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, I found 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.
Let us next mention the arion, that voracious mollusk who also tackles most mushrooms of some size. He digs himself spacious niches inside them and there sits blissfully eating. Few in numbers, compared with the other devourers, he usually sets up house alone. He has, by way of a set of jaws, a powerful plane which creates great breaches in the object of his depredations. It is he whose havoc is most apparent.
Now all these gnawers can be recognized by their leavings, such as crumbs and worm holes. They dig clean passages, they slash and crumble without a slimy trail, they are the pinkers. The others, the liquefiers, are the chemists; they dissolve their food by means of reagents. All are the grubs of flies and belong to the commonalty of the Muscidae. Many are their species. To distinguish them from one another by rearing them in order to obtain the perfect stage would involve a great expenditure of time to little profit. We will describe them by the general name of maggots.
To see them at work, I select, as the field of exploitation, the satanic bolete (Boletus Satanas, LENZ.), one of the largest mushrooms that I can gather in my neighborhood. It has a dirty-white cap; the mouths of the tubes are a bright orange-red; the stem swells into a bulb with a delicate network of carmine veins. I divide a perfectly sound specimen into equal parts and place these in two deep plates, put side by side. One of the halves is left as it is: it will act as a control, a term of comparison. The other half receives on the pores of its undersurface a couple of dozen maggots taken from a second bolete in full process of decomposition.
The dissolving action of the grub asserts itself on the very day whereon these preparations are made. The undersurface, originally a bright red, turns brown and runs in every direction into a mass of dark stalactites. Soon, the flesh of the cap is attacked and, in a few days, becomes a gruel similar to liquid asphalt. It is almost as fluid as water. In this broth the maggots wallow, wriggling their bodies and, from time to time, sticking the breathing holes in their sterns above the water. It is an exact repetition of what the liquefiers of meat, the grubs of the grey flesh fly and the bluebottle, have lately shown us. As for the second half of the bolete, the half which I did not colonize with vermin, it remains compact, the same as it was at the start, except that its appearance is a little withered by evaporation. The fluidity, therefore, is really and truly the work of the grubs and of them alone.
Does this liquefaction imply an easy change? One would think so at first, on seeing how quickly it is performed by the action of the grubs. Moreover, certain mushrooms, the coprini, liquefy spontaneously and turn into a black fluid. One of them bears the expressive name of the inky mushroom (Coprinus atramentarius, BULL.) and dissolves into ink of its own accord. The conversion, in certain cases, is singularly rapid. One day, I was drawing one of our prettiest coprini (Coprinus sterquilinus, FRIES), which comes out of a little purse or volva. My work was barely done, a couple of hours after gathering the fresh mushroom, when the model had disappeared, leaving nothing but a pool of ink upon the table. Had I procrastinated ever so little, I should not have had time to finish and I should have lost a rare and interesting find.
This does not mean that the other mushrooms, especially the boletes, are of ephemeral duration and lacking in consistency. I made the attempt with the edible bolete (Boletus edulis, BULL.), the famous cepe of our kitchens, so highly esteemed for its flavor. I was wondering whether it would not be possible to obtain from it a sort of Liebig's extract of fungus, which would be useful in cooking. With this purpose, I had some of these mushrooms cut into small pieces and boiled, on the one hand, in plain water and, on the other, in water with bicarbonate of soda added. The treatment lasted two whole days. The flesh of the bolete was indomitable. To attack it, I should have had to employ violent drugs, which were inadmissible in view of the result to be attained.
What prolonged boiling and the aid of bicarbonate of soda leave almost intact the fly's grubs quickly turn into fluid, even as the flesh worms fluidify hard-boiled white of egg. This is done in each instance without violence, probably by means of a special pepsin, which is not the same in both cases. The liquefier of meat has its own brand; the liquefier of the bolete has another sort. The plate, then, is filled with a dark, running gruel, not unlike tar in appearance. If we allow evaporation free course, the broth sets, into a hard, easily crumbled slab, something like toffee. Caught in this matrix, grubs and pupa perish, incapable of freeing themselves. Analytical chemistry has proved fatal to them. The conditions are quite different when the attack is delivered on the surface of the ground. Gradually absorbed by the soil, the excess of liquid disappears, leaving the colonists free. In my dishes, it collects indefinitely, killing the inhabitants when it dries up into a solid layer.