THE INSECTS, 
109 
in the sides of the body. There are in many insects two 
pairs of thoracic and eight pairs of abdominal spiracles. 
The anatomy of the grasshopper may also be compared 
with that of the western cricket (Fig. 131). 
The antennae are both organs of touch and also of smelly 
the olfactory organs being little pits ; some insects, how- 
ever, hear with their antennae. The locusts have a pair of 
large ears situated at the base of the abdomen (Fig. 128). 
Insects produce sounds in various ways, either as in 
locusts by rubbing the legs against the closed wings, or by 
rubbing the upper on tlie under or hind wiugs; while some 
insects produce creaking sounds by rubbing the harder 
parts of the body together. 
In walking or running, an insect, as a beetle (Fig. 132), 
raises and puts down its six legs alternately, as may be 
seen by observing the movements of any large insect. - 
The wings are broad thin bags or expansions of the skin. 
They are strengthened by hollow rods called veins, of 
which there are six principal ones. The veins are hollow, 
usually containing an air- tube. 
The wing of an insect in making the strokes during flight 
describes a figure 8 in the air. A fly's wing makes 330 rev- 
olutions in a second, executing therefore 660 simple oscil- 
lations. 
According to M. Phiteau, who has recently made ingen- 
ious experiments regarding the strength of insects, the 
smallest of these animals are proportionally the strongest. 
A cockchafer can pull 21 times more, proportionally, than 
a horse, while a bee pulls thirty times more. (The ani- 
mals were attached to a cord passing over a pulley to a 
weighted scale.) The horse lifts 6-7ths of its weight, the 
cockchafer 14 times its weight, and the bee 20 times. 
Insects are very prolific, laying hundreds of eggs. Some 
insects, as the cricket, grasshopper, and ichneumon fly, 
possess a horny tube called an ovi2JOsitor, by means of 
which they bore into wood or the earth and deposit their 
eggs one after another. 
