These stag beetles during the day crawl about on trees. They fly by night. Their eggs are usually laid in the trunks of old oak-trees.
The larva of the stag beetle has six strong legs and a pair of strong jaws for cutting leaves and wood. The bark, wood, leaves, and roots of the oak and willow are its chief food.
This larva is very large, and lies with its body curled in a half ring. If you look at it, you will see that it has nine round spots down its side, on the rings of its body. It looks as if it wore a coat with big buttons on the side.
Now let me tell you a new wonder. These buttons are the air-holes through which this larva breathes. Come, let us hear the whole story of the insect’s breathing.
You know you draw the air in through your nose and mouth, and this air fills your lungs. You know also that the insect breathes through long, fine tubes. They are kept open with a stiff thread, and wound over all its body.
These tubes have openings for air to pass in and out. These can open and close. In shape they are a little like the lid of a glass jar. These are the holes that we see so clearly along the side of the body of this larva. Both the larva and the pupa must breathe, or they cannot live.
The larva of a stag beetle lives and grows for four or six years; then it passes into the pupa state. When it is ready to change, it makes a case for itself of the fine chips, the juice of which it has been sucking. It binds this sort of coarse sawdust together with glue from its mouth.
When the stag beetle finally comes from this pupa-case, he is a fine-looking fellow. His head and chest are black, with tiny dots like carving. His wing-cases are a deep chestnut.
There are some stag beetles that never get the large, strong horns. We do not know why this is so. Mr. Stag Beetle with the horns fights with and beats his cousins who have no horns.
Stag beetles are fond of fighting. They are like Mr. Crab in that. They have duels with each other.