DAIRY INSPECTION 165 



with a spray pump or syringe, is an effective and safe repellent. 

 The following mixture, it is claimed, will act effectively for one 

 week: Soap, 1 pound; water, 4 gallons; crude petroleum, 1 

 gallon, and powdered naphthalene, 4 ounces. The soap is shaved 

 into thin slices and dissolved in the water by heating; the 

 naphthalene is dissolved in the crude oil. The two solu- 

 tions are mixed by stirring vigorously or churning for 15 

 minutes. The mixture is stirred thoroughly each time before 

 using and is applied to the cows with a brush once or twice 

 weekly. While fly repellents afford the cow temporary relief 

 from the biting flies, they are of no value in the control or 

 eradication of the flies. Hellebore and borax have not been 

 tested on the larvae of the cow-fly, but it is very probable that 

 they would be as destructive to these larvae as to those of the 

 house-fly. 



When cows are kept in the stable, with occasional liberty 

 in an exercise yard, the breeding of cow-flies can be prevented 

 by removing the manure from the stable and yard to the fields 

 daily, or if it is stored in the vicinity of the stable, by removing 

 it to the fields at intervals of not less than 12 days, provided 

 the floor of the stable and the floor of the dung-stead are so 

 constructed that the pupae cannot burrow into the ground. 

 When cows are pastured it is not practicable to control the 

 breeding of cow-flies. The manure dropped in the pasture fur- 

 nishes ideal breeding conditions. When the flies emerge they 

 take up a position on the body of the cow, where they feed and 

 rest, and are carried into the stable by the cow. 



The stable-fly breeds in horse manure and in decaying grass 

 and straw heaps ; also in cow droppings which have become dry 

 and disintegrated, and in ensilage. Eggs deposited in these 

 substances hatch out larvae in 1 to 3 days. The larvae develop 

 into pupae in 11 to 30 days or more, and the flies emerge in 

 6 to 20 days, the time from the egg to the fly being 18 to 53 

 days and upwards. The stable-fly feeds on the blood of cows 

 and other domestic animals, and also bites man. Unlike the 

 house-fly, it is not likely to infect milk with bacteria, since it 

 does not feed upon that substance. 



