Technical Abstract: Many kinds of arthropod natural enemies (predators and parasitoids) inhabit crop fields in Arizona and can have a large negative impact on several pest insect species that also infest these crops. Assassin bugs are among the largest insect predators found in cotton and other field crops in Arizona and are considered “top” predators because they themselves have no natural enemies. These ambush predators feed mainly on larger insects pests such as caterpillars and plant bugs. They may also attach other predators in the system and this has been shown to disrupt the biological control of some pests such as aphids. This extension circular summarizes some of the biology and ecology of these predators and emphasizes the benefits they can provide in pest control. Producers are encouraged to use selective insecticides for controlling pests if insecticides are required. This will conserve important predators like assassin bugs and many other beneficial species.