Rhamphomyia mutabilis, Loew., has several times been observed preying upon Bibio pallipes, Say. I once saw hundreds of the former on a picket fence that had recently been whitewashed, and all appeared engaged in capturing the latter; at any rate hardly one could be found that was not engaged in sucking the life out of a victim. In one case the sexes were pairing while the female was lunching upon a recently captured Bibio.