Developmental times (egg to adult) and fecundity of the European house dust mite, Dermatophagoides pteronyssinus (Trouessart), were determined for various temperatures that normally occur in the mite microhabitat in homes. Egg-to-adult developmental times were 122.8 +/- 14.5, 34.0 +/- 5.9, 19.3 +/- 2.5, and 15.0 +/- 2.0 d (means +/- SD) at 16 (61 degrees F), 23 (73 degrees F), 30 (86 degrees F), and 35 degrees C (95 degrees F), respectively. Developmental times of individual life stages were consistent proportions of the total egg-to-adult developmental times regardless of temperature. Duration of the egg and protonymphal and tritonymphal life stages were 20-26% of the total development times and for the larval stage, 28-33%. At 23 degrees C, females lived 31.2 +/- 11.1 d and produced 2.5 +/- 0.7 eggs per day during a reproductive period of 26.2 +/- 10.7 d. By comparison, at 35 degrees C, females produced 3.3 +/- 1.3 eggs per day, but female longevity and the reproductive period were reduced to 15.5 +/- 9.6 and 11.6 +/- 6.4 d, respectively. During a lifetime, females produced 68.4 +/- 30.4 and 48.0 +/- 29.6 eggs at 23 and 35 degrees C, respectively.