The biology of Treatia indica Krantz and Khot (Acarina: Phytoseiidae), an ectoparasite of the red cotton bug, Dysderctts koenigii (Hemiptera: Pyrrhocoridae) is reported from India. The life stages include egg, larva, protonymph, deutonymph and adult male and female. At a temperature and humidity of 30.9 +/- 4.8 °C and 63.0 +/- 7.0 % in the insectary, the female mites laid an average of 1.8 eggs per day/female. The average durations of the life stages were: egg, 1.8 +/- 0.5 days; larva, 1.5 +/- 0.7 days; protonymph, 2.3 +/- 0-4 days; and deutonymph, 3.5 +/- 0.5 days. The female-male sex ratio was found to be 5: I but no mating was observed. Only protonymph, deutonymph and adults were found feeding on the skin of the host but no feeding punctures were seen. It is presumed that they feed by scraping the skin. As many as 200 mites, excluding hundreds of eggs, were occasionally found on a single host under pronotum and on the dorsal side of abdomen below the wings. With moderate infestations no significant mortality was found in the hosts.