THE MICROSCOPE AND INSECT LIFE 



disported himself. His next visit was probably to 

 our food. 



If we can find a swiftly running stream within 

 easy reach a little time may be spent in searching 

 the submerged rocks and plants for the miniature 

 stages of the buffalo gnat. This insect, which is 

 known to scientists as Simulium, has a most inter- 

 esting life history. Its popular name is derived 

 from its hump-backed appearance and its supposed 

 resemblance to a buffalo. The female lays her eggs 

 on a rock or reed, just covered by running water, 

 she never lays them in still water. The greenish- 

 brown, club-shaped grubs which come from the eggs 

 are curious and they will repay examination under 

 a low magnification. At the more blunt end of the 

 creature there is a large sucker; it uses this as a 

 foot to support itself in an upright position. If we 

 examine our specimen under water we shall see that 

 its horny head is decorated with a pair of fans, each 

 one composed of about fifty threads. These fans 

 open and close with a rhythmic movement and, in 

 doing so, attract small floating water plants to the 

 mouth. Just below the head there is a single leg 

 with a sucker foot. When the grub walks, it does 

 so by a looping movement, holding fast to its 

 support with fore and hind suckers alternately. 



The next stage in the life of the young buffalo 

 gnat is even more curious. On the surface of some 

 submerged leaf we shall probably be able to find 

 a number of the slipper-shaped pockets made of 

 closely woven silk, in which the insect spends the 



201 



