General properties of crop colonization by herbivores and their predators and parasites are discussed using soybeans as an example and the theory of island biogeography as a conceptual basis. Crop development is described and contrasted to typical island situations. In the crop, resources for herbivores are sufficient, but for predators and parasites they are deficient. This difference was seen in the colonization curves for the 2 groups. There was a lag between colonization by herbivores and their enemies with no appreciable increase in the latter until the soybean canopy was developed. Colonization and extinction rates were higher at the field edge than in the center, but an equilibrium number of species did not develop at either site in time to be of predictive value in developing pest management strategies. Methods for counteracting the destabilizing influences of current agricultural practices on arthropod communities are discussed.