THE FLY. 69 



Although the foregfting calculation is quite suffi- 

 cient to account for the immense swarms of Flies 

 that make their appearance during the summer and 

 autumn months, yet these would be considerably in- 

 creased were it not that, from various causes (such as 

 drought, flood, &c., and the rapacity of birds and other 

 animals that prey upon them), a considerable number 

 of the eggs thus deposited are never hatched; or if 

 hatched, the larvae are, from similar causes, destroyed 

 in that stage, and do not attain the imago form. The 

 eggs are hatched a few days after they are deposited ; 

 and if you wish to obtain a tolerably accurate idea of 

 the appearance of the larva that proceeds from them, 

 you have but to examine with a pocket-lens one of 

 the weU-known long white maggots, commonly termed 

 "jumpers," which are found in decaying cheese, and 

 afterwards become converted into a small black Fly 

 [Piophila] belonging to a kindred group; or one of 

 the ordinary maggots found in ham when ia a state of 

 decay. 



The body of the larva (PI. VIII. fig. 1 & 1, a) is 

 divided into thirteen rings, of which the anterior, or 

 head, is furnished with a pair of hooked jaws, and 

 curious globular palpi (PL VIII. fig. 4), and the 

 second bears a pair of rudimentary feet (fig. la,2). 



The jaws, along with the remaining apparatus 

 situated upon the first ring, are capable of being 

 retracted, and they then present the appearance de- 

 computes the number of ova deposited to be above 2,000,000,000, 

 and Schwammerdam counted 140 eggs in tlie body of one Fly. 



