198 



THE STABLE FLY, STOMOXYS CALCITRAXS LINX. 



The recent investigations in Massachusetts, U.S.A., by Brues, 

 Sheppard and Rosenau (see 1911 to 1913), on the relation of 

 S. calcitrans to poliomyelitis or infantile paralysis, in which they 

 experimentally demonstrated the ability of the fly to transmit 

 the disease to healthy monkeys, which experiments Avere con- 

 firmed in Washington by Anderson and Frost (1912), have resulted 

 in increased attention being paid to this species, which is now 

 being studied by a number of investigators including myself In 

 later experiments Anderson and Frost (1913) failed to confirm 

 their previous results ^ 



t:^- 



Fig. 89. Head of Stomoxys calcitrans L. Left lateral aspect. 



Stomoxys calcitrans is slightly larger and more robust than 

 M. domestica, measuring about 7 mm. in length. It can be readily 

 distinguished by the awl-like proboscis which projects horizontally 

 forward and slightly upwards from beneath the surface of the 

 head (fig. 89). The bristles of the antennae bear setae on their 

 upper sides only, as in the allied Glossina. The general colour is 

 brownish or greyish with a greenish tinge ; the dorsal side of the 

 thorax has four dark longitudinal stripes, the outermost pair 

 being interrupted. At the anterior end of the dorsal side of the 

 thorax the medium light-coloured stripe has a golden appearance 

 Avhich is very distinct when the insect is seen against the light. 



^ In a more recent paper Sawyer and Herms (1913) describe a series of experi- 

 ments in which they were unable, imder varied conditions, to transmit poliomyelitis 

 from monkey to monkey through the agency of ,S'. calcitrans. 



