No species seems to be known in this family outside of the European and North American faunas, and very few species are described. The group was first treated as a subfamily by Newman as early as 1834.

The imagoes appear very early in the year, or in February, March and April, deposit their eggs and then disappear, the consequence being that very few are taken and only a few of the commoner forms are known. With more careful collecting early in the season, however, the probabilities are that many more species will be discovered in our fauna.

The imagoes of three distinct species of these insect, representing as many genera, have been bred recently from the larvæ by Dr. H. G. Dyar, and we are not only indebted to him for the first authentic life-history of a species in this group, but also for the first scientific description of the larva. His recent discovery of a large undescribed species in the rare genus Pleuroneura was most unexpected.