32 BULLETIN 19, U. S. DEPARTMENT OF AGRICULTURE. 
longevity of overwintering adults, number of eggs deposited per 
female, length of nymphal stages, etc., were covered with a cage 
early in the season so as to prevent the foliage from becoming 
infested by other adults. 
Since it was impossible to secure enough Riley cages, or to have 
cages made that were sufficiently tight to prevent the escape of the 
adults, recourse was taken to the use of a number of second-hand 
arc-light globes, which were secured from the local lighting plant. 
These were about 15 inches high, with a small opening about 4 inches 
in diameter and a large opening about 8 inches in diameter. The 
globe was placed over the vine with the lower opening resting on the 
ground, and the larger opening was covered with a piece of muslin 
fastened to a stout wire ring. This cover was drawn tightly over the 
large opening by means of four cords fastened to the wire ring and 
connected to four pegs driven into the ground and tightened in the 
same manner as are the cords of a tent. In this way it was possible 
to draw the muslin perfectly tight all around the edge of the upper 
opening of the globe. The insects were examined during the cooler 
part of the day when they were least active. It was found that when 
the lower opening was set into the ground, the temperature inside of 
the cage was several degrees higher than that on the outside, owing 
to a lack of circulation of air inside the cage. This was overcome by 
taking a strip of fine wire screen about 4 inches wide and forming 
it into a collar a little larger than the smaller opening of the globe. 
This collar was then slipped over the young grapevine and pressed 
firmly into the soil. The globe was then placed over the vine and 
the small opening fitted into the wire screen collar, thus securing an 
air current into the bottom of the cage up through the muslin cover 
or vice versa. The muslin cover was then made large enough to 
shade the greater part of the globe. These modifications resulted in 
securing a cage that was light and tight, and that had a temperature 
about the same as that on the outside. 
The cage that has just been described (see PL II, Rg. 1) is spoken 
of as an "arc-light globe cage" in connection with the rearing experi- 
ments mentioned under seasonal history. 
A smaller cage, employed for rearing single nymphs for the purpose 
of recording the length of the stages of individuals, is fully described 
on page 26 under another caption dealing with experiments to deter- 
mine the length of the nymphal stages. 
PARASITES AND PREDACEOUS ENEMIES. 
Apparently the grape leafhopper suffers little from the attack of 
parasitic enemies. No records of parasites have been found in the 
literature dealing with this pest. During the investigations on grape 
insect pests conducted at North East, Pa., from 1907 to 1912, only 
