THE CONCHUELA. 67 



destroyed by some enemy rather than of having died from natural 

 causes. As has been shown, the decrease in number is a general and 

 not a local occurrence, and it takes place without regard to the 

 abundance of food. These circumstances seem to point to the strong 

 probability that birds are the useful agents in the reduction of the 

 numbers of the adults of the conchuela. 



ARTIFICIAL CONTROL. 



Under the heading, ''Artificial control," will be discussed only 

 those measures w^hich have little or no application except for the 

 conchuela, together with such measures as have been the object of 

 especial observation during the observation of that pest. 



PREVENTIVE MEASURES. 



Clearing land of mesquite. — As a means of obviating in a large 

 measure the destruction by the conchuela, the prevention of spring 

 multiplication of the pest on mesquite in the vicinity of cotton fields 

 is of prime importance. Near Llano, Tex., Mr. J. C. Crawford, of 

 this Bureau, on September 3, 1905, found an excellent example of 

 the conditions which may result from the neglect of a breeding place 

 of plant-bugs. As would be expected from its previous history else- 

 where, the conchuela was in comparatively small numbers at that 

 season of the year, but associated with it were two other plant-bugs, 

 which will be treated later, Largus succinctus L. and Nezara Mlaris 

 Say. These three pests were breeding on a group of about 4 or 5 mes- 

 quite, located just outside of the cotton field. In the cotton field 

 the damage to the bolls and the abundance of the plant-bugs in the 

 section close to the mesquite, as compared with other parts of the 

 field, gave almost conclusive evidence that the presence of the trees 

 mentioned was largely or entirely responsible for the conditions 

 found. In this and similar cases, therefore, the removal of the mes- 

 quite w^ould unquestionably result in considerable benefit to the 

 cotton, repaying the trifling cost many times over in a single season. 



Under conditions such as those at Tlahualilo, where the cotton 

 and surrounding mesquite land are under the same management or 

 ownership, the policy should be adopted of removing, as fast as 

 practicable, the mesquite, which experience has shown to be an ele- 

 ment of danger. Where farms are comparatively small and a 

 diversity of crops is grown, as at Barstow, Tex., the results might 

 not be as striking as elsewhere, but concerted effort among land- 

 owners toward the eradication of mesquite growing in and around 

 cultivated lands is recommended. 



Prevention of excessive multiplication on alfalfa and other plants. — 

 In addition to mesquite, alfalfa is the only other food plant which 

 has thus far shown itself likely to harbor the conchuela in numbers 



