A series of life tables based on field observations of mortality of citrus blackfly,Aleurocanthus woglumiAshby, in a commercial orchard in León, Nicaragua (1986–1989), indicate that the solitary endoparasitoidEncarsia opulenta(Silvestri) is an important factor in the observed declines of outbreak citrus blackfly populations in 1986 and 1987. Parasitization byE. opulentawas disrupted by intensive rainfall and subsequent pesticide applications in the orchard but was restored when insecticide use was eliminated or dry weather conditions resumed. By mid-1988, survival of immatures to the adult stage was below theoretical replacement levels necessary for population increase, and populations declined to low, subeconomic densities. In late October 1988, heavy wind and rain of Hurricane Joan disrupted parasitoid activity and created conditions for potential outbreak adult citrus blackfly survivorship.E. opulentareexerted control of the population to low-density subreplacement levels within the following four host generations.