MOUSE BOT-FLY 



315 



Eggs and Larvae. The moisture and friction which these 

 receive from the animal licking its hair cause them to hatch, and 

 further licking, occasioned possibly by the irritation of the skin 

 caused by the presence of the tiny larvae, carries the maggot into 

 the mouth. It finds its way into the horse's stomach, and there 

 completes its larval life, attached to the lining of the stomach. 

 It is sometimes so abundant as to completely cover a portion of 

 the stomach (Fig. 322). Normally the egg stage lasts about 

 fifteen days. Evidently, if the eggs go four weeks without being 

 licked, a very small percentage, if any, of them will hatch. The bots 

 live in the stomach or intestines eight or ten 

 months, moulting twice during that period. 



Injury. Naturally, when numerous, 

 they sap the vitality of the horse. They also 

 cause great irritation by attaching them- 

 selves to the lining of the small intestines 

 and the rectum. City horses, whose drop- 

 pings fall mostly on pavements and in other 

 places unfavorable for the development of 

 the bots, are not so subject to the pest as 

 are the animals in the country. 



The Next Season. In the spring these 

 bots loosen their hold and pass out with the 

 droppings ; they work their way into the soil 

 an inch or two, or into some protected local- 

 ity; each "bot" or larva changes to a pupa, 

 lying within a pupal case, from which the 

 adult fly emerges after about thirty days. 



Control. A horse will not be attacked so long as he is in the 

 stable. Ordinarily a stable horse can be kept free of what few 

 "nits ".it attracts, while out of doors, by proper currying, and no 

 careful man in charge of horses will allow the eggs to remain on 

 the animal or animals in his charge. Horses hi pasture and not 

 being groomed frequently become covered with eggs during sum- 

 mer and early fall, and such animals should be carefully examined 

 every two weeks and all "nits" removed. The eggs can be cut 

 off or killed by a trace of kerosene just brush them over with a 

 feather wet in the oil and do not use enough kerosene to injure 

 the hide. Or they may be killed by the use of a wash consisting of 

 one part of carbolic acid in thirty parts of water. We can resort 

 to clipping when eggs are deposited in numbers. The eggs may 



I 



FIG. 321. Eggs of horse 

 bot-fly, attached to hairs. 

 Greatly enlarged. 



