The young are fed for several days, then shut up in the cells and allowed to form pupæ. Eventually they break their cells and take their place as workers in the hive, first as nurses for the young and later as pollen gatherers and honey makers.
We have already seen (pages [37] to 39) that the honeybee gathers nectar, which she swallows, keeping the fluid in her crop until her return to the hive. Here it is forced out into cells of the comb. It is now thinner than what we call honey. To thicken it, the bees swarm over the open cells, moving their wings very rapidly, thus evaporating some of the water. A hive of bees have been known to make over thirty-one pounds of honey in a single day, although the average is very much less than this. It is estimated from twenty to thirty millions of dollars' worth of honey and wax are produced each year in this country.
Cochineal and Lac.—Among other products of insect origin is cochineal, a red coloring matter, which consists of the dried bodies of a tiny insect, one of the plant lice which lives on the cactus plants in Mexico and Central America. The lac insect, another one of the plant lice, feeds on the juices of certain trees in India and pours out a substance from its body which after treatment forms shellac. Shellac is of much use as a basis for varnish.
Gall Insects.—Oak galls, growths caused by the sting of wasp-like insects, give us products used in ink making, in tanning, and in making pyrogallic acid which is much used in developing photographs.
Insects destroy Harmful Plants or Animals.—Some forms of animal life are of great importance because of their destruction of harmful plants or animals.
An insect friend of man. An ichneumon fly boring in a tree to lay its eggs in the burrow of a boring insect harmful to that tree.
A near relative of the bee, called the ichneumon fly, does man indirectly considerable good because of its habit of laying its eggs and rearing the young in the bodies of caterpillars which are harmful to vegetation. Some of the ichneumons even bore into trees in order to deposit their eggs in the larvæ of wood-boring insects. It is safe to say that the ichneumons save millions of dollars yearly to this country.
Several beetles are of value to man. Most important of these is the natural enemy of the orange-tree scale, the ladybug, or ladybird beetle. In New York state it may often be found feeding upon the plant lice, or aphids, which live on rosebushes. The carrion beetles and many water beetles act as scavengers. The sexton beetles bury dead carcasses of animals. Ants in tropical countries are particularly useful as scavengers.
Insects, besides pollinating flowers, often do a service by eating harmful weeds. Thus many harmful plants are kept in check. We have noted that they spin silk, thus forming clothing; that in many cases they are preyed upon, and that they supply an enormous multitude of birds, fishes, and other animals with food.