158 GOLDFISH VARIETIES AND 
make a very sudden leap towards a victim. The “mask” shown in Figure 
102 when not in use is folded before and under the head. Dragon Fly 
larve are strictly carnivorous at all periods and will attack any pond 
creature reasonably near its own size. If given enough time a single 
individual will destroy an entire hatching of fishes, growing by what it 
feeds upon so as to be able to devour the remaining fishes which are also 
becoming larger. 
Water Boatmen and Back Swimmers (Corixide and Notonectide) 
are found everywhere in still or slow-moving water. They are especially 
plentiful in ponds containing vegetal decomposition and filth, not because 
NO 
Fic. 103. WatTER BoATMAN (Slightly enlarged) 
they like these, but because such conditions are favorable to the growth 
of other creatures making good food for themselves. In daphnia pools 
from midsummer until the end of the season Water Boatmen are fre- 
quently found. Care should be exercised in picking them out of a net, 
as their bite is very severe, the sensation being described as akin to the 
sting of a hornet. Young fishes fall easy prey to these predatory insects. 
They are usually easy to see on account of their jerky, jumping move- 
ments, which are produced by use of their oar-like swimming legs. They 
are obliged to occasionally come to the surface of the water to take air, 
which gives an opportunity of seeing them. Both Water Boatmen and 
Back Swimmers fly clumsily at night, and are often attracted to electric 
lights. In some Southern climates they occur in enormous numbers. 
They are gathered by the natives, dried and sold as fishfood under the 
name of “African Flies.” 
Fic. 104. Prepaczous Divine Bretie (Life size) 
Predaceous Diving Beetle (Dytiscus). Fortunately this beetle is of 
such size that it can scarcely escape notice, especially as it is obliged to 
come to the surface for air, which it takes at the end of the abdomen. 
