Laboratory observation on the pilid Pomacea haustrum (Reeve, 1856), competitor and predator of Manson's schistosomiasis intermediate hosts, have shown that: Males and females reach sexual maturity after one year, copulating preferably in the morning and laying eggs at night. The time spent in these acts is variable; in the case of egglaying it depends on the number of eggs to be laid. The eggs are round, about 3mm in diameter, and have a pink color that changes with the development of the embryos. With an average incubation time of 15 to 23 days and conditioned by the temperature of the environment, they resist for 5 to 6 days immersed in water without damage to th embryos and they do not need light to hatch. The newly-hatched specimens have about 2.4 x 1,7 mm of height and diameter, respectively. The specimens bred alone grow more and survive better that when in a group. They resist for at least 90 days when left dry, remaining during this period enclosed in the shell, with the operculum hermetically closed, in hydrobiosis. In this phase, death by attack of diptera-larvae may occur.