- 18 - 
in cornfields were velvetbeans or peanuts. The high average population 
for cornfields was due to heavy growth of cockleburs in early corn. 
The smaller larval population in the fall of 1938 was due to several 
factors, namely, the retirement from crops and the maintenance of a fallow 
during 1938 in practically all the heavily infested fields in the Florala 
area, the scant rainfall after August 8, and probably others not known at 
the present time. 
Larval m ort ality. — The mortality of larvae from the fall of 1937 to 
June 1938 was great. The decrease in larval population, as shown by the 
soil samples from 41 fields in the Florala area from November-December 
1937 to June 6-7, 1938, was 88.8 percent. In one field which received 
normal farm practices the larval population was determined on November 1, 
1937, and March 1 and June 1, 1938. The adult emergence was also determined 
in this field. The larval population on November 1, 1937, was 301.2 per 
square yard. The population had decreased to 167.4 per square yard on 
March 1 and to 68 per square yard on June 1, 1938. The larval population 
had decreased 44.4 percent by March 1 and 77.4 percent by June 1. The 
exact cause of this high mortality has not been definitely determined, 
although the larvae bite one another when they come into contact, thus 
causing some of it. The adult emergence in the field was 23.5 per square 
yard, or 7.8 percent of the November larval population. The larval popula- 
tion in this field in November 1938 was 390.7 per square yard. 
C ons truction of the pupal cell . — After the larvae have completed 
their growth and stopped feeding they retire from immediate contact with 
plant roots and construct pupal cells in the soil. The cell is made by 
movements of the larva which gradually pack the soil until a smooth cavity of 
sufficient size for the activities of pupation and emergence is formed and 
glazed with a secretion from the insect's body. Although these cells are 
practically waterproof, moisture must penetrate them slowly to a certain 
degree, since the adults within cells react to outside moisture conditions. 
The longitudinal axis of the pupal chamber is on an inclined plane. 
The p repupa . — The average length of the prepupal period as determined 
from 9 specimens was 11.2 days; the periods ranged from 9 to 15 days. In 
this stage the insect is semi-inactive, and the body becomes somewhat 
straightened, losing its former much-curved shape. 
The pupa 
The pupa (fig. 1, E) is approximately seven-sixteenths inch in length, 
and when first formed is white. Parts of the body and appendages darken 
somewhat before transformation. 
The average length of the pupal period for 135 specimens was 12.5 
days; the periods ranged from 8 to 15 days. 
The average depth of pupation as determined in 1938 was 3.8 inches. 
An average of 93.7 percent of the pupae were found from 2 to 6 inches below 
