December, '21] morrill: thurberia boll weevil 473 



variety of the boll weeviP has been repeatedly pointed out in various 

 publications following the early investigations of the problem, principally 

 by Dr. W. D. Pierce and the writer in IQIS^ and Mr. B. R. Coad in 1914. 

 The possibility that the Thurberia weevil might not be able to adapt 

 itself to lower elevations than its known habitat in the moimtains of 

 Southern Arizona provided a basis for a certain amount of optimism 

 but the seemingly well grounded hope that the insect might be restricted 

 in its future distribution by the factor of elevation was dissipated in 1916 

 by the discovery of the Thurberia weevil at sea level in Sonora, Mexico, 

 by Mr. E. A. McGregor. A maximum longevity record of 626 days for 

 the Thurberia weevil brought to my attention by Dr. Pierce in cor- 

 respondence has further emphasized the peculiar status of the insect as a 

 potential pest of cultivated cotton. Fortunately, under natural con- 

 ditions, the relation of the food supply to the weevil in the native 

 habitat of the latter has been such that as long as the "status quo" 

 of the insect and its native food plant was undisturbed, the danger of 

 infestation of cultivated cotton in the valleys was practically limited to 

 water transportation by means of floods from the mountains. The 

 ill advised disturbance of thi ^, generally satisfactory relation by an erad- 

 ication cam.paign directed against the plant rather than its insect 

 enemies, even followed as it was by a season of unusually light rainfall 

 and absence of floods reaching into the valley's, made infestation of 

 cultivated cotton by flight of the insects, practically inevitable. The 

 discover}' of the weevil infestation in cotton fields in October 1920, bore 

 out a prediction made with the utmost confidence by the writer after an 

 investigation of the situation several months earlier. 



While the Thurberia boll weevil has been generally considered the most 

 noteworthy of the pests of the Thurberia plant, the potential importance 

 of the Thurberia bollworm^ has never been questioned and it is obvious 

 that the existence of the latter in the same localities as the weevil, intro- 

 duces a complicated problem which must be taken into consideration in 

 any intelligently planned attempt to eradicate the weevil and its host 

 plant in any area. It is of interest as a side light on the situation that, 

 according to a statement made to the writer by Dr. C. T. Vorhies of the 

 University of Arizona, the Thurberia bollworm was not discussed or 

 considered in connection with the planning of the eradication campaign 

 which was done at a conference he attended early in October, 1919. 



The rapid development of the cotton industry in the Southwest 

 having made de.-?irable a reconsideration of the wild cotton problem 



'Anthonomus grandis Boh. 



-Pierce and Morrill. Proc. Ent. Soc. Wash, vol xvi, pp 17-19, 1914. 

 'Moirill, Fifth Annual Rept. Ariz Comm. Agi . and Hort. p 47, 1914. 

 Morrill, Jour Econ. Ent. vol. x p312, 1917 



