FAMILY OESTRID.E 269 



after the hatching occurs. The time for the hatching of the 

 eggs is rather important with regard to the treatment of 

 the animaL It has been studied pretty carefully. Dif^'erent 

 statements as regards the period of incubation may mean 

 different species observed. Egg deposition may go on until 

 quite late in autumn, but is usually at its height about 

 August or early September. The activity is retarded by cold 

 weather and the larvae may survive longer then. The method 

 by which they get into the stomach of the horse is by the 

 horse licking itself or some other animal on which there are 

 eggs. At first they are long and slender but after attachment 

 in the stomach become thicker and fasten themselves by 

 hooks to the stomach and remain there through late autumn 

 and winter and early spring. They are sometimes very 

 thickly set in the stomach of the horses. They must cause 

 considerable interference with the activity of the stomach, 

 and if massed together at the pyloric orifice may act as an 

 obstruction. The effect on the animal is in some cases quite 

 evident. The damage is doubtless different in different 

 animals. The worst infested are those that have been in 

 pasture. When they have completed their growth in the 

 stomach they loosen their hold and pass out of the stomach. 

 They burrow into the ground and pupate and remain in this 

 condition several weeks — six or seven — and issue from mid- 

 summer to early autumn. There is one generation a year 

 and the longer period is spent in the body of the animal. 



Treatment for the larvae is rather severe. They may be 

 killed with turpentine, but care must be used not to injure 

 the horse by an overdose. The means of prevention are 

 indicated by the life-cycle — condition of the egg and length 

 of time it may develop. If eggs are removed every week or 

 ten days there is no danger of serious infection. Horses 

 curried regularly are not apt to be infested. They may be 

 shaved off, and this is the most ready means of preventing 

 the infection. Washes could be used to kill the larvte — 

 kerosene, carbolic acid, etc. 



There are three or four species of this parasitic genus in 

 the horse, but no other so common as Gastrophilus equi. 



