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Who's your family doctor; your tree doctor, I mean? The reason I ask is that, when we got back from our hike yesterday, I noticed something suspicious in the bark of one of those two fine old Elms in your front yard, near what I suppose used to be the front gate, in the days of picket fences. I've seen many a dear old couple like that in both Old and New England. In one instance, I remember, they were known as "Grandfather and Grandmother Elm." They were set out by the grandfather of the present owner when he first came to the place with his bride; and, like Philemon and Baucis, of the old Greek story, they continued, through all the years, to offer a hospitable welcome to the stranger. "AN ENEMY HATH DONE THIS!" Now, here's the suspicious thing I refer to: see those little "shot-holes" in the bark? Well, they aren't shot-holes at all. Let me take that trusty blade of yours a moment and I'll show you. The holes, you notice, open into little tunnels. As we follow these tunnels up, we find they keep getting broader and end in a chamber, right under one of those holes in the bark. The secret of it is this: Beginning as early as May, and on into August, Elms are visited by gray, long-horned beetles with red lines and black spots on their jackets. These beetles lay eggs on the bark. The eggs hatch into tiny, round-headed grubs which promptly tunnel through to the cambium layer of the tree and keep eating their way along until they are fully grown. Then they cut out a bed-chamber beneath the bark and each of them changes to what looks like the mummy of a beetle. Along in May this "mummy" actually does what the Egyptians thought their mummied dead would do some fine day. It comes back to life! A very live and busy beetle bores its way out through the bark and starts into the lumber business on its own account. The tunnels keep getting broader, as the grub grows, until they end in this rebirth chamber. This enlargement of the chamber to accommodate the growth of the grub is due to the fact that his jaws grow in proportion; a fine piece of engineering -- from an Elm-borer's standpoint! But not from our standpoint. When a limb or the trunk of a tree is girdled by the burrows of these beetles its doom is sealed. Different species of bark-beetles attack different kinds of trees and they each make their own style of tunnel. These and other workers on the bodies and leaves of trees leave marks as characteristic as the thumb-marks in the criminal identification records of the police (It has taken years of observation on the part of the skilled men at Washington, and in the various state agricultural experiment stations, to learn the habits of these insects; and yet you can have the benefit of the result of all this good work, for the protection of your own trees, simply by asking for pamphlets on the subject. I am giving some of this information here that you may see how interesting it is.) In the case of the bark-borers, where a tree has been attacked, a thorough search of the trunk and dying branches will show patches of dead bark that peel off easily. Underneath you'll find the tunnels and, if they're still at home, the round-headed grubs. SPARTANS SOMETIMES, THESE MOTHER-TREES! Another sign of trouble is when the leaves at the top of the tree or on the ends of the branches turn brown or fall, even without turning brown. This occurs when the injury done by the insects is such as to interfere with the proper flow of sap. Then the mother-tree, should the conditions of living become too hard, plays the Spartan, deliberately shutting off the supply of sap to the youngest twigs and leaves! This is particularly noticeable in rapidly growing trees, like the Poplars and Willows. In their spring enthusiasm, when the sap is flowing freely, they sometimes send out more twigs and leaves then they can support when the hard times come. Then, by the formation of cork rings, similar to those made by all trees when they get ready to part with their leaves in the fall, the life-giving sap is gradually cut off and these twigs and leaves drop. But, by whatever sign you detect them, the presence of the borers and other insect enemies of trees is a very serious matter; and even a small boy who can't do anything else about it, himself, may be of immense service, not only to his home trees, but to the trees of a whole neighborhood, by keeping a sharp lookout. Trees that are not as vigorous as they might be, for lack of proper soil, or necessary fertilization, or that have been weakened by wounds on the bark or by fungous growths, are particularly subject to attacks by borers. |
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