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 succ.u.mbs. 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.

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.

[Ill.u.s.tration: A TREE KILLED BY MISTLETOE AND BEETLES]

The study of forest insects has not progressed far enough to enable one to make more than a rough approximation of the number of the important species that attack our common trees. However, more than five hundred species are known to afflict the st.u.r.dy oak, while four hundred prey upon the bending willow. The birches supply food to about three hundred of these predacious fellows, while poplars feed and shelter almost as many. The pines and spruces are compelled permanently to pension or provide for about three hundred families of sucking, chewing parasites.

The recent ravages of the chestnut-tree blight and the appalling depredations of the gypsy and brown-tailed moths, together with other evils, suggest at once the bigness of these problems and the importance of their study and solution. The insect army is as innumerable as the leaves in the forest. This army occupies points of vantage in every part of the tree zone, has an insatiable appet.i.te, is eternally vigilant for invasion, and is eager to multiply. It maintains incessant warfare against the forest, and every tree that matures must run a gantlet of enemies in series, each species of which is armed with weapons long specialized for the tree's destruction.

Some trees escape unscarred, though countless numbers are killed and mult.i.tudes maimed, which for a time live almost useless lives, ever ready to spread insects and disease among the healthy trees.

Every part of the tree suffers; even its roots are cut to pieces and consumed. Caterpillars, grubs, and beetles specialize on defoliation and feed upon the leaves, the lungs of the trees. The partial defoliation of the tree is devitalizing, and the loss of all its leaves commonly kills it. Not only is the tree itself attacked but also its efforts toward reproduction. The dainty bloom is food for a number of insect beasts, while the seed is fed upon and made an egg-depository by other enemies. Weevils, blight, gall, ants, aphids, and lice prey upon it. The seed drops upon the earth into another army that is hungry and waiting to devour it. The moment it sprouts it is gnawed, stung, bitten, and bored by ever-active fiends.

Many forest trees are scarred in the base by ground fires. These trees are entered by insects through the scars and become sources of rot and insect infection. Although these trees may for a time live on, it is with a rotten heart or as a mere hollow sh.e.l.l. A forest fire that sweeps raging through the tree-tops has a very different effect: the twigs and bark are burned off and the pitches are boiled through the exterior of the trunk and the wood fortified against all sources of decay. This preservative treatment often gives long endurance to fire-killed timber, especially when the trees killed are yellow pine or Douglas spruce. Many a night in the Rocky Mountains my eager, blazing camp-fire was burning timber that forest fires had killed forty and even sixty years before.

In forest protection and improvement the insect factor is one that will not easily down. Controlling the depredations of beetles, borers, weevils, and fungi calls for work of magnitude, but work that insures success. This work consists of the constant removal of both the infected trees and the dwarfed or injured ones that are susceptible to infection. Most forest insects multiply with amazing rapidity; some mother bark-beetles may have half a million descendants in less than two years. Thus efforts for the control of insect outbreaks should begin at once,--in the early stages of their activity. A single infested tree may in a year or two spread destruction through thousands of acres of forest.

Most insects have enemies to bite them. The ichneumon-fly spreads death among injurious grubs. Efforts to control forest-enemies will embrace the giving of aid and comfort to those insects that prey upon them. Bugs will be hunted with bugs. Already the gypsy moth in the East is being fought in this way. Many species of birds feed freely upon weevils, borers, and beetles. Of these birds, the woodp.e.c.k.e.rs are the most important. They must be protected and encouraged.

There are other methods of fighting the enemy. A striking and successful device for putting an end to the spruce-destroying beetle is to hack-girdle a spruce here and there in the forest at a season when the physiological make-up of the tree will cause it to change into a condition most favorable for the attraction of beetles. Like carrion, this changed condition appears to be scented from all quarters and afar. Swarms of beetles concentrate their attack upon this tree and bury themselves in it and deposit their eggs. The multiplied army will remain in the tree until late spring. Thus months of time may be had to cut and burn the tree, with its myriads of murderous guests. The freedom of the big trees from insect attacks suggests that man as well as nature may develop or breed species of trees that will better resist or even defy insects.

Insects are now damaging our forests to the extent of not less than one hundred million dollars annually. This we believe to be a conservative estimate. Yet these figures only begin to tell the story of loss. They tell only the commercial value of the timber. The other greater and higher values cannot be resolved into figures. Forest influences and forest scenes add much to existence and bestow blessings upon life that cannot be measured by gold.

Dr. Woodp.e.c.k.e.r, Tree-Surgeon

Dr. Woodp.e.c.k.e.r, Tree-Surgeon

Although the eagle has the emblematic place of honor in the United States, the downy woodp.e.c.k.e.r is distinguished as the most useful bird citizen. Of the eight hundred and three kinds of birds in North America, his services are most helpful to man. He destroys destructive forest insects. Long ago Nature selected the woodp.e.c.k.e.r to be the chief caretaker--the physician and surgeon--of the tree world. This is a stupendous task. Forests are extensive and are formed of hundreds of species of trees. The American woodp.e.c.k.e.rs have the supervision of uncounted acres that are forested with more than six hundred kinds of trees.

With the exception of the California big tree, each tree species is preyed upon by scores, and many species by hundreds, of injurious and deadly insects. Five hundred kinds of insects are known to prey upon the oak, and a complete count may show a thousand kinds. Many of these insects multiply with amazing rapidity, and at all times countless numbers of these aggressive pests form warrior armies with which the woodp.e.c.k.e.r must constantly contend.

In this incessant struggle with insects the woodp.e.c.k.e.r has helpful a.s.sistance from many other bird families. Though the woodp.e.c.k.e.r gives general attention to hundreds of kinds of insects, he specializes on those which injure the tree internally,--which require a surgical operation to obtain. He is a distinguished specialist; the instruments for tree-surgery are intrusted to his keeping, and with these he each year performs innumerable successful surgical operations upon our friends the trees.

Woodp.e.c.k.e.rs are as widely distributed as forests,--just how many to the square mile no one knows. Some localities are blessed with a goodly number, made up of representatives from three or four of our twenty-four woodp.e.c.k.e.r species. Forest, shade, and orchard trees receive their impartial attention. The annual saving from their service is enormous. Although this cannot be estimated, it can hardly be overstated.

A single borer may kill a tree; so, too, may a few beetles; while a small number of weevils will injure and stunt a tree so that it is left an easy victim for other insects. Borers, beetles, and weevils are among the worst enemies of trees. They multiply with astounding rapidity and annually kill millions of scattered trees. Annually, too, there are numerous outbreaks of beetles, whose depredations extend over hundreds and occasionally over thousands of acres. Caterpillars, moths, and saw-flies are exceedingly injurious tree-pests, but they damage the outer parts of the tree. Both they and their eggs are easily accessible to many kinds of birds, including the woodp.e.c.k.e.rs; but borers, beetles, and weevils live and deposit their eggs in the very vitals of the tree. In the tree's vitals, protected by a heavy barrier of wood or bark, they are secure from the beaks and claws of all birds except Dr. Woodp.e.c.k.e.r, the chief surgeon of the forest.

About the only opportunity that other birds have to feed upon borers and beetles is during the brief time they occupy in emerging from the tree that they have killed, in their flight to some live tree, and during their brief exposure while boring into it.

Beetles live and move in swarms, and, according to their numbers, concentrate their attack upon a single tree or upon many trees. Most beetles are one of a dozen species of _Dendroctonus_, which means "tree-killer." Left in undisturbed possession of a tree, many mother beetles may have half a million descendants in a single season.

Fortunately for the forest, Dr. Woodp.e.c.k.e.r, during his ceaseless round of inspection and service, generally discovers infested trees. If one woodp.e.c.k.e.r is not equal to the situation, many are concentrated at this insect-breeding place; and here they remain until the last dweller in darkness is reached and devoured. Thus most beetle outbreaks are prevented. Now and then all the conditions are favorable for the beetles, or the woodp.e.c.k.e.r may be persecuted and lose some of his family; so that, despite his utmost efforts, he fails to make the rounds of his forest, and the result is an outbreak of insects, with wide depredations. So important are these birds that the shooting of a single one may allow insects to multiply and waste acres of forest.

During the periods in which the insects are held in check the woodp.e.c.k.e.r ranges through the forest, inspecting tree after tree. Many times, during their tireless rounds of search and inspection, I have followed them for hours. On one occasion in the mountains of Colorado I followed a Batchelder woodp.e.c.k.e.r through a spruce forest all day long. Both of us had a busy day. He inspected eight hundred and twenty-seven trees, most of which were spruce or lodge-pole pine.

Although he moved quickly, he was intensely concentrated, was systematic, and apparently did the inspection carefully. The forest was a healthy one and harbored only straggling insects. Now and then he picked up an isolated insect from a limb or took an egg-cl.u.s.ter from a break in the bark on a trunk. Only two pecking operations were required. On another occasion I watched a hairy woodp.e.c.k.e.r spend more than three days upon one tree-trunk; this he pecked full of holes and from its vitals he dragged more than a gross of devouring grubs. In this case not only was the beetle colony destroyed but the tree survived.

Woodp.e.c.k.e.r holes commonly are shallow, except in dead trees. Most of the burrowing or boring insects which infest living trees work in the outermost sapwood, just beneath the bark, or in the inner bark. Hence the doctor does not need to cut deeply. In most cases his peckings in the wood are so shallow that no scar or record is found. Hence a tree might be operated on by him a dozen times in a season, and still not show a scar when split or sawed into pieces. Most of his peckings simply penetrate the bark, and on living trees this epidermis scales off; thus in a short time all traces of his feast-getting are obliterated. I have, however, in dissecting and studying fallen trees, found a number of deep holes in their trunks which woodp.e.c.k.e.rs had made years before the trees came to their death. In one instance, as I have related in "The Story of a Thousand-Year Pine" in "Wild Life on the Rockies," a deep oblong hole was pecked in a pine nearly eight hundred years before it died. The hole filled with pitch and was overgrown with bark and wood.

[Ill.u.s.tration: WOODp.e.c.k.e.r HOLES IN A PINE INJURED BY LIGHTNING]

Woodp.e.c.k.e.rs commonly nest in a dead limb or trunk, a number of feet from the ground. Here, in the heart of things, they excavate a moderately roomy nest. It is common for many woodp.e.c.k.e.rs to peck out a deep hole in a dead tree for individual shelter during the winter.

Generally neither nest nor winter lodging is used longer than a season. The abandoned holes are welcomed as shelters and nesting-places by many birds that prefer wooden-walled houses but cannot themselves construct them. Chickadees and bluebirds often nest in them. Screech owls frequently philosophize within these retreats.

On bitter cold nights these holes shelter and save birds of many species. One autumn day, while watching beneath a pine, I saw fifteen brown nuthatches issue from a woodp.e.c.k.e.r's hole in a dead limb. Just what they were doing inside I cannot imagine; the extraordinary number that had gathered therein made the incident so unusual that for a long time I hesitated to tell it. However, early one autumn, Mr. Frank M. Chapman climbed up the mountainside to see me, and, while resting on the way up, he beheld twenty-seven nuthatches emerge from a hole in a pine.

By tapping against dead tree-trunks I have often roused Mother Woodp.e.c.k.e.r from her nest. Thrusting out her head from a hole far above, she peered down with one eye and comically tilted her head to discover the cause of the disturbance. With long nose and head tilted to one side, she had both a storky and a philosophical appearance. The woodp.e.c.k.e.r, more than any other bird of my acquaintance, at times actually appears to need only a pair of spectacles upon his nose in order fully to complete his att.i.tude and expression of wisdom.

The downy woodp.e.c.k.e.r, the smallest member of a family of twenty-four distinguished species, is the honored one. He is a confiding little fellow and I have often accompanied him on his daily rounds. He does not confine his attacks to the concealed enemies of the trees, but preys freely upon caterpillars and other enemies which feast upon their leaves and bloom. He appears most content close to the haunts of man and spends much of his time caring for orchards and cleaning up the shade trees. One morning in Missouri a downy alighted against the base of an apple tree within a few feet of where I was standing. He arrived with an undulating flight and swept in sideways toward the trunk, as though thrown. Spat! he struck. For a moment he stuck motionless, then he began to sidle round and up the trunk. Every now and then he tapped with his bill or else stopped to peer into a bark-cavity. He devoured an insect egg-cl.u.s.ter, a spider, and a beetle of some kind before ascending to the first limb.

Just below the point of a limb's attachment he edged about, giving the tree-trunk a rattling patter of taps with his bill. He was sounding for something. Presently a spot appeared to satisfy him. Adjusting himself, he rained blows with his pick-axe bill upon this, tilting his head and directing the strokes with an apparently automatic action, now and then giving a side swipe with his bill, probably to tear out a splinter or throw off a chip. In six minutes his prey was evidently in sight. Then he enlarged the hole and slightly deepened it vertically. Pausing, he thrust his head into the hole and his bill into a cavity beyond. With a backward tug he pulled his head out, then his bill, and at last his extended tongue with a grub impaled on its barbed point. This grub was dragged from the bottom of a crooked gallery at a point more than three inches beyond the bottom of the pecked hole. A useful bread-getting tool, this tongue of his,--a flexible, extensible spear.

In another tree he uncovered a feast of ants and their eggs. Once a gra.s.shopper alighted against another tree-trunk up which he was climbing. Downy seized him instantly. In one tree-top he consumed an entire tent-caterpillar colony. In four hours he examined the trunks, larger limbs, and many of the smaller ones of one hundred and thirty-eight apple trees. In this time he made twenty-two excavations, five of which were large ones. Among the insects devoured were beetles, ants, their eggs and their aphids, a gra.s.shopper, a moth or two, and a colony of caterpillars. I followed him closely, and frequently was within a few feet of him. Often I saw his eyes, or rather one eye at a time; and a number of times I imagined him about to look round and with merry laugh fly away, for he frequently acted like a happy child who is closely watching you while all the time merrily pretending not to see you. Yet, in all those four hours, he did not do a single thing which showed that he knew of my nearness or even of my existence!

Examining each tree in turn, he moved down a long row and at the end flew without the slightest pause to the first tree in the next row.

From here he examined a line of trees diagonally across the orchard to the farther corner. Here he followed along the outside row until he flew away. The line of his inspection, from the time I first saw him until he flew away, formed a big letter "N."

During a wind-storm in a pine forest a dead tree fell near me and a flying limb knocked a downy, stunned, to the earth, by my feet. On reviving in my hands, he showed but little excitement, and when my hands opened he pushed himself off as though to dive to the earth; but he skimmed and swung upward, landing against a tree-trunk about twenty feet distant. Up this he at once began to skate and sidle, exploring away as though nothing had happened and I were only a stump.

Little Boy Grizzly

Little Boy Grizzly

One day, while wandering in the pine woods on the slope of Mt. Meeker, I came upon two young grizzly bears. Though they dodged about as lively as chickens, I at last cornered them in a penlike pocket of fallen trees.

Getting them into a sack was one of the liveliest experiences I ever had. Though small and almost starved, these little orphans proceeded to "chew me up" after the manner of big grizzlies, as is told of them in books. After an exciting chase and tussle, I would catch one and thrust him into the sack. In resisting, he would insert his claws into my clothes, or thrust them through the side of the sack; then, while I was trying to tear him loose, or to thrust him forcibly in, he would lay hold of a finger, or take a bite in my leg. Whenever he bit, I at once dropped him, and then all began over again.

Their mother had been killed a few days before I found them; so, of course, they were famished and in need of a home; but so bitterly did they resist my efforts that I barely succeeded in taking them. Though hardly so large as a collie when he is at his prettiest, they were nimble athletes.

At last I started home, the sack over my shoulder, with these lively _Ursus horribilis_ in the bottom of it. Their final demonstration was not needed to convince me of the extraordinary power of their jaws.

Nevertheless, while going down a steep slope, one managed to bite into my back through sack and clothes, so effectively that I responded with a yell. Then I fastened the sack at the end of a long pole, which I carried across my shoulder, and I was able to travel the remainder of the distance to my cabin without another attack in the rear.

Of course the youngsters did not need to be taught to eat. I simply pushed their noses down into a basin of milk, and the little red tongues at once began to ply; then raw eggs and bread were dropped into the basin. There was no hesitation between courses; they simply gobbled the food as long as I kept it before them.

Jenny and Johnny were pets before sundown. Though both were alert, Johnny was the wiser and the more cheerful of the two. He took training as readily as a collie or shepherd-dog, and I have never seen any dog more playful. All bears are keen of wit, but he was the brightest one of the wild folk that I have ever known. He grew rapidly, and ate me almost out of supplies. We were intimate friends in less than a month, and I spent much time playing and talking with him. One of the first things I taught him was, when hungry, to stand erect with arms extended almost horizontally, with palms forward. I also taught him to greet me in this manner.