INSECT SUCKERS AND BITERS. 213 
body along these infinitely fine branching canals. 
Here we have the secret why insects leap, and 
fly, and run so easily. Think how beautifully light 
a body must be which instead of containing solid 
flesh is full of channels of air. Lyonnet counted 
1572 tubes in a caterpillar's body, and even then 
left many smaller ones unnoticed ; while some 
insects, such as the bee and the grasshopper, have 
not only air-tubes but actual bladders of air filling 
large spaces in the body. Nor is it only lightness 
which insects gain by this network of air -tubes, 
for their blood being bathed in air is always full of 
oxygen, and therefore active and vigorous, supplying 
their nerves and muscles with strength quite beyond 
what we should expect for their size, and helping us 
to understand why they have been so successful in 
the battle of life. 
So the grasshopper with his large fixed eyes with 
many hundred windows in them (for structure see p. 
224), his delicate feelers, his strong jaws, his long 
muscular hind legs, and his light body, is an active, 
powerful insect, and an especially greedy feeder. 
Indeed he has between his throat and his stomach 
an apparatus called a gizzard, with more than 200 
teeth in it, for grinding the food which he has stripped 
off the bushes and meadows with his cutting jaws. 
Even our little grasshoppers in the meadows and the 
large green grasshopper living in the trees devour 
greedily all that comes in their way, but their ravages 
are as nothing compared with those of the large 
migratory locusts with short antennae, which multiply 
at an incredible rate in favourable seasons, and move 
in swarms over the south of Europe, darkening the 
