202 MUSCID^, OR FLY-TRIBE; MAGGOTS. 



if disturbed, a considerable number of times. Above a hundred 

 species inhabit Britain. In a few of them the larvse are aquatic, 

 and the posterior part of the body is prolonged into a respiratory 

 tube, whence they have received the name of " rat-tailed" larvas. 

 732. The form and habits of the family MUSCIDJE, or Fly 

 tribe, are generally known. The family is an extremely nume- 

 rous one, above 1700 species having been recorded as existing in 

 Europe, of which about half are natives of this country ; and 

 there are probably at least as many more, which have not been 

 described. The strong general resemblance which exists among 

 all the species, together with their small size, makes it difficult 

 to discriminate them readily. The larvae of these insects, com- 

 monly known as maggots^ are soft, worm-like, footless grubs, 

 possessing on the head a couple of retractile hooks, by which 

 they can cling to the substances on which they feed. They 

 devour various substances, both animal and vegetable, living, 

 recently dead, or far advanced in putrefaction. The eggs are 

 deposited by the female (as in other instances) in the neighbour- 

 hood, or in the very substance, of the food which is adapted for 

 the support of the larva, however little this may be to its own 

 liking. Some of these larvas are remarkable for their leaping 

 powers, whence they are commonly termed " hoppers." This 



is especially the case 

 with the larva of 

 the Piophila casea, 

 or Cheese-hopper ; 

 whose mode of 

 springing into the 

 air is very curious. 



FIG. 429.-1. The CHEESE-HOPPER preparing to spring.- When preparing to 

 2. Natural size of the Larva. 3, 4. The Fly to which leap, it first raises 

 it is transformed : natural size and magnified. 



itselt on its tail ; 



in which position it is enabled to balance itself, by means of 

 some prominent tubercles on the last segment of the body. It 

 then bends itself into a circle ; and having brought the head 

 towards the tail, it stretches out the two hooks of the mouth, 

 fixing them into two cavities at the other extremity of the body. 



