Family V. MELLINIDAE. This family (if we can call it a family) is represented in our fauna by one genus with three species, and as these are exceedingly rare, no observations on any of them have been made. Westwood, however, has observed the European Mellinus arvensis burrowing in sand-banks, and Shuckard states the species preys upon Diptera. Kirby and Spence also say it selects the smaller flies, including the troublesome Stomoxys calcitrans.
Ashmead, William H., "The Habits of the Aculeate Hymenoptera. III" (1894). An. Paper 59.