Discovered in the 18th century by Diacinto Cestoni, an Italian biologist, Sarcoptes scabiei are parasitic scabies mites that causes the scabies rash by burrowing into the skin of a host and laying eggs. The host can be a dog, cat, human, wild boar, koala, or an ape, as long as the mite has a supply of warm blood and skin to burrow into it will be a happy camper.
The life of a scabies mite is between three to four weeks. Its life begins approximately three days after its mother lays the egg in one of its burrows in the host’s skin. Once the egg hatches, about three to ten days after being laid, the scabies larvae will begin to crawl around the skin. After it molts, it enters the nymphal stage, and then quickly becomes an adult mite. A female mite has one more stage in between the nymphal and adult stages. Once a mite becomes an adult, the cycle begins all over again with a new generation.
As the mites crawl across the skin, it creates an intense itching sensation for the host. The rash is caused by an allergic reaction to the eggs buried in the skin, which also produces even more itching. Meanwhile, while the host is all but scratching its skin off, the adult scabies mites are getting their grooves on. A female and male mite will create a short burrow to mate in, and once the female mite is fertilized by a male mite the female mite will go in search of a location for a longer burrow. She then burrows into the skin and lays her eggs. The female mite uses specialized cutting tools on the front of her legs to burrow into the skin and uses the suckers on the bottom of her feet to anchor herself as she lays an egg. When the eggs hatch, six-legged larvae make their way to the surface. (Somehow, I think this is much less adorable than watching baby sea turtles hatch on the beach… but I digress.) Only about 10% of mites that hatch will survive, but during an infection the infected may host a party of 15-20 mites.
Once the larvae reach the surface, they molt and enter the nymphal stage. (Think teenagers, except with six hairy legs and no eyes.) During this stage the mites are just growing and feeding before turning into an adult mite after about three to four days. There is one more molting stage that turns the nymphs into slightly larger nymphs, and then they become adults. Female scabies mites are typically twice the size of male scabies mites to have better capabilities to burrow into the skin.
The female scabies mite spends the rest of her life after laying her eggs extending her tunnel. The male mite typically stays in his newly found bachelor pad, originally the mating burrow. When the mites die, they die in the very end of their tunnels. Scabies mite corpses lying at the end of tunnels in your skin, combined with the eggs in your skin, combined with all of the mites scurrying around your skin…. Makes me itchy just thinking about it!