may be that not one _Sitaris_ in the chamber may reach the adult state. If the first arrival begins to absorb the egg of the _Colletes_, a second hungry one may kill it in the midst of its repast and take its place. But the conqueror finds the provisions already reduced and insufficient to enable it to reach the moulting stage, at the end of which it could profit by the honey. Ill-nourished and weakened, it cannot support this crisis, and its corpse falls beside that of its fellow whom it had sacrificed. Three or four parasites may thus succeed to the same feast, and the victory of the last is useless to him. His first struggle for life and his first triumph are followed by irreparable defeat. These two examples show very well how a slight difference may favour a species, and how a happy quality is capable of being perpetuated by heredity, since by its very nature it is destined to be extended to more numerous beings. [71] "Hypermetamorphoses et Moeurs des Meloides," _Ann. Sc. Nat._, iv. Serie, t. 7, 1857, p. 299; also "Nouvelles observations sur l'hypermetamorphose et les Moeurs des Meloides," _ibid._, t. 9, 1858, p. 265. [Illustration: FIG. 16.] _Carcasses of animals stored up._--These insects lay up for their offspring stores manufactured by themselves or by others. The class we are now about to consider makes provision of animals either dead or in a torpid condition, with more or less art and more or less sure instinct. Most people have seen the _Necrophorus_ or Burying Beetle working in fields or gardens. These are large Coleoptera who feed on abandoned carrion; everything is good to them--bodies of small mammals, birds, or frogs; they are very easy to please, and as long as the beast is dead that is all they require. When they have found such remains, and consider only how to satisfy their hunger, they do not take much trouble, and gnaw the prey on the spot where they have found it. They are not alone at the feast, and in spite of their diligence numerous rivals come up to dispute it; it is necessary to share with a great number of noisy and voracious flies and insects. In the adult state they come out well from this competition; but as good parents they wish to save their larvae from it, as in a feeble condition these might suffer severely. They desire to lay up a carcass for their young alone, and with this object they bury it in the earth. The eggs also which will thus develop in the soil have more chance of escaping destruction by various insectivorous animals. If these diggers find a rat (Fig. 16) or a dead bird, three or four unite their efforts, glide beneath it, and dig with immense activity, kicking away with their hind legs the earth withdrawn from the hole. They do not pause, and their work soon perceptibly advances. The rat gradually sinks in the pit as it grows deeper. When they have the good fortune to find the earth soft they can sink the prey in less than two hours to a depth of