540 GEOLOGICAL SUEVEY OF THE TERRITORIES. 



CMonohas Semidea being tlie most abundant. Of the moths, the beauti- 

 ful Arctia Quenselii, which occurs also on Mount Washington, New 

 Hampshire, and in the Alps, seemed to have the most extensive geo- 

 graphical distribution. If the sun were shining, the Lepidoptera might 

 be seen flying about with all the activity of species in a warmer climate 5 

 but if a passing cloud obscured the sun for a few moments, they 

 quickly took refuge in the rocks, so sensitive did they seem to a change 

 of temperature. 



The spiders appeared to thrive best ; being always present at all eleva- 

 tions, and apparently indifferent to climate. The geometrical web-spin- 

 ners were rarely found at high altitudes, owing to the absence of trees 

 and plants upon which to build their webs. The habits of the species 

 found above the timber-line were, however, well adapted to their 

 peculiar surroundings. Those found in the crevices of rocks and holes 

 in the ground generally lined their habitations with silk, and were thus 

 enabled to entrap their prey ; but the greater number were true wan- 

 derers, and roamed from place to place without ever spinning webs. 

 Twenty- three species were found above timber-line, and, as far as now 

 known, they are nearly all new to science. 



The plant-bugs {Hemiptera), as might be supposed from the almost 

 total absence of vegetation, were not numerous. This order of insects 

 was found to be very limited in species throughout the mountains, 

 owing probably to the scarcity of the cultivated plants found in more 

 civilized regions, upon which they feed. The vegetables, fruit, and 

 grain raised in the foot-hills are consequently quite free from the attacks 

 of these pests, which so much annoy eastern farmers. 



The collection of flies {Diptera) was so much damaged in transporta- 

 tion that it was difficult to determine even the genus in many cases. It 

 is to be hoped that future collectors will not overlook this interesting 

 order of insects, and that they may be more fortunate in preserving 

 their collections- from the many mishaps inseparable from mountain- 

 travel. The horse-flies (Tabanidce) were found in great numbers at the 

 timber-belt, but seldom ventured far above it, and were never seen on 

 the summit of the higher peaks. The blow-fly. (illMsm erytJirocephala) was 

 found everywhere at all elevations, and seriously interfered with the 

 preservation of natural-history specimens, besides proving very 

 destructive to articles of food at altitudes below 10,000 feet. 



The bee-order is well represented in the collection ; four new species 

 of Hymenoptera being found. The humble-bee was always to be seen 

 in midsummer at the verge of the alpine flora, busily engaged in col- 

 lecting its store of pollen from the few flowers to be found. 



The principal and most interesting result obtained from the study of 

 this collection, is the demonstration of the fact that the alpine insect- 

 fauna of the Kocky Mountains is nearly identical with that of Mount 

 Washington (New Hampshire), Labrador, and Alaska ; and that insects 

 which are found upon mountains at great elevations will likely occur in 

 a much higher latitude at a less elevation. 



Insect-life, with the exception of the grasshoppers, is more abundant 

 in the foot-hills than the plains near the foot of the mountains. An 

 altitude of about seven thousand feet appeared to produce the greatest 

 variety of species. 



I desire to express my thanks to Dr. A. S. Packard, jr., for valuable 

 assistance rendered in the determination of species; also • to Prof. T. 

 Glover, of the Agricultural Department, who kindly placed his admira- 

 ble entomological plates and the i^ublic collections at my service. 



