june, '16] parker: dispersion of musca domestica linnaeus 329 



Objects of Investigation 



Realizing that in Montana cities and towns, with the possible 

 exception of a few of the larger cities, conditions are quite similar, ex- 

 cept as regards the extent of territorj^ covered, it was felt that inves- 

 tigations on dispersion conducted in a city of medium size would lead 

 to results of general application. With this idea in mind the objects 

 of the summer's work may be stated as general and specific, the latter 

 referring to the special problems of the city concerned. 



General Objects. — (1) To determine the distance from breeding 

 grounds to which flies may be expected to travel under city conditions 

 and the amount of territory over which they may spread, (2) to de- 

 termine what factors control dispersion under city conditions. 



Specific Objects. — (See Plate 23.) (1) To determine the radius 

 of dispersion from the Laboratory, (2) to determine the radius of 

 dispersion from the Miles City Sales Yards, (3) to determine the 

 radius of dispersion from the City Dump, (4) to determine the radius 

 of dispersion from the Washington School, (5) to determine the factors 

 which controlled this dispersion. 



These release points were dictated by local conditions and were so 

 selected as to give an idea of the possible dispersion from breeding 

 grounds variously located with reference to the city as a whole. 



Local Conditions 



As previously stated, Miles City offered unusually good opportu- 

 nities for experimental work. The horse sales yards (PI. 25, fig. 7) just 

 west of the city, probably the largest in the world, furnished a breed- 

 ing ground of great extent from which flies bred out in many millions. 

 Many partially or entirely uncontrolled breeding places throughout 

 the city added their quota. 



The built-up portion of the city is perhaps two square miles in area 

 and may roughly be included within a square one and one-half miles 

 on a side. Thus the size of the city was such that it would permit 

 the application of results to practically all Montana cities and towns 

 and j^et not too large to be covered during a season's work. 



Regulations dealing with the removal of manure, etc., were in ex- 

 istence, but local conditions prevented their application in a way that 

 would be effective. The Cit}^ Dump to which refuse was supposed to 

 be carried was scarcely outside the city limits. 



Except along the business section of Main street the buildings are, 

 for the most part, well separated. Xo section would in any way 

 correspond to the congested areas with high buildings and narrow 

 streets found in so many large cities. 



The most closely populated portion of the city is that lying between 



