Larvae of mites in the family Trombiculidae, sometimes called chiggers, harvest mites, or red bugs, are medically important in many parts of the world. They are known for nuisance biting and disease transmission to humans (Tsutsugamushi disease or Scrub typhus, ST). This chapter explores the biology and disease ecology of chigger mites and ST. Lastly, diagnosis, laboratory findings, treatment and prevention of ST and its trombiculid vectors are presented and discussed.