552 



The Sheep Maggot Fly. 



[dec, 



to one-half of an inch in length ; the head end is pointed and 

 provided with two mouth hooks ; the hind end is blunt with 

 tubercles round its margin, and two plates carrying the spiracles 

 on its flat surface. Examination of the first segment behind 

 the head with a good lens would show the spiracle to be fan- 

 shaped and with ten little prominences. Professor Carpenter 

 points out that a blue-bottle maggot would show in the same 

 situation thirteen such prominences. 



The pupa cases are brown and rounded or barrel- shaped, and 

 the fly when ready issues by a hole at one end. 



Life History. 



The female fly is ^capable of laying as many as 500 eggs, and 

 fixes these in clusters of twenty and more to the wool. These 

 eggs may hatch in favourable conditions in twenty-four hours, 

 and the maggots feeding at first externally, later bore into the 

 flesh. By a fortnight they may be full grown, when they drop 

 away from the sheep and become pupae under cover of the 

 barrel-shaped case. It was found by experiment that the flies 

 issued in from less than a fortnight to over a fortnight, according 

 to temperature and other conditions. 



The attack is worse on lambs than on old sheep, and the flies 

 are found at work from May onwards till the autumn. Moist, 

 warm, muggy weather, and warm sunshine after showers favour 

 the fly. 



Loss. 



Direct loss from death is not likely where careful oversight 

 by the shepherds is possible, such loss being most likely in hill 

 pastures. Indirect loss is heavy from the disturbance to the 

 flock by the continual hunting and collecting. " Struck " sheep 

 also thrive badly and are depreciated in value partly from this 

 and partly from disfiguration. 



Preventive and Remedial Measures. 

 1. Cleanliness. Sheep should be kept thoroughly clean 

 about their hindquarters, A good preventive is to clip the 

 wool of the tail and between the hind legs, docking the tails of 

 sheep when too long. The purpose is to clear away any filth 

 and to leave as little chance as possible for lodgment, for the 

 flics have a keen sense of smell and are attracted to dirty places 



