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When people speak of chiggers or redbugs, they're referring to the same creatures -- harvest mites, of which at least 1,800 species are known. Though the larvae are bright red, giving rise to the name redbugs, chiggers aren't actually insects. Mites, along with spiders and ticks, are members of the Arachnid class of arthropods. Barely visible to the naked eye, chigger larvae are perhaps best known for the itchy, red welts they leave behind.
Harvest mites spend winter buried in the soil and come out with the warmth of spring to lay their eggs. Females lay their eggs in clusters, so thousands of chiggers may emerge from a single patch of grass. The larvae hatch as tiny red mites with three pairs of legs. They scuttle up to the tips of tall grasses and brush, waiting for a host to pass by. Chiggers are parasitic only during this larval stage. Once they've eaten their fill, they morph into eight-legged nymphs. Nymphs and adults eat insect eggs.
The Ankle That Feeds
Although they cling to any passing host, chiggers have a preference for tender, thin-skinned places where clothing constricts, such as ankles, waistbands and groins. Contrary to myth, they don't bury into your skin -- they're too small to do that -- and they don't drink your blood. Once they've attached to your skin, they bite and release a digestive enzyme that dissolves the skin cells around the bite so they can feed. When they've had their fill, they fall off. Often the only sign you've been bitten will be itching and redness, the result of your body's immune system fighting against the chiggers' skin-eating saliva.
Around the World
Although their bites may be irritating, chiggers in North America aren't known to spread diseases. North American chigger species evolved to feed primarily on birds and reptiles, biting humans only opportunistically. Southeast Asian chigger species, however, evolved to prey on mammals and are responsible for spreading a disease known as scrub typhus. The disease isn't particularly deadly but causes lymph glands to swell and leads to headaches and fever. On the plus side, humans aren't particularly allergic to the saliva of Southeast Asian chiggers, so the bites don't itch.
An Ounce of Prevention
Because chiggers lay their eggs in clusters, spraying insecticides can be ineffective, and it kills a number of helpful bugs in the process. Mowing down tall grass and brush removes ideal egg-laying habitat. If you have to be in areas of thick vegetation, especially during humid summer months in the Southeast or Midwest, the best way to prevent getting bitten by chiggers is to wear long sleeves and pants tucked into boots, insuring all of your skin is covered. You gain additional protection by using chemical insect repellants on your skin and clothing.
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