69 



the Opantia or Prickle Pear : this consists of thick 

 leaves, and its fruit resembling a fig, is full of a crimson 

 juice, to which the insect owes its colou-r. 



When first hatched, it is scarce bigger than a mite, 

 and runs about very swiftly; but it soon loses its ac- 

 tivity, and fixing on the least and most juicy part of 

 the leaf, clings there for life, without moving any 

 more, only for its subsistence, which it sucks in with 

 its proboscis. 



The male has no appearance of belonging to the same 

 species : they are smaller than the female, have wings, 

 and like the butterfly, are continually in motion : they 

 are constantly seen among the females, walking over 

 them, as it were carelessly, and impregnating them. 

 But it is the female only which is gathered for use, four 

 times in the year, for so many are the generations of 

 them. 



The most singular part of the life of a Drone- Fly. is 

 that it passes in the form of a worm. It is then dis- 

 tinguished from all .other worms by its long tail : at 

 different times this is indeed of different lengths ; but 

 it is always lunger than the worm itself. It is round, 

 smooth, and very small at the extremity ; sometimes 

 no thicker than a horse-hair. To know the use of this 

 tail, we must first know the nature of the worm it^e!f. 

 It is an aquatic, and never leaves the water lili it 

 changes into its fly. state. They lie in multitudes in 

 the 'mud at the bottom of vessels of stinking water. 

 Put them into vessels of clean water, and they will soon 

 shew the use of their taiis. Though they live under 

 water, they cannot live without breathing fresh air: 

 this is the end to which their long tails serve; for even 

 while they lie buried in the mud, their tails are ex- 

 tended to the top of the water, and being open at the 

 extremity, let air into their bodies. And as soon as 

 they are in a vessel of fresh water, they get to the bot- 

 tom and thrust up their tail to the surface. They can. 

 lengthen them at pleasure : to be assured of this, you 

 need only pour HI more water. The worms them 



