Chaoborus larvae are important planktonic predators in lakes.  I studied prey capture by fourth-instar C. americanus, C. flavicans, and C. punctipennis larvae feeding on the cladocerans Scapholeberis and Daphnia.  I observed larvae feeding on prey of various sizes and recorded strikes, captures, ingestions, and handling times.  Capture efficiencies were higher than strike efficiencies in all experiments.  In almost every case, higher capture and strike efficiencies were correlated with larger Chaoborus larvae.  Head capsule length and width were significantly different among the three Chaoborus species (C. americanus > C. flavicans > C. punctipennis).  All of the prey size classes were significantly different in both length and width, with the exception of the similar widths of Scapholeberis 350-500 µm and Daphnia 250-350 µm.  In general, as prey size increased, capture and strike efficiencies decreased.  My results suggest that while Chaoborus larvae have no difficulty ingesting prey with lengths greater than their mouth gape, predation is strongly inhibited when prey width is similar to mouth gape.  Understanding these aspects of Chaoborus prey capture may aid in explaining the effect of Chaoborus species composition on the size and structure of zooplankton communities.