254 DIPTERA OR TRUE FLIES. 



cowsheds, and pigstyes is called the Biting Fly [Stomoxys 

 calcitrans), which sucks the blood out of animals, and even 

 attacks man : it is one of the true Muscidse. It is provided 

 with a sharp piercing proboscis (fig. 145) with which it pene- 

 trates the skin of its victim. 



Ticks, Forest Flies, &c. (Eproboscidea). 



The Eproboscidea are the Sheep-ticks, Forest or Horse Flies, 

 and Bird Flies. They are generally called Pupipara, and 

 present many peculiarities, which can only briefly be referred 

 to here. Some resemble spiders in appearance, but the number 

 of their legs soon identifies them. They are all parasitic in 

 habits, living upon warm-blooded animals. Some are quite 

 apterous, as the sheep-tick and bee-louse. They are chiefly 

 remarkable in that the female produces her young singly, not 

 as an ovum but as a nearly mature larva or puparium. 



The Sheep-ked (Melophaqus ovinus). 



Amongst the parasites which are so numerous and destructive 

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

 Spider Fly, "Ked," or Sheep Tick (fig. 146), which, although 

 never producing fatal 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 it. In shape a sheep-ked is flat, with a squarish head, 

 square thorax, and a flat bag-shaped abdomen. There are no 

 wings or halteres, and the whole insect, 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-ked lays her puparia amongst the fleece. The true ova 

 hatch in the body of the female and develop there, until the 

 puparium state is assumed, when each puparium is passed out 



