This section is from the book "Our Edible Toadstools and Mushrooms and How to Distinguish Them", by W. Hamilton Gibson. Also available from Amazon: Our Edible Toadstools And Mushrooms And How To Distinguish Them.
Before preparing mushrooms for the table, the specimens should be carefully scrutinized for a class of fungus specialists which we have not taken into account, and which have probably anticipated us. The mushroom is proverbial for its rapid development, but nature has not allowed it thus to escape the usual penalties of lush vegetation, as witness this swarming, squirming host, minute grubs, which occasionally honey-comb or hollow its entire substance ere it has reached its prime; indeed, in many cases, even before it has fully expanded or even protruded above ground.
Like the carrion-flies, the bees, and wasps, which in early times were believed to be of spontaneous origin - flies being generated from putrefaction, bees from dead bulls, and the martial wasps from defunct "war-horses" - these fungus swarms which so speedily reduce a fair specimen of a mushroom to a melting loathsome mass, were also supposed to be the natural progeny of the "poisonous toadstool." But science has solved the riddle of their mysterious omnipresence among the fungi, each particular swarm of grubs being the witness of a former visit of a maternal parent insect, which has sought the budding fungus in its haunts often before it has fully revealed itself to human gaze, and implanted within its substance her hundred or more eggs. To the uneducated eye these larvae all appear similar, but the specialist in entomology readily distinguishes between them as the young of this or that species of fly, gnat, or beetle.
As an illustration of the assiduity with which the history of these tiny scavenger insects has been followed by science, I may mention that in the gnat group alone over seven hundred species have been discovered and scientifically described, many of them requiring a powerful magnifier to reveal their identities.
Specimens of infected or decaying mushrooms preserved within a tightly closed box - and, we would suggest, duly quarantined - will at length reveal the imago forms of the voracious larvae: generally a swarm of tiny gnats or flies, with an occasional sprinkling of small glossy black beetles, or perhaps a beautiful indigo-blue insect half an inch in length, of most nervous habit, and possessed of a long and very active tail. This insect is an example of the curious group of rove-beetles - staphylinus - a family of insect scavengers, many of whose species depend upon the fungi for subsistence.
Even the large woody growth known as "punk" or "touchwood," so frequently seen upon decaying trunks, is not spared. A huge specimen in my keeping was literally reduced to dust by a single species of beetle.
Considering the prevalence of these fungus hosts, it is well in all mushrooms to take the precaution of making a vertical section through stem and cap, excluding such specimens as are conspicuously monopolized, and not being too critical of the rest, for the over-fastidious gourmet will often thus have little to show for his morning walk. I have gathered a hundred specimens of fungi in one stroll, perhaps not a quarter of which, upon careful scrutiny, though fair of exterior, would be fit for the table. The fungus - hunter par excellence has usually been there before us and left his mark (see page 135) - a mere fine brown streak or tunnel, perhaps, winding through the pulp or stem, where his minute fungoid identity is even yet secreted. But we bigger fungus-eaters gradually learn to accept him - if not too outrageously promiscuous - as a natural part and parcel of our Hachis aux Champignons, or our simple mushrooms on toast, even as we wink at the similar lively accessories which sophisticate our delectable raisins, prunes, and figs, to say nothing of prime old Rochefort!