330 JOURNAL OF ECONOMIC ENTOMOLOGY [Vol. 9 



the Northern Pacific and the Chicago, Milwaukee & St. Paul railroads. 

 The principal business section may be roughly included within a tri- 

 angle having the Northern Pacific Railroad as its base and Fifth and 

 Pleasant streets as its sides. 



In speaking of "fly conditions" at Miles City the writer has used 

 the word "natural." The expression "fly conditions" refers to those 

 conditions, the variability of which affects the existence of the house 

 fly favorably or unfavorably, e. g., presence or absence of breeding 

 materials and their availabihty, presence or absence of garbage and 

 how it is cared for, etc. The term "natural" means that "fly con- 

 ditions" are very favorable, both for their spread and multiplication. 



Description of Release Points 



Laboratory (release point number 1). — The Laboratory was sit- 

 uated about midway on the eastern edge of the city. Directly east 

 there were no houses; to the northeast there were but few south of the 

 railroad, but more beyond it to the north; to the south of the North- 

 ern Pacific tracks the houses extend eastward to some distance beyond 

 the street on which the Laboratory'' was located, but are somewhat 

 scattered; in all other directions the city was well built up. The 

 best residential section was about one-eighth mile to the west. Figure 

 10 shows the Laboratory as seen from the Northern Pacific tracks 

 with the city in the background. 



Flies released at this point had been captured in several Hodge traps 

 set on a table in the rear of the building. Flies were abundant due 

 to garbage and manure piles near by. 



Sales Yards (release point number 2).— The Sales Yards (PI. 25, fig. 

 7) are located southwest of the central portion of the cit}^ and just be- 

 yond its limits. In all thej^ cover 44| acres of which 24j are in 

 pens. They are both north and south of the tracks of the Northern 

 Pacific railroad. The houses are scattered in the vicinity of the pens 

 to the south and the nearest of these is 300 yards from the pens -to the 

 north in which we are most interested. The latter cover nine acres 

 and are the most productive breeding grounds. Except for a few 

 houses in the vicinity of Station 109, the business section of the city 

 along Fifth street (-400 to 530 yards) is the portion of the city north of 

 the railroad which is nearest the yards. It is also the most insani- 

 tary section. Between this and the release point lies the city park (PL 

 25, fig. 4) and a narrow belt of woodland along the old channel of the 

 Tongue river. Figure 1 was taken looking toward Miles City from 

 the west and shows the locality' of the release point, while PL 25, fig. 2 

 was taken from this release point looking directly toward the city. 

 The City Dump release point was about 800 yards north and slight- 



