They've been called red bugs, jiggers and harvest mites. But when it comes to chiggers, you can't call them fun.

Chiggers were once used in biological warfare to transmit a form of typhus during World War II. Today, the six-legged larva of the bloodsucking harvest mite is more nuisance than serious health hazard. But if it's your legs they're feasting on, that's small consolation.

Chiggers are actually eight-legged arachnids, kin to spiders, ticks and scorpions. Barely visible to the naked eye, they cling to bushes, grass stems and other foliage, often in wooded or swampy areas.

The blood-red mites feed at the base of a hair follicle or a pore, injecting saliva that dissolves tissue and creates a feeding tube. The tube acts like a straw that allows them to suck up blood and partially digested cells.

In the South, chiggers are active nearly year-round, but in other parts of the country summertime is when they're busiest. Chiggers are particularly fond of areas where the skin is thin and moist, such as ankles, wrists and thighs. As any unsuspecting camper can tell you, the result is intense itching and irritation.

A few species can cause serious allergic reactions, including blister-like lesions or even asthma.

Chiggers usually dislodge within a few hours of attachment, but the itching can persist for days. So if you're itching to take a walk in the woods, apply insect repellent to take the bite out of the bug.