6 CONTROL OF THE BOLL WEEVIL. 
measures and to increase the effectiveness of the several natural 
factors which serve to reduce the number of weevils. Thus the 
control measures constitute a combination of expedients, the parts of 
which interact inmany ways. Naturally, the best results are obtained 
when the planter can put into practice all of the essential parts of 
the combination. 
It is obvious that any method of controlling the boll weevil must 
depend upon full knowledge regarding its life history and the natural 
forces which tend to prevent its multiplication. Gertain practices 
which upon superficial observation might be considered important 
in the control of the insect, upon investigation may be found to be 
of no avail whatever. In fact, in some cases what appear to be 
feasible means of control are worse than useless, because they tend 
to nullify the effects of natural forces which act against the weevil. 
This is notably the case with the practice of attaching a bar to a 
cultivator to jar the infested squares from the plants. As will be 
explained later, this practice is of advantage under only very restricted 
conditions. Throughout the greater part of the infested territory 
it is an assistance rather than a hindrance to the boll weevil. 
There are seven features of the life history of the weevil that are 
of cardinal importance in control. These are indicated below. 
(1) The weevil has no food plant but cotton. 
(2) The mortality of the weevil during the winter is very high. 
(3) The emergence from hibernating quarters during the spring is slow and prolonged 
until well into the summer. 
(4) Early in the season, on account of comparatively low temperatures, the develop- 
ment of the weevil is much slower than during the summer months. 
(5) The drying of the infested squares soon destroys the immature stages of the 
weevil contained therein. 
(6) The weevil is attacked by many different species of insect enemies, the effec- 
tiveness of which is increased by certain practices. 
(7) The weevil has but little ability to emerge when buried under wet soil. 
Exactly how each of these features of the life history of the weevil 
affects plans for practical control will be explained in the following 
paragraphs: 
In the case of many of the important injurious insects the problem 
of control is greatly complicated by the fact that the pests can sub- 
sist upon more than one food plant. In some cases a single species 
attacks several cultivated crops. In other cases the pests can subsist 
upon native plants practically as well as upon the cultivated species. 
All these difficulties are absent in the case of the boll-weevil problem. 
The insect is absolutely restricted to the cotton plant for food and for 
opportunities for breeding. The problem, therefore, is much more 
simple than it would be if the weevil could subsist upon any other 
plant in the absence of cotton. This peculiarity of the weevil (. e., 
500 
