Scarlet or rusty brown mite genus Trombicula, family Trombiculidae, in the order Acarina, common in summer and autumn. Chiggers are parasitic, and their tiny red larvae cause intensely irritating bites in places where the skin is thin, such as behind the knees or between the toes. After a time they leave their host and drop to the ground where they feed upon minute insects.

Chiggers are medically important and can be harmful to humans in two ways: either by the feeding activities of the larval mite, on folds of skin or the edges of hair follicles resulting in painful lesions 0.4–2 cm/0.16–0.8 in long, or by acting as carriers of disease, for example scrub typhus or haemorrhagic fever.

In the UK, they are found in enormous numbers on gooseberry bushes, grass, and low herbage in the summer and autumn.