38 INSECT ENEMIES OF THE BOLL WEEVIL. 



Texas and in all of Oklahoma. At the same tune a maximum infesta- 

 tion was found in all of that part of Louisiana lying south of the Red 

 River and in Mississippi for about 20 miles east of Natchez. An analy- 

 sis of the parasite records for this same season shows that the parasite 

 control of the weevil in these sparsely infested regions of Texas was 

 very light, whereas the control in the heavily infested regions of south- 

 ern Louisiana and ^Mississippi was correspondingly very high. The 

 inference drawn from this observation is either that the boll weevil 

 had ceased to be the predominating weevil species for parasitic 

 attack in the lightly infested region, or that the parasites had been 

 destroyed by the heat. That the parasites were not all destroyed 

 by the heat is demonstrated by many records of the same parasites 

 on other species of weevils during the fall and wdnter of 1909. 



10. A BEIEF STATEMENT OF THE VARIOUS CLASSES OF CONTROL EXER- 



CISED UPON THE BOLL WEEVIL. 



Before passing from this part of the report, which deals with the 

 general conditions obtaining, it is necessary to say a few words con- 

 cerning the classes of control which are of importance in repressing the 

 boll weevil. The first agency which is responsible for mortality of the 

 weevils is the resistance of the cotton plant to attack, evidenced either 

 by the toughness of the plant tissues which must be punctured, or by 

 the proliferation of the tissues, which destroys the weevil eggs and 

 larvae by crushing. When the infested form falls to the ground or 

 withers on the plant it becomes immediately a subject for numerous 

 other factors of control. Intense heat kills many stages. A large 

 number of parasite species seek out infested squares for their prog- 

 eny; myriads of ants, beetles, and mites find nourishing food by 

 merely cutting their wa}^ into the infested forms and devouring the 

 weevil stages. Li addition to these, sudden cold freezes countless 

 numbers of developing weevils. Neither are adults free from adverse 

 conditions. Man}^ are killed by heat, or cold, or dro^vning; many are 

 picked up by birds and lizards or preyed upon by other insects ; and 

 finally multitudes are starved on account of the ravages of other 

 insects upon their food supply. In this report we are able to deal 

 only with the three factors which are determinable in the control of 

 immature weevils, namely, climate, parasites, and predators. 



11. PRACTICAL CONCLUSIONS DERIVED FROM STATISTICAL STUDIES. 



The following conclusions of economic importance have been 

 reached from a study of this large series of statistics : 



I. The month of August is the most important month for the con- 

 trol of the weevil by insect enemies. As this month is also the most 



