The biology and behavior of Caloglyphus anomaltus was investigated by culturing them in microcells on agar with Bonner s medium and Escherichia coli, at 100 % R. H. and at controlled temperatures of 15, 20, 25, 30, and 35° C. 20 and 25° C appeared to be near optimum, based on the average percentage of eggs hatched, 72.2 and 78.2 respectively, against about 50 % for the higher and lovver temperatures. The life cycle was completed in 9·3 and ro days on the average, while it was about 40 % longer at 15° and 40 % shorter at 30°. No hatching occured at 35° which was apparently lethal to the embryos. The life cycle comprised the egg, larva, protonymph, facultative hypopus, tritonymph and the adult. The morphology of the developmental stages including the hypopus has been described for the first time in this mite. C. anomalus has high fecundity, laying a total of 459-II79 eggs with oviposition lasting for 2-4 weeks. Occasionally the eggs hatch inside the mother, a conditon similar to that observed in C. moniezei.