Descrjptions of the morphological changes within each stage, of the molting and hatching processes and of the quiescent states of Amblyseius citrifolius (Denmark & Muma) were given. The larva emerged, posterior first, from the narrow end of the egg. Hatching took ca. 8 mino The duration of the ecdysis (ca. 20 to 30 min) was approximately the same for all the stages. The quiescent states were characterized by the extended, apposed palpi, by the protruded gnathosoma, by the pale, shiny coloration of the body and by a typical response to a contact stimulus. The duration of the quiescent state ranged from ca. 9.7" hr to 11.3 hr. Continuous observations on behavior indicated that more than 80% of the time in the postembryonic stages was spent resting. The number of prey (eggs and larvae) consumed by each individual in the larval, protonymphal, and deutonymphal stages were 6.3, 17.2, and 12.0, respectively. Protonymphs averaged 3.2 minutes feeding on each prey, deutonymphs 4.7 minutes, and larvae 8.0 minutes. -; At a given temperature, different relative humidities did not seem to affect the duration of the egg stage. The eclosion rates of A. citrifolius were shown in relation to saturation deficit at 16, 20, 24, 28, and 32°C. The development from egg to adult was completed in 19.7, 7.7, 5.0, and" 3.6 days at 15, 20, 25, and 30°C, respectively.The egg, larval, protonymphal and deutonymphal stages required 27.3, 10.7, 14.1, and 15.8 degree days, respectively, to be completed. Preoviposition, oviposition, and postoviposition periods and longevity were observed at 15, 20, 25, and 30°C. The fecundity averaged 31.3, 40.9, Moraes & McMurtry 3 49.7, and 41.3 eggs per ferna1e at 15, 20, 25, and 30°C, respective1y. Average dai1y egg production at 15, 20, 25, and 30°C was .75, 1.25, 2.11, and 2.51 eggs, respective1y, per ferna1e. Po11ens of Pyrus kawakarnii, Ma1ephora crocea (Jacq.), and avocado, a cornbination of Tetranychus pacificus McGregor (eggs + 1arvae) p1us~. crocea po11en, and T. pacificus (a11 stages) were the best foods for oviposition and surviva1 of A. citrifo1ius. T. pacificus (eggs + .larvae) a1so was one of the best for survivarship af the predator.