If you have a cat or dog, and they spend a lot of time outside, you might have some experience with fleas. Fleas are extremely tiny wingless insects that can jump huge distances and have mouths designed to bite and draw blood [source: Bohart Museum of Entomology]. Fleas reproduce quickly and can have a life cycle of just a few weeks, but they may live longer depending on the conditions.
Typically, fleas attack mammals, including humans, and birds. If you get bitten by one, it's probably because your cat or dog has brought them into the house. You'll notice your pet scratching or chewing its fur, and may see "flea dirt," or tiny black specks of flea feces, in its fur. Fleas are just as happy to feed on your blood as your pet's, although they're more likely to stay for a longer time on your pet's body because they can hide in its fur.
Flea bites usually appear in clusters or lines on the skin and each looks like a dark-reddish bump ringed in pink. Just the bite could be enough to make you feel itchy. However, many people (and animals) are also allergic to flea saliva. This means that the bites cause an allergic reaction and spread into a rash. Fleas can also carry diseases such as bubonic plague, or the Black Death. Treating the itch is the simplest part of dealing with a flea infestation -- over-the-counter hydrocortisone creams or calamine lotion can help.
But unless you treat your pet and your house, you'll keep getting bitten. Fleas lay eggs in hidden places like carpets, and their larvae hatch and grow into adult fleas within a few days. Their hard bodies make it difficult to kill them directly? -- they are resistant to the scratching and can't be crushed or pinched. Usually treatment means using insecticides, but there are natural ways to eliminate fleas as well, such as dried pennyroyal and cedar oil. No matter what you use, though, it can take awhile to be completely rid of fleas. To prevent them, you can keep your pet on a flea treatment regimen, especially in the summer.
In the next section, we'll look at another skin parasite that is even clingier than the flea -- the tick.