The effect of increased densities on mortality and fecundity ofTyrophagus putrescentiae(Schrank) adults was studied with a yeast granule as the food source. Contest competition operated when adult stages competed for the yeast granule (the slope had abvalue of 0.1). Survival of females exceeded that of males under crowded conditions. The oviposition rate of the females decreased with density. Density and consumption time were curvilinearly related, suggesting that the effect on mortality and fecundity was caused by the mites competing for feeding space on the yeast granule.