with the hair strand it is attached to. If you are finding white nit casings that are ¼ of an inch from the scalp, you likely have newly hatched nymphs on the scalp. These casings need to be removed by hand or they will take up to 6 months to disintegrate.  While nymphs grow they need to be close to the human scalp to feed 5-6 times per day. They move about by crawling from hair strand to hair strand with long claws attached to each of their six legs.


An Adult Louse

The third and final stage of the head lice life cycle is adulthood. Lice will live only 30 days from the time the egg is laid until death. Fully grown lice are 2.5-3 mm in length, and about as plump as a sesame seed. Females will generally be slightly larger than males. They appear tannish brown in color, but actually, resemble the color of their host’s head as they are more transparent. If they have recently fed on human blood it can make them appear redder. Once the adult phase is reached lice begin mating. Females lay 5-8 eggs per day, every day until they die. This is why in the treatment process of head lice it is so critical to kill head lice and their eggs. If the live lice are dead, but the eggs are still present, they will hatch in 7-9 days and you will have a whole new set of head lice population to deal with. Removing lice and nits is the only method for eliminating the problem.


Did You Know?

The AirAllé® device is used by lice professionals to treat head lice and their eggs in a single, 30-minutes treatment. Lice Clinics of America technicians place the tip of the machine on the scalp, underneath the hair in various positions around the head. The AirAllé device blows heated air through its applicator tip onto the hair strands to dehydrate head lice and desiccate their eggs. There is no risk of discomfort or burning of the skin as no harsh chemicals are used. The technician will then comb through the hair to remove all dead lice and eggs. Usually, a post-treatment oil is applied as well to further protect against reinfection. The process is over 99% effective and backed by the FDA.





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