HEAD AND THORAX 9 
But if we observe the head of a squash bug, we find no jaws or other 
parts that would serve to chew or bite. Instead there is a stout beak, 
and if we were to dissect this, we should 
find that it contained a tube for sucking 
up plant juices or other fluids. In ad- 
dition, we should find in most insects of 
this type, two or three pairs of lancets within 
or close to the beak, used to puncture or 
rasp the tissucs so as to induce a greater 
flow of the 
juices. 
Insects with 
biting mouth 
parts may be 
killed by cov- 
ering the plant 
on which they 
feed with a 
poison, such as 
lead arsenate. Fre. 7.— Mouth parts of a 
Fic. 6.— Mouth parts of Bat tasects horsefly, fitted for pierc- 
a honeybee. Enlarged. | Page ing and sucking. Enlarged. 
Original. with sucking Original. 
mouth parts 
do not eat the surface of the plant and cannot be killed by applica- 
tions of stomach poison. For the latter other remedies must be 
used, such as some substance that will kill the insect by corrosive 
action on its body. 
The Thorax 
The middle part of an insect’s body is called the thorax. Usually 
it has three distinct rings, or segments. On cach segment is a pair 
of legs and on each of the last two is a pair of wings, except in the 
group of two-winged flies, which have only a single pair, on the middle 
segment. 
An insect’s leg consists, typically, of a small joint next the body, 
the trochanter; a large and heavy joint, the femur; a slender tibia; 
