Numeric dimorphism follows dimorphism of mass; the family of one sort of butterfly of the Marquesas Islands is composed of one male and of five females all different, so different that one long supposed them distinct species. Here the advantage is obviously on the side of the male lord of this splendid harem. Nature, profoundly ignorant of our sniveling ideas of justice and equality, vastly pampers certain animal species, while showing herself harsh and indifferent to others; now the male is favoured, now the female, upon whom the greatest mass of superiorities is heaped, and upon whom likewise all the cruelties and disdains. The hymenoptera include bees, bumble-bees, wasps, scolies, ants, masons, sphex, bembex, osmies, etc. The place of these among insects is analogous to that of the primates or even of man among mammifers. But while woman, not animally inferior to her male, remains below him in nearly all intellectual activities, among the hymenoptera the female is both brain and the tool, the engineer, the working-staff, the mistress, mother, and nurse unless, as in the case of bees, she casts upon a third sex all duties not purely sexual. The males make love. The male of the tachyte, a sort of wasp rather like the sphex, is about eight times smaller than the female, but he is a very ardent small lover, marvellously equipped for the amorous quest; his citron-coloured diadem is made of eyes, is a girdle of enormous eyes, a lighthouse whence he explores his horizon, ready to fall like an arrow upon the loitering female. When fecundated, the she-tachyte constructs a cellular nest which she packs with the terrible mantis, of whom she is the always victorious enemy; for knowing by incomprehensible instinct whether she is about to lay a male or a female egg, she augments or diminishes, according to its sex, the larder for the larvæ the tiny male is allotted a dwarf provision.
The male hornet is notably smaller than the female, and the neuter hornet still smaller. The male pine lophyr is black, the female yellow. The male of the chalicodome or mason-bee is russet, the far more beautiful female is a fine velvety black with deep violet wings. While the male loafs and bumbles she artfully and patiently rears the big-domed clay nest where her offspring pass their larvæ days. This bee lives in colonies but the labour is individual, each doing her work without bothering about that of her neighbour, unless it be to rob her or spoil her construction, as in a civilization not unknown to us. The female mason is armed, but by no means aggressive.