This parental love is even evinced by insects who never see their offspring. The butterfly uses the utmost care in selecting a suitable leaf on which to deposit her eggs. She selects one that will be nourishing food for the larvæ when hatched out, and, after carefully observing whether it is preoccupied by the eggs of some other butterfly (in which case she abandons it), she proceeds to deposit her eggs. "Having fulfilled this duty, from which no obstacle short of absolute impossibility, no danger however threatening, can divert her, the affectionate mother dies."[56]
[56] Kirby and Spence, _Entomology_, p. 228.
The gadfly uses a like forethought in selecting a place for her eggs. The larvæ of the gadfly (_OEstrus equi_) are developed in the stomach of the horse, so the provident mother attaches the eggs to the hairs of the foreleg between the knee and the shoulder, a place the horse is almost certain to lick with his tongue and, in this manner, convey the eggs to his stomach, where they are hatched out. The breeding place of certain of the ichneumons is the body of a caterpillar. The ichneumon may be seen busily searching the bushes for her victim. When she finds it, she inserts her ovipositor into its body and lays her egg. If some other ichneumon has preceded her, she recognizes the fact at once, and will not deposit her egg, but will go in search of another grub. When the egg is hatched, the larva feeds on the body of its host, carefully avoiding the vital organs. The caterpillar retains just enough vitality to assume the pupa state, and then dies. The chrysalis discloses, not a butterfly, but an ichneumon.
The mason wasp (_Epipone spinipes_) builds its cells and lays its eggs, one in each cell. It then hunts and procures spiders, which it deposits in the cells and then seals the openings. These spiders are not killed outright, but are partially paralyzed by the sting of the wasp. The insect thus secures for her young a supply of fresh food. This wasp not only knows the difference between the eggs that will produce female young, but she also makes this knowledge useful. She always supplies the females with more spiders than she does the males. The females are larger and require more food, hence the discrimination. All of this care and forethought is expended on young which the mother will never see. Human love cannot give greater evidences of complete unselfishness.