Returning to the rotten logs for another grub-filled fragment, I paused to watch some wasps that, like the birds, were feasting upon these grubs. A wasp on finding a grub simply thrust his snout into the grub and then braced himself firmly as he bored down and proceeded to suck his victim's fluids. In throwing a log to one side I disturbed a bevy of slender banqueters that I had not seen. Instantly a number of wasps were effervescing round my head. Despite busy arms, they effectively peppered my face, and I fled to a neighboring brook to bathe my wounds.
While I was at a safe distance, cogitating as to the wisdom of returning for further examination of the logs, a black bear appeared down the opening. From his actions I realized that he had scented not myself but the feast in the log-pile. After sniffling, pointing, and tip-toeing, he lumbered toward the logs. Of course I was curious as to the manner of his reception and allowed him to go unwarned to the feast. Two Rocky Mountain jays gave a low, indifferent call on his approach, but the other birds ignored his coming. With his fore paw he tore a log apart and deftly picked up a number of grubs. All went well until he climbed upon the pile of wreckage and rolled a broken log off the top. This disturbed another wasp feast. Suddenly he grabbed his nose with both fore paws and tumbled off the pile. For a few seconds he was slapping and battling at a lively pace; then, with a woof-f-f-f! he fled—straight at me. I made a tangential move.
The hardwoods are also warred upon by bugs, weevils, borers, and fungi. The percentage of swift deaths, however, that the insects cause among the hardwoods is much smaller than that among the pines; but the percentage of diseased and slow-dying hardwoods is much greater. The methods of beetles that attack oaks, hickories, aspens, and birches are similar to the methods of those that attack pines and spruces. They attack in swarms, bore through the bark, and deposit their eggs either in the inner bark or in the cambium,—the vitals of the tree. The grubs, on hatching, begin to feed upon the tree's vitals. In this feeding each grub commonly drives a minute tunnel from one to several inches in length. Where scores of grubs hatch side by side they drive a score of closely parallel tunnels. Commonly these are either horizontal or vertical and generally they are numerous enough to make many complete girdles around the tree. Girdling means cutting off the circulation, and this produces quick death.
While these beetles are busy killing unnumbered millions of trees annually, the various species of another group of beetles known as weevils are active in deforming and injuring even a greater number. They mutilate and deform trees by the millions. The work of the white-pine weevil is particularly devilish. It deposits its eggs in the vigorous shoots of the white-pine sapling. The eggs hatch, and the grubs feed upon and kill the shoot. Another shoot bursts forth to take the place of the one killed; this is attacked and either killed or injured. The result is a stunted, crooked, and much-forked tree.
Borers attack trees both old and young of many species, and a few of these species with wholesale deadly effect. Birches by the million annually fall a prey to these tree-tunnelers, and their deadly work has almost wiped the black locust out of existence. Borers pierce and honeycomb the tree-trunk. If their work is not fatal, it is speedily extended and made so by the fungi and rot that its holes admit into the tree.
Trees, like people, often entertain a number of troubles at once and have misfortunes in series. A seedling injured by one insect is more likely to be attacked again, and by some other insect, than is the sound seedling by its side. Let a seedling be injured, and relays of insects—often several species at a time and each species with a way of its own—will attack it through the seedling, sapling, pole, tree, and veteran stages of its growth until it succumbs. Or let a vigorous tree meet with an accident, and like an injured deer it becomes food for an enemy. If lightning, wind, or sleet split the bark or break a limb, through these wounds some spore or borer will speedily reach the tree's vitals. In many cases the deadly work of parasitic plants and fungi is interrelated with, and almost inseparable from, the destructive operations of predacious insects. Many so-called tree diseases are but the spread of rot and fungi through the wood by means of an entrance bored by a borer, weevil, or beetle.
The bark of a tree, like the skin on one's body, is an impervious, elastic armor that protects blood and tissues from the poisonous or corrupting touch or seizure of thousands of deadly and incessantly clamoring germs. Tear the skin on one's body or the bark upon a tree, and eternally vigilant microbes at once sow the wound with the seeds of destruction or decay. A single thoughtless stroke of an axe in the bark of a tree may admit germs that will produce a kind of blood-poisoning and cause slow death.
A TREE KILLED BY MISTLETOE AND BEETLES
The false-tinder fungus apparently can spread and do damage only as it is admitted into the tree through insect-holes or the wounds of accidents. Yet its annual damage is almost beyond computation. This rot is widely distributed and affects a large number of species. As with insects, its outbreaks often occur and extend over wide areas upon which its depredations are almost complete. As almost all trees are susceptible to this punk-producer, it will not be easy to suppress.