2 
Robertson belongs. This groove is absent in the females of inornata Say 
and its close allies and also in the males of all species that I have exam- 
ined, so that it can not be used as a subgeneric character, more especially. 
as the males of the two groups are not separable from the punctata group, 
as far as I can discover, by any character or set of characters that is 
found in all of these species. What the function of this groove is I can 
not determine; it may not have any particular function, but the apical 
spur on the posterior side of the hind tibia is so placed that it can fit into 
the groove and may form, or have formed at one time in the evolution o 
the group, a stridulatory organ. Stridulatory organs in the Hymenoptera 
are normally found on the thorax and abdomen, and in other groups on 
the wings, abdomen, thorax, and legs. That the tarsal groove above 
mentioned may have some function altogether different from the one sug- 
gested here is quite possible. 
The peculiar curved horn-like process at the apex of the abdomen in 
the males of Tiphiinae is the eighth ventral abdominal segment and not 
part of the hypopygium. 
The females of at least the larger species can sting a person’s hands, 
as I know from experience, but I have handled dozens of females of the 
smaller species without being stung by them. 
In collecting specimens during 1917 particular attention was paid to 
localities in which no previous effort had been made to obtain a represen- 
tative series of this group, with the result that considerable numbers of 
species were found that were not previously represented in our collection. 
At Dubois, in the southern part of the state, many examples of several 
small species were taken by sweeping black-jack oak; and later in the 
year some of the same species were found under the same conditions at 
Havana and at Meredosia. 
It is not to be assumed that the Tiphia species discussed in this 
paper constitute an exhaustive list of those occurring in Illinois, and it 
is certain that a very large number of those occurring in the United 
States are unknown to me; but the present paper contains the most com- 
prehensive survey of the North American species yet attempted, contains 
many new characters for the differentiation of the species, and should 
prove useful to students of the group. 
Hapits or SPECIES 
So far as is known the larvae of Tiphiae are ectoparasitic upon 
coleopterous larvae. The habits of several species described in this article 
are discussed in another article in this volume, by Mr. J. J. Davis. 
The species particularly affecting white-grubs in cultivated lands are 
absent from the sand regions near Havana and Meredosia, Illinois, the 
common species in these localities being much smaller than those that 
attack white-grubs. They probably feed upon larvae of Scarabaeidae 
occurring in the groves of black-jack oak, which are characteristic of 
these regions. It is noteworthy that at Dubois I found some of the small 
