The comparative susceptibility of Biomphilaria alexandrina and Lymnaea cailliaudi to the action of the dry powder of some plants was determin ed. The aqueous suspensions of the dry powder of Agave kerchovei and Agave heteracantha showed LC. at 110 ppm and 190 ppm respect ively. The potency of the dry powder of both plants against B.alexand rina and L.cailliaudi has been found to be stable under the effect of sun-light, temperature 30°C, mud and alkline pH, but slightly diminished under the effect of acidic pH and low temperature possible availability of both plants render them as possible molluscicides of economic import ance.