32 
It will be noted that the acreage in peas, as compared with the acre- 
age in cotton, decreases almost in proportion to the increase in sever- 
ity of bollworm injury in the respective States. In Texas, where 
there is but 1 acre in peas to every 205 acres in cotton, bollworm 
injuries are of greatest severity. 
The very general practice of planting late corn for forage, silage, 
and other purposes is, in effect, the application of the trap-crop idea. 
By this practice, which has come about simply as a farm expedient, 
the farmers of the Carolinas, Georgia, and portions of Alabama have 
unconscioush" greatly lessened the danger of bollworm injurv to cot- 
ton by providing the insect with a succession of its favorite food plant. 
RELATION OF WEATHER TO BOLLWORM INJURY. 
The belief is firmly established in the minds of many cotton planters 
that rain}^ weather, especially during late July and earh^ August, is 
largeh^ responsible for severe bollworm injury to cotton. Further, 
the opinion is occasionally expressed that the "'worm" is the direct 
result of such weather conditions. The fact that it is just at this time 
that the hardening of field corn forces the moths to the cotton fields 
appears to be lost sight of, and the sudden and destructive appearance 
of the larvae on cotton has often been attributed to the occasional 
showers Avhich may occur at this time of year. However, a belief so 
well established, resulting from many years of observation and expe- 
rience, should have some foundation in fact, and such appears to be 
the case. The accurate explanation of the factors involved, however, 
is by no means easy, owing to the difficulty of obtaining data on a 
question of this kind. 
As the reader will learn in the following pages of this bulletin, the 
bollworms, upon completing, during July, their growth in the ears of 
field corn, enter the soil and, after constructing a cell, become pup^e, 
from which, in_the normal course of events, the moths or parent insects 
issue about two weeks later. Observations have shown that many 
of these pupal cells are not made with sufficient care b}^ the larvae 
to permit of the ready escape of the moth from the soil. The most 
common defect is that the cell is not extended upward sufficienth^ 
near the surface of the ground so that there will be but a thin crust of 
earth for the moth to break through in making its escape. The occur- 
rence of a soaking rain and the consequent softening of the soil would 
permit the escape in perfect condition of many moths which under 
conditions of hard-baked soil must have perished in their pupal bur- 
rows. It has often beeii observed in the course of this investigation 
that moths were noticeably more al^undant shorth^ after a soaking 
rain. This fact probably has its explanation, as above intimated, in 
