Warmer global atmospheric temperatures projected for mid-century onward are expected to alter rainfall patterns, raise global aridity, and increase the frequency and severity of extreme weather events, including floods, heat waves and droughts. In the United States the frequency and severity of droughts have increased significantly over the past several decades, and global climate model analyses anticipate greater risk of drought on most continents during this century mainly as the result of elevated global mean surface temperatures and increasing aridity. In cereals, which are the dominant staple crop worldwide, drought continues to be the main abiotic constraint on crop productivity and yield, and in severe cases leads to crop failure. However, impacts from drought can also emerge from direct and indirect effects on other biotic components of the cropping system. Insect herbivores that are pests of cereals are significant in this respect because in addition to damaging crops directly, drought-induced changes to the host plant or growing conditions can affect the net impact of certain pests. But pest responses to drought can vary in direction and magnitude between species of an herbivore community but also the level (i.e., severity or duration) of drought stress. For these reasons especially, the effects of drought on cereal pests and herbivores in general remain poorly understood. Cereal systems in the Pacific Northwest (PNW) region of the United States contribute significantly to the global wheat crop. Economically important pests of cereals in the PNW include the cereal leaf beetle (CLB) and multiple cereal aphid species, including the bird cherry-oat aphid Rhopalosiphum padi and more recently, the grass aphid Metopolophium festucae cerealium. Cereal leaf beetle and both aphid species can cause extensive damage to a variety of cereal crops, but are highly prevalent in wheat grown in the PNW. While research and monitoring efforts have vastly improved our understanding, information detailing the effects of drought stress on these pests remains limited and difficult to interpret or apply within a broader management context. As a component of the USDA-NIFA-funded Coordinated Agricultural Project, Regional Approaches to Climate Change for Pacific Northwest Agriculture (REACCH PNA), this thesis aims to provide better understanding of the biotic constraints on cereal systems in the Inland PNW by investigating the effects of plant water stress on these regionally prevalent pests, using a study system in wheat and greenhouse experiments. Potential implications for pest management in PNW cereal systems under projected climate scenarios will be discussed using a regional context relevant to agriculture globally.