Roubaud observed that the young females of Belonogaster remain in the nest for eight days and during this time receive the nutritive morsels which they chew and distribute among the larva? "after having eaten a certain portion of it" In exchange for this privilege, which allows time for their ovaries to ripen, they devote themselves to the care of the nest and await for the coming day of coupling. Once f ertilized, they become in their turn egg-layers, and then are attached to the nest by new bonds,-the gratification which egg-laying gives them by satisfying the ovarian apparatus, and their liking for a liquid rejected by the mouth of the larva? which they know wonderfully well how to collect. It is an individual interest which keeps them in the nest and which makes them work in the common interest, that is to say to assure better the preservation of the species. Aside from the egg-laying, which is an accident with the workers, the same factors of colonization apply to the whole group of social wasps. The larvae of our Vespa, observes Eobert du Buysson, "have the faculty of secreting an abundant liquid from the mouth. When they are touched, there suddenly appears a large transparent drop which covers the larger part of the face. The queen, the workers, and the males are fond of this secretion and they know how to excite the larvae to furnish them this beverage." Between the larvae and the adults a food exchange is established, a trophobiosis. Eoubaud says:
Wasp societies are trophobiotic societies, dependent on the exploitation of the larvae. They tend toward maximum production, in an individualistic way, of the larvae. The maternal love of the wasps, which is shown in the perfect care which they take of their young in feeding them from the beak like birds, does not differ at bottom from the feelings which ants have for plant-lice and scale-insects, which they cultivate for their secretions.
We also believe, with Eoubaud, that individual interest is not without weight in the societies of ants and termites. Forel observes, in fact, that the eggs of ants as soon as laid receive the attention of the workers, which, "are constantly occupied in licking them." Bugnion has stated, on the other hand, that the eggs of the termites of Ceylon are "bathed in a covering liquid at the moment of laying," that they "are submitted first to the operation of licking," and that without this operation they cannot develop. Is this not then again a phenomenon of trophobi-osis?
We cannot extend this to the bees, for the worker bees can gain no advantage from the eggs nor from the larva?, especially with the Meliponas, where the provisionment is great. But the young of all the Mellifera have the advantage of being born in an already prepared nest, and all without doubt enjoy to a certain extent the privileges which the young honey-bees have. We know, indeed, that at the moment of their birth the young bees are cared for and brushed by the older workers, that afterward these stay in the nest to act as nurses, and that they as well as the larva? benefit from the provisions collected by the others. They do not leave a lodging where the hospitality is so great!