Phenological Relationships of Wasps, Bumblebees, Their Mimics, and Insectivorous Birds In an Illinois Sand Area

Abstract

Surveys in a xerophytic forests association in an Illinois sand area showed that specialized Batesian mimics of stinging bumblebees or wasps are numerous in spring and early summer, generally absent in midsummer, and present but infrequent in late summer. This extends the known occurrence of this sort of seasonal distribution among mimics to a group of mimetic species which are rare or do not occur in the mesophytic forest associations in Illinois which were surveyed by two previous investigators. Our findings support the hypothesis of these previous investigators that some temperate zone Batesian mimics may be selected to avoid the midsummer season when newly fledged, insectivorous birds are abundant and have not yet learned to shun the models which the mimics resemble.