444 NATURAL HISTORY OF HARTING. 



Craterina Hirundinis, another winged insect, bearing 

 a close family resemblance to Hififobosca, infests the 

 swallow, and we have found both the perfect fly and 

 its egg-cocoon in the nest of this bird. On one occa- 

 sion we picked up a dead swallow, the body of which 

 was still warm, and while in the act of parting its 

 feathers to ascertain if it had been wounded, we un- 

 expectedly disturbed one of these parasites, in an 

 instant it was on the back of our hand, and the 

 difficulty we experienced in removing it even from 

 the bare skin, left us in no doubt whatever of the fact 

 that it would be absolutely unmanagable among the 

 feathers of a bird. 



The term " fly," in its general application to insects 

 materially differing from each other in almost every 

 external character, was no doubt originally intended 

 to refer to those only that possess the faculty of flight. 

 To any one who still understands it in this sense, a fly 

 without wings would appear to be an anomaly, yet 

 such an insect is our next and last example in this 

 order MelopJtagus ovinus. This parasite inhabits the 

 woolly covering of the sheep, and it is evident that in 

 such a dense tangle wings .would not only be useless 

 to it, but would actually impede its progress. It is 

 popularly known as the sheep-tick, or sheep louse, but, 

 as we have already said, it is a true fly, though utterly 

 destitute of both wings and poisers, in other particulars 

 it is not unlike Hippobosca and Craterina, and it is so 

 tenacious of life that it has been found alive in a fleece 

 twelve months after the latter had been shorn. 



