In the course of the work upon white-grubs by various members of the staff of the Illinois State Entomologist's office many specimens of the parasitic hymenopterous genus Tiphia have been obtained either by rearing from the larvae or pupae or in general collections of imagines. About two years ago I undertook to work up this mass of material with a view to determining how many species there are affecting white-grubs in Illinois and also to determine, in so far as our material permits, the distribution of the various species. At the outset of my work I encountered great difficulties to progress, chief of which was the extremely unsatisfactory nature of the descriptions of most of the previously described forms. Coupled with this is the fact that the species are remarkably closely related, presenting but few characters that are appreciable except after considerable study. After several months of intermittent study of our material, I was forced to the conclusion that it was necessary for me to obtain specimens from more diverse localities in order to enable me to determine satisfactorily whether certain trivial characters possessed a specific significance; consequently on every possible occasion during my field work in 1917, I collected specimens of Tiphia, and I also borrowed a large number of specimens from Mr. Nathan Banks, the latter containing examples from many states in the Union.published or submitted for publicationis peer reviewe
