Ho. 4*] Reprints. 22^ 



hold and are carried through the intestines and, escaping with the 

 excrement, burrow into the ground to pass the pupa stage. This 

 lasts for several weeks, thirty to fourty days, according to some 

 authors, when the fly, which has been already described, issues and 

 is ready to proceed with the business of providing for another 

 generation of bots. 



The larva of this species has been found in the stomach of the 

 dog, though it cannot be considered a normal habitat for it, and it 

 is very doubtful whether the young larvae could survive in the 

 stomach of a carnivorous animal. Railliet (Comptes Bendus des seances 

 de la Societe de Biologic, 1894) cites records by Colin and others of 

 such occurrences, and details experiments which show the possibility 

 of the survival of nearly mature larvae that are swallowed with 

 fragments of the stomach walls attaching: to the stomach of the 

 dog and remaining alive and healthy fifteen days after the ingestion. 



Prevention. — In dealing with bots in horses, by far the most 

 important point is to prevent the introduction of the larvs, and 

 while we have no opportunity, as in the case of the ox bot-fly, to 

 completely exterminate the pest, it is certain that proper attention to 

 preventive measures would in a few years greatly reduce the 

 numbers of the insects and procure comparative freedom. The 

 better care usually accorded horses makes it possible to deal with 

 it in some respects more easily than the species infesting cattle. 

 The most vulnerable point of attack lies in the conspicuous position 

 of the eggs. No horseman probably can overlook these objects 

 when occurring on the horse he is caring for, and colts in pasture 

 sometimes become so covered with them as to give a decided change 

 in colour to the parts most affected. It is evident that removing 

 or destroying these eggs previous to hatching is all that is necessary 

 to prevent "bots" in the horse. With horses kept in stables or 

 used daily there is little trouble ; the flies have less opportunity to 

 deposit eggs upon them, and the ordinary grooming of the animal 

 serves to remove some of the eggs, or being constantly under observa- 

 tion the eggs attract the attention of the person in charge and 

 he removes them, if not to prevent bots at least to avoid the unsightly 

 or ill-kept appearance they give the animal. With colts or horses 

 in pasture, however, the case is very different. Not knowing the 

 curry-comb or card through the whole summer, and perhaps hardly 

 seen from one week's end to the other, the eggs deposited on 

 them by hundreds have every possible chance to transmit larvae 

 to the alimentary canal where they commence their growth. During 



