Arrticte 1.—The North American Species of the Genus Tiphia 
(Hymenoptera, Aculeata) in the Collection of the Illinois State Natural 
History Survey. By J. R. MAttocu. 
‘ INTRODUCTION 
In the course of the work upon white-grubs (Phyllophaga spp.) 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 collec- 
tions 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, | 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 pos- 
sible 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. 
I endeavored by dissection of the males to use the structure of the 
hypopygium as a check upon my separation of specimens by external 
characters such as punctuation, venation, and the shape of various parts 
of the body; but the hypopygia of closely related species, or at least of 
_forms that appeared to me to be such, resemble each other so closely 
that I found very little assistance could be obtained from a study of 
these. 
I also arrived at the decision that the punctuation of the various 
parts of the body, while fairly constant and very useful for specific 
separation, is subject to variation, small specimens of such species as 
imornata Say usually being almost devoid of the minute interspersed 
punctures which are characteristic of normal-sized specimens. These 
small specimens are probably the result of starving in the larval stage—a 
condition frequently found in predaceous and parasitic forms. 
One of the most important characters that I discovered in the genus 
is a longitudinal groove on the inner or posterior surface of the basal 
joint of the hind tarsi of the females in the section to which punctata 
