An experiment was performed to investigate the effects of overcrowding in larvalAedes aegypti(L.) and to illustrate the compensatory responses to stress in highdensity conditions. Density levels tested were 40, 160, 280, 400, 520, 640, 960, and 1280 larvae per 80 ml of solution. Some of the parameters evaluated included rates of larval development, onset and rates of larval-pupal ecdysis, pupal weights, and larval survival.Rates of larval development were drastically reduced as density was increased. Pupal weights were also reduced by overcrowding. Results indicated entire shifts in patterns of larval-pupal ecdysis as the densities were increased. Relationships between sex, survival, and weight as a function of increasing density were revealed.A descriptive model dealing with density relationships is presented. It attempts to develop some uniformity of terminology, to provide better comparisons between studies of the many aspects of overcrowding.