The rubber tree (Hevea brasiliensis Muell. Arg.) (Euphorbiaceae) is attacked by various species of phytophagous mites in Brazil. Studies conducted in the State of Mato Grosso showed the presence of Agistemus floridanus Gonzalez, 1965 (Stigmaeidae) on rubber trees, associated with the mite Tenuipalpus heveae Baker, 1945. The aim of this work was to study the biology of that predator in the laboratory, when fed with T. heveae as prey. The study was started with 22 eggs, which resulted in 15 females reaching adult hood. To determine the effect of mating on oviposition, 30 females were used; half of those were maintained isolated and the remaining were maintained then with males during the whole adult stage. The stage of egg was the longest, with a duration of more than 4.0 days. The total duration of the immature phase was 10.2 days. Each female oviposited an average of 38.4 eggs, with a daily oviposition rate of 2.3 eggs per female. The duration of each adult phase, the daily oviposition rate and the longevity were different between the mated females and non-mated females. All eggs produced by non-mated originated males, characterizing, in this way, the development through arrhenothokous parthenogenesis. The results showed that A. floridanus has an innate increase capacity of 13.2 times in each generation, that the average duration of one generation is 19.2 days, that the intrinsic rate of increase (rm) is about 0.16 female per female per day and that the number of females added daily to the population is 1.1.