Packard] INSECTS OF THE POND AND STREAM. 135 
be subaquatic, and in its structure and habits connects the 
Carabids with the Dytiscidse. 
Out of the immense number of species of butterflies and 
moths, but three or four genera are known to be aquatic. 
The larvae of Hydrocampa, Cataclysta and Paraponyx, small 
moths of the family of Pyralidae, live in the water on the 
leaves of aquatic plants, the caterpillar of Paraponyx being 
provided both with branchiae and spiracles. M. Bar has 
lately discovered in French Guiana a hairy caterpillar which 
Fig. 97. 
lives in the water, and resembles that of our Arctia or 
“ woolly bear.” It has no tracheal branchiae, and all the 
spiracles except those on the segment behind the head and a 
pair on the end of the body are smaller than usual. 
There are no truly aquatic Hymenoptera or Orthoptera. 
The aquatic Hemiptera, such as Gerris, Notonecta, a €orixa 
and a few other forms, all breathe atmospheric air, though 
the stigmata may be elongated and otherwise modified for 
the purpose. One spider, the Argyroneta of Europe, is 
7 
