Intraguild interactions occur when predators that share a common class of prey also engage in predator–prey interactions with each other. Such predatory interactions can occur within species (cannibalism) or between species. Unlike nonguild predation in which food is the principal benefit, both intraguild predation (IGP) and cannibalism are doubly advantageous to the predator because they provide food and eliminate potential competitors. In this chapter, we examine the expression of various forms of IGP and cannibalism among the predatory Heteroptera. The available literature on IGP and cannibalism and their consequences for biological control and integrated pest management are discussed. We also discuss the behavior of a reduviid. Sinea diadema F., as a model for studying the effects of hunger, kin recognition, and injury on the expression of cannibalism.