A CONTRIBUTION TO THE KNOWLEDGE OP BOT-FLIES. 99 



be impossible for the host to lick the eggs with its tongue by reason of their 

 inaccessibility, the young larvae, instead of being taken into the mouth, penetrate 

 into the body directly through the integument ? This would undoubtedly account 

 in satisfactory fashion for the small lesions which were noted. This theory receives 

 additional support from the fact that in several of our experiments many eggs hatched 

 independently, unaided by either moisture or friction, in a glass vial. 



In reviewing the literature, it is interesting to note that Brumpt (10), p. 699, quoting 

 Henry, says that the eggs of G. nasalis are laid on the cheeks and intermaxillary 

 region of the horse and are entirely adherent to the hairs, a fact with which we readily 

 agree. This same author, in a footnote, also quotes Raillet, on page 699, as stating 

 that the first-stage larvae of this same species are probably the cause of " creeping 

 myiasis " on the cheeks of the horse, indicating that he found a condition similar 

 to that already noted in our observations. 



Similar scabby pimples have been diagnosed on the lips of the horse, on the hairs 

 of which the eggs of G. haemorrhoidalis are generally found. In this case, however, 

 the eruptive condition might be satisfactorily explained, in the absence of approved 

 evidence, by the host rubbing its lips violently on the ground. At the height of 

 the season, the adult fly was frequently observed to goad its host into behaving thus, 

 especially when the " striking " was persistently repeated. Further, the rubbing 

 of the lips was severe enough to cause the complete removal of the hairs. 



On 20th August 1917, a piece of skin, the hairs of which bore numerous eggs of 

 G. intestiwalis, was removed from the umbilical region of a foal recently killed. To 

 prevent its decay, the skin was treated with bichloride of mercury. In all, only 

 three eggs hatched unaided, one on 25th August and the remaining two on 29th 

 August. The larvae which emerged from these three eggs died among the hairs 

 and apparently made no effort to burrow beneath the skin. Results of a similar 

 kind were obtained with the eggs of the same species when another piece of skin was 

 taken from the antero-intero-inferior region of the knee of a horse which had recently 

 died, and likewise treated with bichloride as before. No larvae emerged of their own 

 accord from the eggs deposited on the investing hairs. Therefore, from these two 

 casual experiment, no evidence was forthcoming that the recently emerged larvae 

 of G. intestinalis may penetrate directly beneath the integument. 



On 18th September, a small piece of the buccal mucosa was removed from the inside 

 of the lower lip of a horse and placed in a petri dish. Recently emerged larvae were 

 obtained from the eggs mentioned in the two previous experiments and hatched by 

 the aid of moisture and friction. In all, 9 live larvae were placed on the skin, which 

 was kept moist by the application at intervals of a few drops of normal salt solution. 

 The experiment was commenced at 7.30 p.m. By means of the binocular microscope, 

 some of the larvae were observed to be actively working their mouth-parts. The 

 head-hooks were extended and opened out in a lateral direction. This behaviour 

 was continued for a time. Finally, the mouth-hooks were embedded in the skin as 

 if preparatory to the larvae tunnelling beneath the surface. At 10 p.m., they were 

 still actively engaged in the work, but no single one had made any extensive headway. 

 The most successful had not penetrated further than the second anterior segment. 

 Nevertheless, the fact remains that the mouth-hooks were securely fixed, so much 



