In this chapter, we consider practical aspects of the foraging behaviour of insect natural enemies in its widest sense (so wide that we even include a few examples concerning non-insect arthopods, such as mites). Initially, most insect natural enemies must locate the habitat where potential victims may be found. Within that habitat, the victims themselves must be discovered. Once a patch of potential targets is identified, the predator or female parasitoid must choose its victim. Furthermore, in judging host quality, a female parasitoid must decide whether to feed from the host, to oviposit, or to do both. If she does decide to oviposit, then there are questions of sex allocation and offspring number that need to be addressed (Fig. 1.1). All of these activities fall under the aegis of ‘foraging behaviour’.