Feeding rate and egg deposition rate of the predatory miteAmblyseius fallacis(Garman) was studied in response to the density of 3 different stages of the preyTetranyehus urticae(Koch). Predation rate and egg deposition rate depended on the density of the prey up to a maximum. The form of the curve depended on the type of prey.When the prey was in the egg stage, there was a linear relationship between number of prey attacked/predator and prey density, up to a density of 40 per leaf. When the prey was adult ♂, there was a linear response by predators to prey density up to a maximum of 40 prey per leaf. However, in contrast to egg-stage prey, as the density of the ♂ prey was further increased so was the attack rate of the predator. As the density of the ♀ prey was increased the predator attacked the eggs deposited by the ♀ rather than the bigger, active ♀.The number of eggs deposited by the predator depended on the density of the prey, up to a maximum of about 2 eggs/♀/day and then the oviposition rate leveled off. The maximum rate of oviposition was reached before maximum prey attacked.