DESCRIPTIONS OF THE LARV.l^: OF SOME MOTHS FROM 

 COLORADO. 



By Hakrison G. Dyar, 



Custodian of Lepidoptera. 



With the sanction of the Secretary of the Smithsonian Institution, 

 I spent three months in Colorado in the wuimner of 1901, to investigate 

 the life histories of some of the moths of that region. As Colorado 

 embraces several different faunal regions, and as the arid condition of 

 the countr}' renders the fauna very sparse and sporadic, different con- 

 ditions are found to obtain there than in the Atlantic region in the 

 matter of collecting. It was found impossible to move about so as to 

 cover various faunal reg-ions without losing the larva? already collected 

 in one place, owing to the impracticability of keeping a fresh supply of 

 food plants. 1 located in Denver and collected mainly on the prairies 

 and foothills within 20 miles of that place. Mr. A. N. Caudell, of the 

 Department of Agriculture, accompanied me, and was allowed to assist 

 me b\" the permission of the entomologist of that Department. 



The species of Lepidoptera occurring- in Colorado indicate four 

 faunal regions in the State. (1) The prairie fauna occupies all the flat 

 land from the bases of the foothills eastward, probably including- the 

 eastern third of the State and reaching to Texas. It is composed 

 largely of species peculiar to the region. The ver}' dr}^ condition of 

 this land and the sparse vegetation, mostly disappearing early in the 

 season, with the absence of trees, renders this condition necessary. 

 (2) The fauna of the foothills occupies the hilly and uneven land from 

 the bases of the mountains up to timber line. The line of division 

 between this fauna and that of the prairie is very marked. The foot- 

 hills rise quite sharply from the plains, and within a few paces, almost, 

 the change in the fauna is observable. The foothills have a few trees, 

 pine, and other evergreens, with a dwarf oak, all sparsel}^ distributed; 

 a hard}^ bush, Cerocarpus pannfoUm, seems to prefer the most unfa- 

 vorable hill tops. In the bottoms of the canyons, where water persists, 

 Cottonwood, willow, and other trees occur, often densely, which per- 

 mits the occurrence of many species belonging to the Atlantic region 



Proceedings U. S. National Museum, Vol. XXV— No. 1290. 

 Proc. N. j\I. vol. XXV— 02 24 369 



