264 FBKSH-WATEE AQtTAEIA. 



C. annulatus is tlie larger of the two, and is able to inflict the 

 more painfiil wound. The curious humming noise made by 



Gnats is caused by the exceed- 

 ingly rapid vibration of their 

 wings. It is said to be only 

 the females who make this 

 sound. It " has been calcu- 

 lated," says one writer, " that 

 the Gnat vibrates its wings 

 3,000 times a minute," but 

 P\^^ — another writer records that 

 the sirene proves the vibra- 

 tions to be 15,000 a second! 

 Fig. 161. Common Gnat mi /-»7 • -j ht-j 



(CuLEx ciLiARis). The Uhironomidce, or Midges, 



are chiefly distinguished from 

 gnats by their proboscis, which, instead of being long and 

 homy, is short and fleshy. They are very gnat-like in 

 appearance. Their antennse are long and plumed, especially 

 those of the males. The antenna is so plumed as to be of 

 a triangular shape. The "bite" of a Midge is not nearly so 

 painful as that of a gnat; and many of the Midges are 

 altogether harmless. These insects, like the gnats, spend the 

 larval and pupal portion of their lives in the water. 



The members of the genus Corethra are the most gnat-Uke 

 of all the Midges. One species, C. plumicornis, is very 

 common, and its larva is one of the most interesting and 

 decidedly the most extraordinary of all aquatic larvse. This 

 creature is sometimes called the "Phantom Larva" or the 

 " Glass Larva." It well earns such names, for it is so trans- 

 parent that there is no little diflB.culty in seeing it in the water; 

 and through the translucent sides of the animal the greater 

 portion of its internal organisation is plainly visible. Its 

 specific gravity seems to equal that of the water, so that, 

 without any effort at all, it can remain at the top, middle, or 

 bottom of the water in which it lives, as it thinks fit. This 

 interesting larva is slightly more than ^in. long, about -jijin. 

 deep, and less than this broad. It gradually tapers towards 

 the tail. Its head has somewhat the appearance of a rabbit's 



