the Value of Birds to Man. 101 



Well-being of the tree, but the tree is necessary to the life o£ 

 the bird. 



Consider for a moment the life of a tree in connection 

 with the insects that prey upon it. At the very beginning, 

 before the seed or nut has germinated, it may be entered by 

 a grub which destroys it. Should, however, the seed or nut 

 be permitted to gfow, the roots of the seedling may bo 

 attacked by beetles. Escaping this danger, a worm lays its 

 eggs in the cracks of the bark. On hatching, the worm^ or 

 borer, perforates a hole in the stem. This hole, admitting 

 water from every passing shower, causes a decay in the 

 wood to commence, from which the tree may never recover. 

 Other borers feed upon the bark, eating the soft inner layer 

 and the sap. The twigs are affected by the larva) of certain 

 beetles, which act as girdlers, sometimes destroying limbs 

 over an inch in diameter. Weevils bore under the bark and 

 into the pith, making excavations in which the eggs are laid. 

 For the same purpose the cicada makes a terrible wound, 

 which often proves fatal. The limbs of trees arc affected by 

 aphides, which puncture them and feed upon their juices, 

 exhausting the sap. Many species of plant-lice and scale- 

 insects infest trees, doing great damage ; while over 100 

 different species of gall-flies are parasitic upon them. The 

 buds of trees are entered and destroyed by the larvae of 

 certain moths, while the leaves are devoured by caterpillarsi 

 To take the oak as an example, it is known that altogether 

 over 500 species of insects prey upon it. Finally, bo it 

 remembered that in the bark and the underlying tissues 

 lie the vital energies of a tree. 



It is difficult to perceive the usefulness of these insects 

 which feed on the different parts of the tree, though they 

 may, perhaps, when in normal numbers, exert a useful 

 influence by a healthful and necessary pruning. It is 

 certain, however, that if they were not in turn preyed upon 

 by birds, they would so increase in numbers, that the tree 

 could not survive the injuries they would inflict. 



I spent the formative period of my years in, or in close 

 proximity to, primeval forests, and going often to Nature's 



