56 



OHIO EXPERIMENT STATION: BULLETIN 356 



depending upon the temperature. Assuming that the grubs ma- 

 ture in April, then the flies would be present during May and per- 

 haps June and July. But it is not likely that all the grubs mature 

 at the same time, so the flies are probably present during May, 

 June, July and August, and possibly later. Since we have in the 

 parasite collection only two specimens of the adult flies, reared from 

 the grub stage, a statement of the seasonal appearance of the fly in 

 Ohio cannot be definitely made. 



Control. — While the life stages of this pest have long been de- 

 scribed, its habits and relative abundance under different methods 

 of flock management still remain subjects for investigation. New 

 and adequate methods of combating the sheep bot fly may result 

 from information thus obtained. 



Sinuses of sheep's head invaded by Oestrus larvae 

 From Bureau of Animal Industry, U. S. D. A. 



Remedies now commonly recommended consist of the applica- 

 tion of some repellent, such as tar, to the sheep's nose to keep the 

 flies away and trephining to remove the grubs in case they become 

 injurious to valuable sheep. 



SHEEP MAGGOTS 

 Symptoms and Injury. — The maggots usually attack the flesli 

 in the region of the rump or the horns. They have hatched from 

 eggs deposited by flies attracted to the wool soiled with urine or 



