The natural history of the interesting gall insects is still somewhat mysterious. A large number of observations have been made here and in Europe by prominent Entomologists; nevertheless, a careful study of the most detailed papers always gives the impression that something is still wanting to explain the various facts related by the authors. Among the Hymenopterous gall insects important progress was made in the discovery by the late B. Walsh of the dimorphism of C. q. spongifica and C. q. aciculata, the latter one a parthenogenetic species. But even here new observations are wanted to fill some gaps in the history of those species. Mr. W. F. Bassett, of Waterbury, Conn., draws my attention to the fact that in a letter in the Proc. Entom. Soc. Lond., April, 1873, p. xv., he “did state most emphatically his belief that all one-gendered gall flies were the alternate of a two-gendered brood from galls of a different form,”