June, '13] TOWNSEND: COTTON SQUARE WEEVIL 307 



In the San Bartolome to ^Nlatucana districts and others just a little 

 farther back into the foothill region from Chosica and higher up, 

 where the warm season changes to humid while the cool season re- 

 mains arid, the weevil should be decidedly active from December 

 to May, much more so than at Chosica. Matucana is 7,800 feet al- 

 titude, yet its temperature during July, 1912, ranged from 45° to 77° 

 Fahrenheit, or 7° to 25° Centigrade. Its nights are therefore practi- 

 cally the same during the cool season as those at Chosica and lea, 

 while its days at the same season are slightly warmer than the lea 

 days and slightly cooler than the Chosica days. So far as the climate 

 goes, certain varieties of cotton would undoubtedly produce well as 

 high up as Matucana, but the weevil would quite certainly be able 

 to maintain itself there and would cause much damage to the crop 

 during the warm growing season. 



The above data are sufficient to show the remarkably complex 

 character of the more or less arid coast to foothill climate of Peru, 

 which exhibits numerous gradations of aridity and humidity with 

 opposites often contrasted in juxtaposition. A comparative study of 

 the weevil in these various districts will not only throw full light 

 on the bionomics of cotton weevils in general, but will indicate those 

 districts of the Peruvian coast and foothills where cotton may be culti- 

 vated with little or no danger of injury by the weevil. 



It is important to point out here the factors which give rise to this 

 climate with its variations. The trade winds sweeping southwest 

 across the Atlantic gather moisture to saturation in their course, which 

 they gradually yield up as they cross the Brazils and ascend the eastern 

 slope of the Andes. Their last particle of moisture is extracted by the 

 snow and ice crests of the Andes, so that when they pass high over 

 the Peruvian coast region they are perfectly dry. The wide Hum- 

 boldt ocean current from the Antarctic region hugs the whole coast 

 of Peru and its waters are about seven degrees Centigrade colder than 

 the superincumbent layers of the air. The winds which blow from 

 the south over this cold ocean current have their moisture largely 

 extracted by it before they can cross it while their temperature is at 

 the same time much lowered; thus when they strike the much warmer 

 littoral precipitation is impossible, and it is only when they arrive far 

 enough inland and high enough up to encounter soil temperatures 

 equal to or colder than their own that precipitation of their residue 

 of moisture takes place. The distance inland and the altitude for this 

 precipitation vary with the season of the year. These data furnish 

 a basis for more or less exact calculations indicating the climatic- 

 variations peculiar to the different districts at different seasons. 



