VIII, B, 1 Mitzmain: Stomoxys calcitrans Linnseus 47 



mobilize it by strapping to a frame of brass wire. This was 

 done in order that movements of the animal would not interfere 

 with the biting of the flies or with the observation of the flies 

 throughout feeding. Cropping the hair of this host was found 

 to facilitate the feeding of the flies. It was necessary to hold 

 the museum jar horizontally with the bottom toward the light. 

 Here the majority of flies assemble when not feeding, and 

 the light reactions of the fly are taken advantage of in withdraw- 

 ing and introducing the host. If desired, ether can be used 

 to advantage in the transfer of animals. It should be applied 

 at the screened end of the jar, lightly enough to prevent flight, 

 but not sufficiently to stupefy the insects. The flies can also be 

 fed individually in test tubes to guinea pigs strapped to stocks, 

 being applied to some convenient part of the body, preferably 

 the side of the abdomen. 



Horses. — The method more commonly employed by investiga- 

 tors is to enclose both the flies and the horse in a screened stall 

 or shed. Here it is not possible to make close and accurate 

 observations, and despite the fact that many thousands of flies 

 could be kept at once they did not, in my experience, live longer 

 than eight days, and usually died in five days even when food 

 was constantly available. 



By strapping the horse to an operating table, accurate data 

 of the feeding process can be obtained. This method supplanted 

 the crude one of throwing the horse to the ground and feeding 

 flies from inverted bottles. The violent struggling of the horse 

 under these conditions is not conducive to making accurate 

 observations. 



In all of the methods of feeding the flies, the hair of the host 

 was closely cropped with scissors. It was found advantageous, 

 also, to slightly dampen the skin of the host to make the animal 

 odor more attractive to the insect and to arouse its blood-drawing 

 instincts. 



SUMMARY 



1. The age at which Stomoxys calcitrans begins eg^ laying 

 has been determined in bred flies to be nine days. 



2. The maximum number of eggs produced by a single Stom- 

 oxys may be stated as at least 632 and possibly 820. As many 

 as 20 depositions may be made in the lifetime of a female. 



3. The incubation period for these eggs is from twenty to 

 twenty-six hours at a temperature of from 30° to 31° C. 



4. The larval stage under optimum conditions is usually from 

 seven to eight days. 



