STUDIES OF THE PINK BOLLWORM IN MEXICO 39 
plat and 16 in the plat that was plowed only. However, some later 
examinations show up entirely differently. Thirteen living speci- 
mens were found in a square yard from plat 2 on April 17, and the 
same number in a square yard from plat 3 on May 1. It is evident 
that further experiments should be conducted. 
In addition to the soil examination, three cages were placed on 
each plat (except plat 5) to catch any emerging moths. Each cage 
covered 1 square yard and had a trap arranged in the middle to 
catch emerging moths. Paper covers were placed on the cages at 
night, leaving only the traps exposed. It was thought that moths 
seeking light or free air would more readily enter the traps in this 
way. The cages were examined every second or third day with the 
following total results: 
Plat 1. 2 moths, April 15. 
2. 1 moth, April 15. 
3. moth. 
4. 1 moth, April 30. 
In August all these cages were removed and the surface of the soil 
under each one carefully examined for signs of any moths that might 
have emerged and not entered the traps. Only the following were 
found : 
Plat 1. 1 dead pupa in cocoon on surface of ground, 1 pupal case under base 
of cage. 
2. 1 pupal case under clod of earth. 
3. 1 pupal case under clod of earth. 
4. 1 pupal case under clod of earth. 
The efficiency of the traps on the cages was tested. One cage was 
set up as it had been in the field, 20 moths were placed under it in 
the afternoon, and the paper cover was put on during the night. 
Only 6 of the 20 moths were found in the trap on the morning fol- 
lowing. This .indicates that probably only 30 per cent of the moths 
that emerged under the cages in the field were caught in the traps. 
One striking point brought out is the difference between the 
number of moths that emerged and the number of living larvae found 
in the soil. Table 29 gives an average for the first two examinations 
in plat 1 of 14 living larvae per square yard. On this plat, in 2 cages, 
covering a total area of 3 square yards, only 2 moths were caught. 
If this was 30 per cent of the moths that actually emerged under the 
cages, there was a total of 6.67 moths, or an average of about 2.2 
moths, emerging per square yard. 
EMERGENCE OF ADULTS THROUGH SOIL 
An experiment was conducted in the spring of 1922 to determine 
the depth of soil through which a moth can emerge. Two sets of 
sheet-iron cylinders were made. These were 5 inches in diameter 
and closed at the bottom and ranged in depth from 4 to 20 inches. 
Larvae in cocoons from the soil and in cottonseeds were placed in 
the bottoms of the cylinders and covered with soil to different depths 
(see Table 30). The cylinders were taken to the field and sunk in 
an upright position in the ground so as to leave the surface of the 
soil in the cylinder on a level with the surface of the soil on the out- 
side. Screen-wire traps were made to fit the tops of the cylinders, 
so that any emerging moths might be caught. 
