Behavior of Phytophaga destructor Say 569 
FIRST TRIAL, NASHVILLE, ILL., APRIL 10 TO 30,1917 
The cages just described were arranged in a row extending east and 
west. Each covered 1 square yard of heavily infested winter wheat. 
There was reason to believe that each square yard was as nearly uni¬ 
formly infested as was possible to obtain. However, there is some 
question as to whether an approximately equal number of flies might 
be expected to emerge in each cage. The cages were set in position 
April 9. During the 21 days of the experiment the total number of 
flies taken from each cage was as follows : A, 65; B, 63; C, 8; D, 134; 
E, 54; F, 61; total for all six cages, 385. 
Fig. 2 —A, emergence cage for the Hessian fly, type E, having A-shaped frame of cypress, covered 
with 18-mesh screen wire; B , emergence cages in place for outdoor experiment; C, 12,000 “flaxseeds 
or puparia used in indoor experiment; D , emergence cage, type F, having A-shaped frame of cypress 
covered with 18-mesh screen wire, except door, which is 12-mesh 
The results obtained indicate that cage D was approximately twice as 
efficient in recovering flies as the best of the other cages. Cage C shows 
up very poorly, whereas the other cages are so close together in num¬ 
ber of flies recovered that other considerations might be allowed to in¬ 
fluence the selection of one of these cages for any particular purpose. 
A comparison of temperature, evaporation, and rainfall in each cage 
with that of natural conditions outside, or normal, was made. Tem¬ 
perature variations were determined by radiation thermometers placed 
close to the soil surface, and are shown in degrees plus or minus from 
the normal. Variations in evaporation were determined by compen¬ 
sating atmometers, and are shown in cubic centimeters plus or minus 
from the normal; the evaporation for each preceding 24 hours being 
recorded at 8 a. m. Variations in rainfall were determined by espe- 
