Julie has taught high school Zoology, Biology, Physical Science and Chem Tech. She has a Bachelor of Science in Biology and a Master of Education.
Your head is really itchy and tickly. You notice red bumps on your head and neck. Upon closer inspection you see some white clumps in your hair. Is it dandruff? A rash? I have bad news for you. It's neither of those things. You, my friend, have lice. Specifically you have sucking lice, which belong to Anoplura, a suborder containing 500 species of lice. The name 'Anoplura' means 'unarmed tail' in reference to this group missing cerci (which are appendages at the back of some insects).
A louse (which is the singular for lice) is a tiny, wingless insect that is parasitic (meaning it benefits at the expense of another). There are different groups of lice, and the Anoplura group, as was mentioned a moment ago, is known as the sucking lice.
There are also biting and chewing lice that look a little different and have different hosts compared to the sucking lice. For example, many species of the biting/chewing variety focus on birds, whereas the sucking lice stick to mammals and include the species that is currently having a grand old time on your head.
Let's check out the life cycle of sucking lice. Remember, there are 500 species of lice within the Anoplura group, so let's hone in on the ones that are crawling on your head, which are aptly named head lice, or Pediculus humanus capitis if you're into fancy scientific names.
Let's begin with the egg, which is often referred to as a nit, and is laid near the scalp, at the base of a hair shaft. Nits look a lot like dandruff, and are a yellow or white color. The nits remains attached to the shaft through a cement-like material and hatch after 6 to 9 days.
After the eggs hatch, the lice are called nymphs, and look just like miniature adults. Nymphs will molt, or shed their skin as they grow, three times before they become an adult. They will drink the blood from their human host using their curved teeth to penetrate the skin and then suck your blood two times a day. After about a week, the nymphs reach adult-size.
Once the louse is a mature adult, the females will lay 10 eggs a day (or about 60 during her life). Lice are small and adults are only about the size of a sesame seed (that's why it's so hard to find them in your hair)! The adults will continue to feast on your blood, until they die (lice typically live around 30 days).
So far we know that one of the members of the suborder Anoplura is the head louse, and it lives on the human head, but what about the other 499-ish species? As mentioned earlier, this suborder sticks to mammals and can infect 18 to 20% of all mammal species. This group is well suited to mammals. For example, members of Anoplura have specialized claws that help them grasp mammalian hair as well as mouthparts that help them bite and obtain blood.
So, other than your head, where can other species that fall into the Anoplura suborder be found? The short answer is around 830 mammals, including rodents, cows, sheep, goats, deer, primates, pigs, horses, dogs, and giraffes, among others. While the list is long, there are mammal groups that are not bothered by Anoplura lice (that's not to say other types of lice don't bother them). Some unaffected by Anoplura include whales, elephants, and bats.
I bet you're really itchy now. What you are experiencing is one of the 500 species belonging to the suborder Anoplura, or sucking lice, crawling around in your hair. A louse (or plural: lice) is a wingless, parasitic insect that feasts on blood. The life cycles vary, but we focused on the life cycle of the type of louse found on humans. Of course, Anoplura lice can affect other mammals too (around 20% of mammals are affected by this group), including cows, horses, dogs, pigs, giraffes and many others. Take a look at the table to review the life cycle.
|Egg or Nit||Eggs are laid near the scalp and hatch after 6 to 9 days.|
|Nymph||The nymph looks like a miniature adult and molts three times. The nymph sucks the blood of its host and becomes an adult after about 7 days.|
|Adult||Adults are the size of a sesame seed, and females can lay 10 eggs a day. Typically, lice live about 30 days.|
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