10 NEW YORK STATE MUSEUM 



Some idea of the varied materials in which the house fly breeds 

 may be gathered from the following: decaying potatoes, decay- 

 ing melons, mixtures of kitchen refuse, paunch contents from 

 animals, bases of stacks of straw or wheat which have become well 

 rotted, ensilage scattered about silos or troughs, chicken manure in 

 poultry houses, fermenting cotton seed hulls mixed with bran, etc.^° 

 In fact, a considerable variety of organic materials, provided there 

 is sufficient moisture and heat and not too much acid, are potential 

 breeding places for this insect and a number of its associates. 



Experience shows that ordinarily flies do not travel great dis- 

 tances, and in most instances probably breed within 300 or 500 feet 

 of the places where they are extremely abundant. This is sup- 

 ported by the fact that very frequently the elimination of a nearby 

 breeding place, such as the removal of a horse from an adjacent 

 barn, is followed by a marked reduction in house flies. Neverthe- 

 less recent studies ^^ by Parker led him to conclude that the house 

 fly is more or less of a migratory insect, and he has succeeded re- 

 peatedly in capturing marked flies a mile or more from the place 

 where they were hberated, even under conditions where it was 

 necessary for the insects to cross a small city with its numerous 

 attractions and traverse comparatively unattractive prairie. There 

 is in addition the record given above of house flies being taken in 

 considerable numbers 5 miles from the point of liberation. A 

 plague of flies on cribs and water works situated 1%, S ^^^ 6 miles 

 in Lake Erie ^' indicated an extended movement or drifting under 

 certain conditions. These records presumably show the approxi- 

 mate maximum flight or drifting rather than the normal spread of 

 large numbers, relatively speaking. The dissemination of these 

 insects is very probably proportional to the attraction and more or 

 less related to weather conditions and air currents. House flies 

 tend to travel either against or across the wind, probably being in- 

 fluenced largely by odors, and fine weather and warm temperatures 

 are important factors. ^^ It is well known that flies may be carried 

 by vehicles of various kinds, especially butcher carts, grocery 

 wagons and electric or steam cars, though it is probable that these 

 agents transport relatively small numbers of insects. These, how- 

 ever, might be important if the flies were carried from centers where 

 contagion aboimded. 



15 Bishopp, Dove & Parman. Jour. Econ. Ent, 8:54-71. 1915. 



16 Parker, R. R. Jour. Econ. Ent, 9 :325-54. 1916. 

 1' Hod^e. Science. 38:512-13. 1913. 



18 Hindle & Merriman. Jour. Hyg., 14:24-25. 1914. 



