It were out of place to recall my long relations with the bolete and the agaric if the insect did not here enter into a question of grave interest. Several mushrooms are edible, some even enjoy a great reputation; others are formidable poisons. Short of botanical studies that are not within everybody's reach, how are we to distinguish the harmless from the venomous? There is a widespread belief which says that any mushroom which insects, or, more frequently, their 1arvae, their grubs, accept can be accepted without fear; any mushroom which they refuse must be refused. What is wholesome food for them cannot fail to be the same for us; what is poisonous to them is bound to be equally baneful to ourselves.
This is how people argue, with apparent logic, but without reflecting upon the very different capabilities of stomachs in the matter of diet. After all, may there not be some justification for the belief? That is what I purpose examining.
The insect, especially in the larval stage, is the principal devourer of the mushroom. We must distinguish between two groups of consumers. The first really eat, that is to say, they break their food into little bits, chew it and reduce it to a mouthful which is swallowed just as it is; the second drink, after first turning their food into a broth, like the bluebottles. The first are the less numerous. Confining myself to the results of my observations in the neighborhood, I count, all told, in the group of chewers, four beetles and a moth caterpillar. To these may be added the mollusk, as represented by a slug, or, more specifically, an arion, of medium size, brown and adorned with a red edge to his mantle. A modest corporation, when all is said, but active and enterprising, especially the moth.
At the head of the mushroom loving beetles, I will place a Staphylinid (Oxyporus rufus, LIN.), prettily garbed in red, blue and black. Together with his larva, which walks with the aid of a crutch at its back, he haunts the fungus of the poplar (Pholiota aegerita, FRIES). He specializes in an exclusive diet. I often come across him, both in spring and autumn, and never any elsewhere than on this mushroom. For that matter, he had made a wise choice, the epicure! This popular fungus is one of our best mushrooms, despite its color of a doubtful white, its skin which is often wrinkled and its gills soiled with rusty brown at the spores. We must not judge people by appearances, nor mushrooms either. This one, magnificent in shape and color, is poisonous; that other, so poor to look at, is excellent.
Here are two more specialist beetles, both of small size. One is the Triplax (Triplax russica, LIN.), who has an orange head and corselet and black wing-cases. His grub tackles the hispid polyporus (Polyporus hispidus, BULL.), a coarse and substantial dish, bristling at its top with stiff hairs and clinging by its side to the old trunks of mulberry trees, sometimes also of walnut and elm trees. The other is the cinnamon-colored Anisotoma (Anisotoma cinnamomea, PANZ.). His larva lives exclusively in truffles.
The most interesting of the mushroom-eating beetles is the Bolboceras (Bolboceras gallicus, MUL.). I have described elsewhere his manner of living, his little song that sounds like the chirping of a bird, his perpendicular wells sunk in search of an underground mushroom (Hydnocystis orenaria, TUL.), which constitutes his regular nourishment. He is also an ardent lover of truffles. Ihave taken from between his legs, at the bottom of his manor house, a real truffle the size of a hazelnut (Tuber Requienii, TUL.). Itried to rear him in order to make the acquaintance of his grub; Ihoused him in a large earthen pan filled with fresh sand and enclosed in a bell cover. Possessing neither hydnocistes nor truffles, I served him up sundry mushrooms of a rather firm consistency, like those of his choice. He refused them all, helvellae and clavariae, chanterelles and pezizae alike.
With a rhizopogon, a sort of little fungoid potato, which is frequent in pine woods at a moderate depth and sometimes even on the surface, I achieved complete success. I had strewn a handful of them on the sand of my breeding pan. At nightfall, I often surprised the Bolboceras issuing from his well, exploring the stretch of sand, choosing a piece not too big for his strength and gently rolling it towards his abode. He would go in again, leaving the rhizopogon, which was too large to take inside, on the threshold, where it served the purpose of a door. Next day, Ifound the piece gnawed, but only on the under side.
The Bolboceras does not like eating in public, in the open air; he needs the discreet retirement of his crypt. When he fails to find his food by burrowing under ground, he comes up to look for it on the surface. Meeting with a morsel to his taste, he takes it home when its size permits; if not, he leaves it on the threshold of his burrow and gnaws at it from below, without reappearing outside. Up to the present, hydnocistes, truffles and rhizopoga are the only food that I have known him to eat. These three instances tell us at any rate that the Bolboceras is not a specialist like the Oxyporus and the Triplax; he is able to vary his diet; perhaps he feeds on all the underground mushrooms indiscriminately.
The moth enlarges her domain yet further. Her caterpillar is a grub five or six millimeters long, white, with a black shiny head.
Colonies of it abound in most mushrooms. It attacks by preference the top of the stem, for epicurean reasons that escape me; thence it spreads throughout the cap. It is the habitual boarder of the boletes, agarics, lactarii and russulie. Apart from certain species and certain groups, everything suits it. This puny grub, which will spin itself an infinitesimal cocoon of white silk under the piece attacked and will later become an insignificant moth, is the primordial ravager.
