3 ° 
Poisonous Arthropods 
made up of a dilatation forming the body of the pump, in which there 
is a chitinous piston. Attached to the piston is a strong retractor 
muscle. The function of the salivary pump is to suck up the saliva 
from the salivary ducts and to force it out through the beak. 
Of the Hemiptera reported as attacking man, we shall consider 
briefly the forms most frequently noted. 
The Notonectidae, or back swimmers, (fig. igb) are small, aquatic 
bugs that differ from all others in that they always swim on their 
backs. They are predaceous, feeding on insects and other small 
forms. When handled carelessly they are able to inflict a painful 
bite, which is sometimes as severe as the sting of a bee. In fact, 
they are known in Germany as “ Wasserbienen.” 
The Belostomatidee, or giant water bugs, (fig. 19/) include the largest 
living Hemiptera. They are attracted to lights and on account of the 
large numbers which swarm about the electric street lamps in some 
localities they have received the popular name “electric light bugs.’’ 
Our largest representatives in the northern United States belong to 
the two genera Belostoma and Banacus, distinguished from each 
other by the fact that Belostoma has a groove on the under side of 
the femur of the front leg, for the reception of the tibia. 
The salivary glands of Belostoma were figured by Leidy (1847) 
and later were studied in more detail by Locy (1884). There are 
two pairs of the glands, those of one pair being long and extending 
back as far as the beginning of the abdomen, while the others are 
about one-fourth as long. They lie on either side of the oesophagus. 
On each side of the oesophagus there is a slender tube with a 
sigmoid swelling which may serve as a poison reservoir. In addi¬ 
tion to this salivary system, there is a pair of very prominent glands 
on the ventral side of the head, opening just above the base of the 
beak. These Locy has called the “cephalic glands” and he suggests 
that they are the source of the poison. They are the homologues 
of the maxillary glands described for other Hemiptera, and it is by 
no means clear that they are concerned with the production of 
venom. It seems more probable that in Belostoma, as in other 
Hemiptera, it is produced by the salivary glands, though the question 
is an open one. 
The Belostomatidae feed not only on insects, but on small frogs, 
fish, salamanders and the like. Mathcson (1907) has recorded the 
killing of a good-sized bird by Belostoma americana. A woodpecker, 
