The effect of three temperature degrees (20, 25 and 30ºC) and 65±5%RH. on the biological aspects ofEutetranychus africanus (Tucker) were investigated. Threshold of development (t) and accumulated heats (k) for total immature duration development of E. africanus (Tucker)were calculated to be 15.7 ºC and 48.8 degree-days (DD`s, female). Development of egg stage required 61.6 & 65.6 dd`s above 13.4 ºC while generation period demanded 162.540dd`s , above  13.02 ºC  and this value 155.9 dd`s above 8.05   ºC for Longevity.The accumulatedthermal heat units (T.U.) or effective degree-days estimated through the mite activity time. The aim of this part of investigation is to establish the velocity constants (i.e the relationship between temperature and speed of development).