The influence of temperature on the speed of development, from egg to adult, of the coprophilous mite Macrocheles matrius is analized. The lower temperature limit for complete preimaginal development was found to be ro-12°C, and the upper limit 36-38°C. The maximum speed of development in both sexes was observed at 34°C, while the optimum was between 32°C and 360C. The most suitable mathematical expression for the speed of development-temperature relationship was found to be the logistic equation calculated for females (roo/y = 2.or/1 + e5. 19466-o.2a924x) and males (roo/y = 2.36/ l + e4.sa240-o.211009x). A comparison was also made between some values obtained at constant temperatures and at fluctuating temperatures.