94 COCOONS, BUT NOT OF SILK. 
The caterpillars are rarely found except on 
these sand hills; and they are very conspicuous, 
being of a black colour, with red lines, and 
white and yellow spots. They are easily found 
by the birds of the sea-shore, and afford them 
a supply of food. 
The earth-digging caterpillars are all of the 
same family, but they belong to different species; 
and each species buries its cocoon a little deeper 
than the other. As for instance, one caterpillar 
will spin a web upon the surface of the ground, 
and weave in leaves and bits of stick, to hide it. 
Another will go a step farther, ’ and though it 
keeps still on the surface, will build its cocoon of 
earth, and make it look on the outside like a 
little mound. A third will press down the mould 
till it has made a hollow place, like a grave, 
where it will cover itself up, and lie just below 
the ground. A fourth will dig a little deeper, 
and another deeper still, and so on, until at last, 
one caterpillar will bury itself at least a foot 
below the ground, before it begins to make 
its cell. 
If you were to dig up one of these earthen co¬ 
coons, you would take it at first to be nothing 
but a clod of mould. But if you broke it open, 
you would see that its outer wall was made of 
pellets of earth, fastened together with gum; and 
