CONTKOL BY WINTER CLIMATIC CONDITIONS. 19 



the spring, every plant of it should be destroyed to prevent its nourish- 

 ing the weevils which may have survived. The practice of allowing 

 sprout cotton to grow in a field of planted cotton can not be too 

 strongly condemned. Certainly if planters could appreciate the fact 

 that these occasional plants will, under usual conditions, enable the 

 weevils to do much greater injury to the main crop, they would be very 

 careful to destroy them. If planters in southern Texas fully appre- 

 ciated the importance of this menace, there would soon be developed 

 a strong public sentiment which would compel every planter to adopt 

 methods which would prevent the occurrence of sprout cotton. It 

 is entirely possible in a great majority of cases for the planter to 

 insure for himself the beneficial effect of a large reduction in the 

 number of weevils surviving hibernation, such as would result from 

 occasional winters of unusual severity, even during seasons which 

 would be favorable for the survival of large numbers of weevils. 

 This, then, is the part of cultural practice which may be made to 

 regularly supplement or possibly supplant the beneficial effects 

 which are occasionally experienced by an exceptionally large degree 

 of natural control through severe climatic conditions during the 

 winter. 



RELATIONSHIP OF FACTORS OF CONTROL. 



It is evident that these factors, which are but the extreme fluc- 

 tuations in climatic conditions, will only occasionally exert their 

 maximum effect, and that under normal conditions of temperature 

 and humidity other factors, having a more constant average effi- 

 ciency, may surpass climatic variations in their controlling effect 

 upon the weevil. It is to a study of some of these average factors 

 that the present paper will be mainly devoted. Among the factors 

 concerned in the natural control of the boll weevil in the United States 

 to which especial attention has been given may be mentioned heat 

 or drying, native ants, proliferation, parasites, the limitation of the 

 weevil's food supply by the work of the cotton leaf-worm (Alabama 

 argillacea Hbn.), and birds. 



In this bulletin special consideration will be given to the effects of 

 heat or drying, native ants, and parasites. Proliferation was 



a "Proliferation," as the term is used in connection with cotton, refers to a phe- 

 nomenon which frequently follows the attack of weevils or other insects in cotton 

 squares and bolls. It may be defined as the development of numerous elementary 

 cells from parts of the bud or boll which are themselves normally the ultimate prod- 

 ucts of combinations of much more highly specialized cells. The resulting product is 

 thus composed of comparatively large, thin-walled cells, which are placed so loosely 

 together that the formation is of soft texture and has a granular appearance which 

 may be seen with the naked eye. Proliferous formations lack the distinctive texture 

 which is characteristic of the normal parts of either bud or boll. The consistency of 

 the formation is soft and yielding, resembling somewhat a rather soft gelatin. From 

 this apparent resemblance the term "gelatinization" is sometimes used instead of 

 proliferation. 



