Insecticides are a vital component of any good pest management system. With a diminishing supply of new insecticides entering the market place each year and with the supply of registered compounds diminishing as well, either as a result of additional regulatory constraints or ineffectiveness due to resistance development, it becomes even more essential that pest management specialists devise strategies to maintain the effective life of the currently-available insecticides. Resistance is one of the main reasons for the declining supply of effective insecticides. This emphasizes the need for a concentrated effort to focus on Insecticide Resistance Management. An understanding of the principles of resistance development is vital to accomplishing this task. This will require a better and more complete understanding of the biology and ecology of pest species and how to utilize this information to their detriment. Two major cotton pests, the tobacco budworm and the pink bollworm, are discussed to illustrate the level of resistance occurring in field populations, the potential for resistance development, and ways of circumventing resistance by utilizing information on the biology and ecology of these pests to develop integrated pest management systems.