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Trombiculidae

life science Maturity 11-13 Next article →

Tiny mites called Trombiculidae live all around the world. In North America, many people know them as chiggers. In Britain, they are called harvest mites. They are also known by names like berry bugs or red bugs. These mites are very small and hard to see. They are nearly microscopic, measuring only 400 micrometers across. This is about 1/60 of an inch. Most of them have a bright chrome-orange color. They like to live in forests and grasslands. You might find them in damp areas near lakes or berry bushes. They also live in dry places like lawns and parks.

Trombiculid mite larvae attached to human skin
Trombiculid mite larvae attached to human skin

These mites go through a life cycle with four stages. They start as eggs and then become larvae. The larvae are the only stage that acts as a parasite. This means they feed on other living things like humans, rabbits, or even box turtles. To feed, the larva does not actually bite like a flea. Instead, it injects digestive enzymes into the skin. These enzymes break down skin cells to create a hardened tube called a stylostome. The larva then sucks up the digested skin through this tube. This process causes red bumps, hives, or a skin rash.

Chigger bite
Chigger bite

After the larva finishes feeding, it drops to the ground. It then grows into a nymph stage. This stage has three parts called the protonymph, deutonymph, and tritonymph. The deutonymph grows an extra pair of legs to have eight legs in total. Finally, the mite becomes an adult. Unlike the larvae, adult mites are not parasites. They are independent predators that eat small insects and plant material. They often live in the soil or in compost bins. Because they do not bite humans, the adults are harmless.

Harvest mite cycle
Harvest mite cycle

People have known about these mites for a very long time. Records of chiggers go back to sixth-century China. In 1758, a scientist named Carl Linnaeus described one species. Later, Henry Ellsworth Ewing described them as a separate family in 1944. In North America, the most common species is Trombicula alfreddugesi. It is found from the Atlantic coast to the Midwest and down to Mexico. In the UK, the most common type is Neotrombicula autumnalis. This species lives from Western Europe all the way to Eastern Asia.

TrombiculosisSores
TrombiculosisSores

If you are in a warm, humid place, you might encounter them. In the United States, they are most common in the South and Midwest. They are hard to find in deserts or high mountains. In the UK, they are common in August, so people call them aoûtat in French. In some parts of East Asia, a specific mite can carry a bacterium. This can cause a sickness called scrub typhus. This sickness can cause a fever or a headache. Most chigger bites in North America just cause itchy welts that heal on their own.

Harvest mite cycle
Harvest mite cycle
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🖼️ Images & Media (4)
File:Harvest mite cycle.svg
Harvest mite cycle.svg
File:Chigger bite.svg
Chigger bite.svg
File:TrombiculosisSores.jpg
TrombiculosisSores.jpg
File:Trombiculid mite larvae attached to human skin.jpg
Trombiculid mite larvae attached to human skin.jpg
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