Field Studies of the Non-Social Wasps 341 
men of C. bicornuta. In 1917 I was out of the city, and 
the next summer, on June 30, the first specimen was cap- 
tured; during the following week six others were found 
nesting there. This shows how quickly and firmly they 
become established when they find a desirable environ- 
ment. 
C. bicornuta preys upon three species of bill-bugs, 
Sphenophorus placidus, S. zeae and S. parvulus. Bill- 
bugs are very destructive to cereal and forage crops, and 
the Cerceris wasps are one of the important natural 
checks. The blue-green bill-bug, 8. parvulus, is a widely 
distributed upland species usually infesting timothy and 
bluegrass, but often injuring wheat, oats, barley and rye. 
Pupation occurs either in the corms or in the soil. 
A large blue cuckoo-bee, Hedychrum violacewm, en- 
tered the burrow of this wasp and remained within for 
twenty minutes; what her errand was we can only sur- 
mise, 
Adults of this species have been found feeding on the 
flowers of the buckbrush. 
