418 ANNUAL REPORT SMITHSONIAN INSTITUTION, 1921. 



tail wasp (pi. 8, fig. 9), seeking to deposit its eggs beneath the bark 

 of one of the firs. Here, also, the prize of the mountain, Pocota 

 grandis, a large bumblebeelike syrphid (pi. 9. fig. 3), may alight on 

 the panicles of mountain ash or rosy spirsea. 



In the open spaces at the crest of the ridge a group of insects dis- 

 port themselves in the sun. A bee fly of the genus Anthrax (pi. 8, 

 fig. 3) flattens itself against the rocks to absorb to itself whatever 

 heat may radiate, the silver base of its wings reflecting the sun like 

 a mirror. Another bee fly lacks the epaulets, but is equally con- 

 spicuous by its dense coat of crimson hairs. A beautiful but rather 

 rare western fly, Arctophila flagrans (pi. 8, fig. 1), which ranges from 

 Alaska to New Mexico, also frequents this ridge. Here in a few 

 minutes we have seen more specimens than in years of summer moun- 

 tain collecting elsewhere. Two variations of this species occur, one 

 covered with uniformly golden silky hairs, the other with bright red 

 hairs over the abdomen. It is interesting to notice how many of the 

 western flies that mimic bumblebees have a red abdomen, like the 

 common western species of these bees. As would be expected from 

 the presence of the red-tailed mimics, the red-bellied bumblebees also 

 occur on Mount Rainier in abundance. A sister species to Arctophila 

 flagrans was described in 1908 from British Columbia under the 

 name of Arctophila Harveyi (pi. 8, fig. 2). This species is regarded 

 by collectors as one of the most desirable of the popular family 

 Syrphidge. It resembles the white-tailed western bumblebee, Bombus 

 occidentalism in coloration, and is closely akin to the European type 

 of this northern genus, A. hombiformis. Needless to say the dis- 

 covery of this species on Alta Vista was a cause for rejoicing. This 

 fly was not so fond of basking as A. flagrans, but hovered shyly at the 

 edge of a copse and seemed to show a predilection to settle among 

 the twisted flowers of the curious lousewort, Pedicularis racemosa. 



It is characteristic of mountain diptera that many species are 

 mimics, closely resembling wasps, yellow jackets, and bumblebees. 

 This impression may be due to the predominance of the family 

 Syrpliidse which contains many mimetic forms. On Rainier a dearth 

 of yellow jackets is accompanied by a corresponding decrease in 

 hornetlike forms, while the unusual abundance of bumblebees is re- 

 flected in the prevalence of fuzzy-hairy flies. Nowhere in our expe- 

 rience have we encountered more bumblebees than in these flower 

 gardens. 



Even the dead and bared tree trunks produced their quota of 

 interesting species. On Alta Vista a beautiful species of the slender 

 black bee fly, Eclimus (pi. 8, fig. 6) was encountered day after day on 

 the weathered " ghost trees." A tiny fly which proves to be an un- 

 described genus of the Milichiinse was also discovered peering and 



