METAMORPHOSIS
it is provided with food by the parents. Sorne of the wasps store paralyzed insects in the cells of the nest for the young to feed on; the bees give their young a diet of honey and pollen, with an adrnixture of a secretion from a pair of glands in their own bodies. The grubs have noth- ing to do but to eat; they have no legs, eyes, or antennae; each is a rnere body with a rnouth and a stornach. The adult bees consume rnuch honey, which, like its con- stituent, nectar, is an energy-forrning food; but they also eat a considerable quantity of protein-containing pollen. Yet it is a great advantage to the bees in their social lire to have their young in the forrn of helpless grubs that rnust stay in their cells until full-grown, when, by a quick transformation, they can take on the adult forrn and be- come at once responsible rnernbers of the comrnunity. Any parents distracted by the incorrigibilities of their offspring In the adolescent stage can appreciate this. The young mosquito (Fig. ?74 D, E) lires in the water, where it obtains its food, which consists of minute par- ticles of organic rnatter. Some species feed at the surface, others under the surface or at the bottom of the water. The young rnosquito is legless and its only means of pro- gression through the water is by a wiggling rnovement of the sort cvlindrical body. It spends much of its tirne, however, ju?t beneath the surface, from which it hangs suspended by a tube that projects from near the rear end of the body. The tip of the tube just barely ernerges above the water surface, where a circlet of small flaps spread out fiat from its margin serres to keep the creature afloat. But the tube is prirnarily a respiratory device, for the two principal trunks of the tracheal system open at its end and thus allow the insect to breathe while its body is submerged. The adult mosquito (Fig. 174 A), as everybody knows, is a winged insect, the females of which feed on the blood of animais and must go after their victims by use o.f their wings. It is clear, therefore, that it would be quite irn-
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INSECTS
