All living creatures must hunt for food, and insects eat a great deal for their size. Beetles are very heavy feeders. They eat most when they are grubs, but some, like Cockchafers and Tiger-beetles, eat almost as much when they are full-grown and have their wings.
There are plant-eating beetles, and beetles which feed on other insects and animals. Altogether there are more than 3,000 species of beetles in the British Isles. It is useful to know what kind of food a beetle eats, for some do good work in the fields and gardens, while others do great injury to the crops.
One of the most mischievous is the Cockchafer. You know him quite well when he flies in your face in the evening. But perhaps you do not know him as a grub, when he lives for three or four years underground, and eats the roots of the grass, corn, and vegetables. If you see plants in the cornfield or garden looking sickly and yellow, and drooping their leaves although the ground is damp, it is most likely that there is a grub underneath, and it may be the grub of a Cockchafer.
Dig up the plant and you will find an ugly white creature (3, Plate, p. 30) like a huge maggot, almost as thick as your little finger, with a red head and very strong jaws. It has six long legs, with five joints, growing on the rings behind its head, and is so full of food that it can hardly crawl. The end of its tail is swollen into a thick cushion, and you can see the breathing all along its sides very clearly because it is so distended with food. You remember that it does not take in breath through its mouth, so it can go on eating all the time. If you had not disturbed it, it would have crept on from plant to plant across the field, doing nothing but eat for three years. It goes down deeper in the ground in winter to keep warm during the frosty weather.
At last in the autumn of the third year it draws itself together (4, p. 30), and leaves off eating for nearly eight months. If you can find one at this time you will be able to see the parts of the real beetle crumpled up under the clear skin, and for the last few months it will be a full-grown sleeping cockchafer.
Then, when the warm summer comes, it crawls up above ground and flies into the trees, eating their leaves as greedily as it ate their roots while it was a grub. This is the time to catch and kill them, for they only live about a month, and meanwhile the mother cockchafer lays the eggs which will hatch into grubs.
You will be surprised to see how different the beetle is from the white grub you found underground. It is now a flying insect, about half an inch long, with brown powdery wing-cases, covering a pair of transparent wings. Its hind-body, or abdomen, ends in a fine point, and on its head it carries a pair of feelers tipped with broad folds like a half-open fan.
These folds are very handsome in the male Chafer (1, p. 30), but much smaller in the female (2), and by this you may know the mother which will lay the eggs. You must catch and kill these last if you want to save your crops, and the most merciful way to do this is to drop them into boiling water. A crushed beetle is a long time dying, but boiling water kills them at once.
You will find that they rest in the daytime on favourite trees, and, if you spread a cloth underneath, you may beat the boughs and so catch a good many. Farmers use gas-lime and other dressings to kill the grubs in the ground.
Another very mischievous creature is the young of the Skipjack or Click-beetle (5, Plate, p. 30). All children know these little beetles, though perhaps you may not know their name. They are narrow and flat, about half an inch long, with very short legs. The most common one in England has reddish wing-cases, striped with long furrows, and a black head and thorax. Boys love to pick them up, and turn them on their backs, for they bend themselves up in the middle so as to rest on their head and tail. Then with a sudden jerk and a click they straighten themselves, so that their back hits your hand and sends them up in the air, and they come down the right way up. Sometimes they fall again on their backs, then they rest a little and begin again.
These amusing little creatures are very destructive when they are grubs, for the wireworms we know so well are the young of the Click-beetle. If you find a wireworm and look at it carefully you will see that it is not a worm, but has the six legs on the rings behind its head, by which you know that it is an insect. Wireworms feed on the roots of most plants. They are long and narrow like a piece of wire, and are generally of a reddish yellow colour, and have very tough skins.
The Click-beetle lays her eggs in meadows, and among the roots of plants, and the wireworm when it is hatched often feeds for five years before turning into a beetle. Therefore Click-beetles must be destroyed, and salt and lime sprinkled on the earth to kill the grubs.
Unfortunately the pretty little Weevil-beetles are also very destructive. We read in Book I. about the Nut-weevil, and almost every plant and tree has some weevil which attacks it. There is the weevil of the apple-blossom (4), the Pea-weevil (1 and 2), the Bean-weevil (3), the Furze-weevil, the Vine-weevil, and many others. They all begin life as little soft maggots with no true legs, but only cushion feet, and with horny heads and sharp jaws.
You may know the full-grown weevils by their prominent snouts, sometimes broad and sometimes long. They are beautiful little creatures with polished wings which shine like jewels, and bright eyes; but as grubs they destroy the flowers, fruits, and green shoots everywhere.
Some of the most curious are the Stem-boring weevils. They have long snouts and very sharp jaws, and their feet have hairy pads underneath with sharp hooks at the end, so that they can cling firmly to smooth stems. If you search on the poplar tree in summer you may find a lovely Stem-borer with shining green wings and red eyes; and on the fruit trees of the orchard you are almost sure to find the Steel-blue weevil which lays her eggs in their shoots.
When the mother stem-borer wants to lay, she bores a hole in a young shoot with her snout and forces an egg into it. When she has laid several in this way, she sets to work to cut off the shoot with her sharp jaws. This often takes her some weeks, and if you see the hanging shoot and burn it you will destroy the grubs. But at last, when it hangs by only a thread of bark, she weighs it down, and it falls to the ground, where the grub feeds in peace when it is hatched.
Try to find Cockchafers—male, female, and grub. Bring in a Click-beetle and a Wireworm. Find as many weevils as you can; and twigs, flowers, and fruit with grubs in them.