1916 ENTOMOLOGICAL SOCIETY. Ill 



Pupal Period for H. bovis. 



Miss Ormerod (1900) puts the pupal period at 25-36 days = 32.5 days. 



Carpenter (1908) at 31-32 days. (1914, about 8 weeks. Not included in 

 average) . 



Hadwen (1912) at 34.7 days. 



Glaser (1913) gives an average of 44 days. 



Lucet (1914) records an average of 32.5 days. 



Averaging all these records gives a result of 35 days. 



If then, the last larvae emerge about the first of July, the season for flies 

 cannot extend far into August, and my records show this to be the case. 



The Effect of Temperature on the Pupal Period. 



I have already shown (1914) that if the pupas of H. lineatum are placed in 

 an incubator that the fly will emerge in as short a period as 13 days. This year 

 I placed several larvae of H. bovis in an incubator kept at 80 °F. The pupal period 

 was shortened to 17.4 days. 



Pup^ Kept in Incubator at 80°F. 



Period. 



2 larvae pupated May 1st Emerged 1* It May 19th 19 days. 



3 " " 3rd " 3 " 20th 17 " 



1 " " 4th " 1 " 20th 16 " 



1 " " 5th " 1 " 21st 16 



2 " " 6th " 1 " 22nd 18 



As the temperature at which the pupa is kept causes early or late emergence, 

 the situation in which the larva finds itself on leaving its host will make some 

 difference also. An experiment I hope to carry out next spring is to place some 

 pupae in a situation such as the edge of a manure-pile; here the larvae would 

 derive heat much in the same way as if placed in an incubator. Others must 

 find crevices in the floors of stables, etc., where they would be warmer than out 

 of doors. These warm situations would mainly favor H. lineatum and the early 

 larvae of H. bovis. Later in the season, when the sun is stronger in June and 

 July, I do not think the places the larvae choose to pupate in can matter so much. 

 But early in the year it is quite possible that some of the early appearances of 

 H. lineatum may be accounted for in this way. 



An Experiment made to prove how H. bovis engenders Fear in Cattle. 



July 1st, 3 p.m. Two calves which had been kept inside since they were 

 born, were turned out into a small paddock. The cattle which had previously 

 occupied the paddock, had just been put into the stable,, and the flies had been 

 chasing them a few minutes before. The two calves on being liberated at once 

 began to caper about and run as calves will after they have been confined. Finally 

 they came to a halt just in front of me. They stood there panting. A moment 

 or two later I saw a single H. bovis attack one of the calves. It struck several 

 times before it was noticed. Finally I saw the calf give a kick or two. then it 

 turned its bead round to see what was annoying it. There were some more kicks 

 and stamps, then the calf began to move away, its tail went up and it began to 

 run and finally to gallop. The other calf remained standing for a short time 



• Male. t Female. 



