However, these wasps feed the larvae in their nests with animal material, including insect prey. Some studies have shown that there is a correlation between the number of wasps in an area and the number of certain types of caterpillars. Research at the University of Wisconsin has shown that increasing the numbers of colonies by providing suitable nesting sites resulted in a decrease in the number of the cabbageworm complex. Individual females provision individual cells, each of which contains a single larva. Some use spiders , and one uses exclusively the black widow spider .
Ants are amongst the most numerous of all types of animals, and many species are predaceous.
Because of their abundance, they can have a significant impact on the populations of other insects, including pest species. Some of the earliest records of biological control, going back many centuries, involve the use of ant colonies in date and citrus orchards for controlling a variety of pests. More recently, studies in the southern United States have shown that fire ants are very important in controlling certain types of agricultural pests. It should be noted however, that fire ants also consume other beneficial insects.