MadSci Network: General Biology

RE: chigger lifecycle

Area: General Biology
Posted By: Mark Friedman, Undergrad, Biology
Date: Mon Oct 14 08:17:40 1996

MadSci Network: General Biology

I'm sure you aren't the only one who has faced the uncomfortable itching sensation of a chigger bite. Unfortunately, chiggers are so small that most people have no idea what they look like. Chiggers range in length from 0.1 to 16 mm. Certain species of chiggers have eyes, while others have none. On most chiggers, one can see spiracles, or breathing pores, which are found at the base of the first pair of appendages or elsewhere on the front part of the body.

Various types of chiggers attack humans, either as parasites or as carriers of disease. Attacks of chiggers often result in a dermatitis accompanied by intense itching, which I'm sure anyone can attest to whose ever lived in the South. In North America the common chigger that attacks humans is Eutrombicula alfreddugèsi (also called Trombicula irritans). This species occurs from the Atlantic coast to the Midwest and southward to Mexico.

The tiny larvae easily penetrate clothing. Once on the skin surface, they attach themselves and inject a fluid that digests tissue and causes severe itching. The surrounding tissue hardens, forming a tube. After feeding, the larva drops to the ground and sheds its skin, first becoming a nymph, then an adult. Contrary to common belief, chiggers do not die after biting a human. Rather, they enter the adult stage of life

Hopefully this answers your question.


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