SOME PESTS OF OHIO SHEEP 



55 



the larvae crawl down the nasal passages and fall to the ground 

 where they pupate. We have in the parasite collection nearly 

 mature larvae collected on March 3 and on April 15. The former 

 specimens were found in the cavity of the horn and probably would 

 have matured the latter part of April The latter specimen pro- 

 bably would have matured in May. 



We have only one note on the length of the pupal stage, which, 

 however, is incomplete. On March 29, 1918, five bot-fly pupae were 

 received from Carpenter. When found, in the manger of a sheep 

 pen, they were in the larval stage. The transformation from the 

 larval to the pupal stage took place during transit from Carpenter 

 to Wooster, or within a period of 3 days. 



Sinuses of sheep's head invaded by Oestrus larvae. From Bureau of 

 Animal Industry, U. S. D. A. 



Upon receipt the pupae were placed in an insect-rearing cage. 

 On May 23 or 55 days later, the soil over the pupae was removed. 

 Two of the pupariums were empty. Evidently two flies had 

 emerged. A search revealed a male and female in the folds of cloth 

 covering the hole in one side of the cage. Frequent observation of 

 the cage failed to display an adult fly, so it was assumed that none 

 had emerged. How long since these two had emerged is of course 

 not known. The flies were dead when found. No flies ever 

 emerged from the remaining pupal cases. According to various 

 authorities the length of the pupal stage varies from 40 to 50 days, 



