Another brood of bees appeared the middle of September, as on the ninth of that month (1864) Mr. Emerton found several holes of the same species of bee, made in a hard gravel road near the turnpike. When opened, they were found to contain several bees with their young. September 2nd, of this year, the same kind of bee was found in holes, and just ready to leave the cell. It is probable that these bees winter over.
We have incidentally noticed the presence in the nests of Andrena and Halictus of a stranger bee, clad in gay, fantastic hues, which lives a parasitic life on its hosts. This parasitism does not go far enough to cause the death of the host, since we find the young of the parasitic Cuckoo bee, in cells containing the young of the former.
Mr. F. Smith, in his "Catalogue of British Bees," says of this genus: "No one appears to know anything beyond the mere fact of their entering the burrows of Andrenidæ and Apidæ, except that they are found in the cells of the working bees in their perfect condition: it is most probable that they deposit their eggs on the provision laid up by the working bee, that they close up the cell, and that the working bee, finding an egg deposited, commences a fresh cell for her own progeny."
He has, however, found two specimens of Nomada, sexfasciata in the cells of the long-horned bee, Eucera longicornis. He also states, that while some species are constant in their attacks on certain Halicti and Andrenæ, others attack different species of these genera indiscriminately. In like manner another Cuckoo bee (Cœlioxys) is parasitic on Megachile and Saropoda; Stelis is a parasite on Osmia, the Mason bee: and Melecta infests the cells of Anthophora.
The observations of Mr. Emerton enable us still further to clear up the history of this obscure visitor. He found both the larva and pupa, as well as the perfect bee, in the cells of both genera; so that either both kinds of bee, when hatched from eggs laid in the same cell, feed on the same pollen mass, which therefore barely suffices for the nourishment of both; or the hostess, discovering the strange egg laid, cuckoo-like, in her own nest, has the forethought to deposit another ball of pollen to secure the safety of her young.
Is such an act the operation of a blind instinct? Does it not rather ally our little bee with those higher animals which undoubtedly possess a reasoning power? Its instinct teaches it to build cells, and prepare its pollen mass, and lay an egg thereon. Its reason enables it, in such an instance as this, when the life of the brood is threatened, to guard against any such danger by means to which it does not habitually resort. This instance is paralleled by the case of our common summer Yellow bird, which, on finding an egg of the Cow bunting in its nest, often builds a new nest above it, to the certain destruction of the unwelcome egg in the nest beneath.
In the structure of the bee, and in all its stages of growth, our parasite seems lower in the zoölogical scale than its host. It is structurally a degraded form of Working-bee, and its position socially is unenviable. It is lazy, not having the provident habits of the Working-bees; it aids not in the least, so far as we know, the cross-fertilization of plants—one great office in the economy of nature which most bees perform,—since it is not a pollen-gatherer, but on the contrary is seemingly a drag and hinderance to the course of nature. But yet nature kindly, and as if by a special interposition, provides for its maintenance, and the humble naturalist can only exclaim, "God is great, and his ways mysterious," and go on studying and collecting facts, leaving to his successors the more difficult task, but greater joy of discovering the cause and reason of things that are but a puzzle to the philosophers of this day.
The larva of Nomada may be known from those of its host, by its slenderer body and smaller head, while the body is smoother and more cylindrical. Both sexes of Nomada imbricata and N. pulchella were found by Mr. Emerton, the former in both the Andrena and Halictus nests, and both were found in a single Andrena nest.
Wood Wasp.