The species in the genus Pompilus Fabr., judging from the records, seem to have a diversity of habits. According to Westwood, Pompilus niger Fahr. in England provisions its cells with small Lepidopterous larvae; Pompilus fumipennis Zett. with ants, while Pompilus petiolatus preys upon spiders. Now no doubt this diversity of habits will be found correlated by structural differences, which should be used in separating this extensive genus into subgenera. In our fauna, most of our species in this genus, or at least those whose habits are known, feed upon spiders.
Ashmead, William H., "The Habits of the Aculeate Hymenoptera. IV" (1894). An. Paper 60.