Technical Abstract: Water deficit can make otherwise arable regions less, or nonarable, from lack of life-sustaining water and it can also affect the extent to which crops are afflicted by arthropod pests. The effects of drought on host plant availability and nutrititive value influence arthropod pests of crops in a variety of ways that can benefit or detract from crop production. In the arid Sahel region of Africa (roughly from Mauritania to Sudan), for example, the effect of variable rainfall is associated with a behavioral change in the desert locust, Schistocerca gregaria (Forskål), from a solitary to highly gregarious insect, resulting in vast, mobile swarms that can devastate crop production from the Cape Verde Islands to India. Water deficit stress can also lead to host plant accumulations of proteins, carbohydrates, free amino acids, and other nutrients that favor insect growth and development, sometimes leading to outbreaks, such as bark beetles in forests, and accelerated insect infestation resulting from inadequate availability of water to field crops, as in the instances of the eldana sugarcane borer, Eldana saccharina Walker, and the Mexican rice borer, Eoreuma loftini (Dyar), on sugarcane. Insects can also benefit from drought when dry conditions suppress or exclude predator and parasite populations that would otherwise help mediate populations of pests. Water deficit in host plants can be unfavorable to insect pests because water pressure inside the plant hinders fluid uptake by plant-sucking arthropods, desiccation of insects exposed to ambient heat, and because of increases in secondary defensive plant compounds (e.g., phenolics) in and lignification of plant tissues. Coping with drought-associated pest problems, including use of drought tolerant crop varieties, soils amendments to improve water retention, heightened surveillance, and irrigation practices are discussed.