DIPTEEA OR TRUE TfLIES. 



229 



apterous, as the sheep-tick and hee-louse. They are cliiefly 

 remarkable in that the female produces her young singly, 

 not as an ovum but as a nearly mature larva or pupariuni. 



The Sheep-tick (Melophagus ovinds). 



Amongst the parasites which are so numerous and destruc- 

 tive to sheep we find one of these Pupipara, the well-known 

 Sheep Spider Fly, " Ked," or Sheep-tick (fig. 116), which, 

 although never fatal in results, 

 yet causes much annoyance to 

 the ewes, and more still to the 

 lambs. We find this pest living 

 amongst the wool, getting close 

 to the skin when we try to catch 

 them. In shape a sheep-tick is 

 flat, with a squarish head, square 

 thorax, and a flat bag -shaped 

 abdomen. There are no wings 

 or halteres, and the whole tick, 

 especially the abdomen and legs, 

 is very bristly. The colour is 

 brown, greyish - brown on the 

 abdomen. The feet have a pair 



of strong hooked claws, each with an accessory side claw and 

 a feathered bristle. The sheep-tick lays her puparia, not eggs, 

 amongst the fleece. The true ova hatch in the body of the 

 female and develop there, until the jjuparium state is assumed, 

 when each puparium is passed out as a bright, shiny, chestnut- 

 brown body, oval in form, with truncate ends. AYhen the 

 female deposits a puparium she fixes it to the wool by a 

 gluey substance, so that it cannot fall ofT. Taschenberg says 

 each female may produce eight such puparia ; the author has 

 found that seldom more than four are so produced. The 

 spider-like fly comes from these shiny, glass-like puparia in from 



Fig, 110. — Sheep-tick (Mdtqjlwgtts 

 ooinus). 



