SOME PESTS OF OHIO SHEEP 59 



hardens and assumes a dark brown tint. On the inside of this 

 pupa-case wonderful changes take place, resulting in a perfect fly. 



This fly probably winters over in the pupa-case, since pupae 

 were found in the pen, which contained a fly-blown sheep, under- 

 neath the bedding in late October. Larvae placed in an outside 

 cage in late fall were found in the pupa stage in the early spring. 

 On May 18, 1917, two adult flies were taken from this cage and one 

 plump pupa was found. Later, June 13, an adult fly emerged 

 from this pupa-case. On June 17, four adults flies were taken from 

 the cage. These flies lived until June 22 (5 days) without food or 

 water. 



BLACK BLOW FLY 



Phormia regina Meigen 



The black blow fly has been reared from larvae working in 

 blood-stained wool around the horns of rams pasturing together. 

 Thus this fly differs from the "blue bottle" in that it is attracted to 

 and deposits its eggs in wool, stained from bruises or minor skin 

 injuries. The eggs, according to F. C. Bishopp (Farmers' Bul- 

 letin No. 857) hatch in from less than 24 hours to 4 days. From a 

 collection of larvae received from Carpenter, Ohio, July 24, 1918, 

 pupae were formed 5, 7 and 8 days later. Adult flies emerged from 

 the pupal cases 9 days later. Of another collection received 

 August 21, 1916, the pupal stage lasted from 7 to 8 days. Sum- 

 marized, the length of time from egg to fly may range from 13 to 21 

 days. The adult fly is considerably larger than the house fly and 

 greenish black in color. It is very prolific and usually becomes 

 very abundant during the late summer. 



Control. — Careful examination at intervals of a few days of 

 each member of the flock during the summer and early fall months 

 is recommended. Soiled wool likely to attract the flies may be re- 

 moved or treated with some deodorant in order to counteract the 

 smell that attracts the flies. If sheep are blown, the infested wool 

 should be sheared off, all the maggots removed and killed and the 

 infested area rubbed with a crystal of blue stone (copper sulphate). 

 The Ohio Station has found the copper sulphate treatment very 

 effective if used in the early stages of the infestation. It dries the 

 infested area and stops the decomposition which gives rise to the 

 putrid smell that attracts the flies. Reinfestation is thus pre- 

 vented. Crutching is recommended and used in Australia as a 

 blow fly preventive. 



Sheep infested over a larger area are not so easily cured. The 

 infested wool and all the maggots should be removed. To remove 



