COLLECTING FLIES IN THE WEST 



By J. M. ALDRICH, 



Associate Curator, Division of Insects, U. S. National Museum 



Continuing work which has now extended over a period of 40 years, 

 I spent part of June and July, 1930, in making collections of flies in 

 Idaho, Washington, California, and Colorado. 



The vicinity of Lewiston, Idaho, offers a great variety of climate, 

 the city being situated in a deep valley only about 800 feet in altitude 

 while nearby are foothills and mountains rising to about 5,000 feet. 

 The low altitude has a warm climate, with sage-brush and other plants 

 characteristic of the plains region, as well as some which occur much 

 farther south. The higher altitudes are cooler, with more rainfall, and 

 above 3,000 feet are generally forested. Thus there is a wide range of 

 plant life, and a correspondingly great diversity in the insect inhabi- 

 tants. Having lived for 20 years at Moscow, Idaho, altitude 2,700 feet, 

 I have collected extensively over the region ; but there were many flies 

 that I had found only once in the whole time, and undoubtedly others 

 yet undiscovered. In the recent visit I endeavored to collect in as 

 many places as possible in the time at my disposal, with especial 

 attention to those which previous experience had shown to be richest 

 in flies. 



Across the Snake River west of Lewiston lies the city of Clarkston, 

 Washington, at the same altitude. In this warm climate the collecting 

 is better early in the season, and only the late species were obtainable 

 in June. I visited the canyon of Asotin Creek, above the town of 

 Asotin, Washington, on several days, with fair results. Two visits 

 were made to Lake Waha, a small mountain lake 25 miles south of 

 Lewiston at 3,500 feet elevation, among coniferous forests, where 

 many interesting species of flies were found ; this is one of the best 

 places in the region in June. Lapwai Creek ten miles south of Lapwai, 

 Idaho, at an elevation of about 1,500 feet, yielded some valuable infor- 

 mation about the distribution of species and also about their habits. 

 Juliaetta, Idaho, elevation 1,200 feet, in a deep, rocky valley with tim- 

 ber on the precipitous sides, was not so good as on some former visits, 

 the best time for collecting having passed. About 12 miles northeast 

 of Moscow, Idaho, is a small mountain range called Thatuna Hills on 

 government maps, in which the main peak is called Cedar Mountain, 

 but is locally known as Moscow Mountain. This is about 4,900 feet in 



8 107 



