78 LIFE HISTORY OF HABRONEMA. 



IX. — The stable fly, Stomoxys calcitrans Geoff. 



Both Hill and Bull have shown that this fly is apparently 

 the normal transmitter of H. microstoma, but they have 

 pointed out that the pai^asite may at times undergo 

 abnormal development in Musca domestica. They, moreover, 

 failed to infest Stomoxys with either H. ynuscce or H. 

 megastoma. Hill (p. 32), in one of his experiments in 

 which he examined five pupae and 16 adult Stomoxys, all 

 infected, found them to contain from 4 to 50 lai-val 

 H. microstoma, the average l)eing about 25. He mentioned 

 having obtained as many as (30 in one fly, 35 being in the 

 proboscis and head, and 25 in the thorax and abdomen 

 (p. 33). Linstow (1875) discovered larvae in the heads 

 of two out of 41 stable flies examined by him. His figures 

 and measuremeints of Filaria stomoxeos from this host- 

 species agree sufficiently with those given by Hill for the 

 arvse of H. microstoma for one to assume that the names 

 are synonymous. 



Hill examined 03 captured Stomoxys, finding only 

 one infected, this containing only one larval Habronema. 

 Ten pupae and 12 larvae were collected and examined with 

 negative results. Both Hill and Bull, however, reported 

 that experimental infection of the stable fly with 

 H. microstoma was verj- readily brought aljout. Graham- 

 Smith (1914, p. 241) found Stomoxys infected naturally 

 at Cambridge, England, the percentage ranging from four in 

 1908 to 13 in 1910. The parasite was regarded as being 

 probably H. 7nuscce. 



As Stomoxys was very scarce in the Eidsvold district 

 we were not able to carry out any experiments with it, 

 and had to content ourselves with examining only 18 

 specimens (June, Julj', 1919), none of which were found 

 to harbour larvae. We might mention that we did not 

 observe in any of the flies examined there, any Habronema 

 resembling the larval stages of H. microstoma. 



We have recently (February, 1920) examined four 

 specimens of the fly bred out from horse dung collected 

 in Brisbane, and have found two infected, one containing 

 in its proboscis six worms, and the other only one, all of 

 which agree with the description given by Hill for 



