Packard ] INSECTS OF THE POND AND STREAM. 141 
water and an orifice is formed by the separation of the hairs 
at the end of the keel, which form the larger part of the 
mouth of the orifice, the remainder being composed of the 
hairs fringing the movable terminal plates of the body. 
The air thus passes in between the false deck of hairs and 
the under side of the body. When the insect is taken out 
of the water the hairs cling to the sides of the body, reveal¬ 
ing very distinctly the breathing holes. Some air occasion¬ 
ally penetrates under the elytra and remains there most of 
the time. Often the whole under side of the body between 
the pairs of legs is a continuous bubble, like a mass of quick¬ 
silver or molten lead. The Notonecta often rises for a new 
supply of air before the old is exhausted. 
While handling Notonecta thoughtless of its reputed sting, 
in a quiet business-like way it inserted its beak in my thumb, 
the pain almost as severe as the 
sting of a wasp, and lasting for 
five minutes. The pain was too 
acute and benumbing not to be 
the effect of a poison. If no 
poison sac will 3 r et be found in 
the head, then the saliva must 
be an acrid poison. By this 
poisonous sting it must para¬ 
lyze its victims. 
Another water bug, the Co- Corixa. 
rixa (Fig. 104, enlarged), is less 
tame and does not come to the surface nearly as often as 
Notonecta. It receives its supply of air in an instant and 
darts down to the bottom. It does not swim in an inverted 
position. It takes in the air so suddenly that it is impos¬ 
sible without long and patient observation to sec the mode, 
which we have been unable to find described. It rises to 
the surface in a horizontal position and no sooner is the sur¬ 
face reached than it darts to the bottom, and in one instance 
13 
Fig. 104. 
