Ewing (1944) proposed the family Trombiculidae for those acariform mites commonly referred to as “chiggers.” These mites have seven distinct stages in their life cycle. Three of these stages are active (larva, deutonymph, adult) and four are inactive or calyptostases (egg, deutovum, protonymph, tritonymph). Sexes are separate and fertilization is accomplished via a spermatophore deposited by the male on the substrate. This spermatophore is later picked up by the female, and direct contact between the sexes is not involved. An excellent account of trombiculid biology is given by Sasa (1961) and detailed accounts of the stages and their duration for various species are given by Wharton and Fuller (1952), Womersley (1952) and Loomis (1956). Thus, only a brief account is given here.