148 



hope that any parasite will ever become an efficient factor in controlling 

 this dangerous pest. 



There is at present, therefore, no promise of any considerable 

 assistance in the control of the weevil by any parasite now known. 

 Because of its peculiar life history the weevil is unusually exempt 

 from the attacks of parasites. Even should one be found which 

 could attack the weevil in some stage, it would probably still fail to 

 be an efficient means of control, because, from the very nature of its 

 parasitic habits, it is bound to be behind the weevil both in the point 

 of numbers and in the time of its activity. While such parasites 

 might serve to decrease the numbers of the weevil, every larva that 

 becomes parasitized has already done its damage to a square. 



In spite of the present unpromising outlook for the discovery of 

 valuable parasites of the weevil, every effort to find such should be 

 made. While earnestly hoping that effective parasites may yet be 

 discovered or developed, it is folly for planters to neglect or delay the 

 adoption of those methods of decreasing weevil injury which have 

 already proven to be both practical and effective. 



PKEDATORY ENEMIES, 



INSECTS. 



NATIVE ANTS. 



Insects which prey upon the boll weevil appear to be even fewer in 

 number of species than are those which are parasitic upon it. The 

 principal enemies of this class are ants, and where common these prob- 

 ably destroy more immature weevils than do the parasites. The first 

 attempt to make practical use of ants in controlling the boll weevil 

 was made by Mr. A. F. Rangel, who is connected with the Comision 

 de Parasitology Agricola of the Mexican Government. In 1901 this 

 investigator was informed by Mr. D. Juan Jose Rodriguez, who 

 resides in the vicinity of Ciudad Porfirio Diaz, in the northern portion 

 of Mexico, that an ant which prevented the development of the boll 

 weevil had been discovered in that vicinity. It was thought at the 

 time that as colonies of ants may be easily transported from place to 

 place it might be possible to make extensive use of them. The field 

 which seemed to have been protected by the ants had an area of several 

 acres. 



A number of colonies of this ant, which was determined by Prof. 

 W. M. Wheeler 2,% Formica fusca subj^olita perjoilosa^ were transported 

 a distance of some miles to San Carlos, where an attempt was made to 

 establish them in cotton fields. It was found a comparatively simple 

 matter to transport the ants in a device very similar to that subse- 

 quentl}^ used by Mr. O. F. Cook in the introduction of Ectatomma 

 tuherculatum. Although the introduction of the ants to the cotton 



