11 



sible route. This, however, is a rather delicate operation, and requires the exertion of all 

 the insect's wonderful instinctive skill j for were it to gnaw too much of the wood away, 

 the branch would break during the proceeding, and probably crush the workman to death. 

 But with admirable forethought and precision, it leaves the bark and just enough woody 

 fibres untouched to sustain the branch until it has time to make good its retreat into its 

 burrow, the opening of which it carefully stops up with gnawed fragments of wood. 

 " But," as Dr. Fitch relates "the most astonishing part of this feat remains to be notice!. 

 The limb which he cuts off is sometimes oniy a foot in length, and is consequently quite 

 light ; sometimes ten feet long, laden with leaves, and quite heavy. "A man, by carefully 

 inspecting the length of the limb, the size of the branches, and the amount of the foliage 

 growing upon them, could judge how far it should be severed to insure its being after- 

 wards broken by the winds. But this worm is imprisoned in a dark cell, only an inch or 

 two long, in the interior of the limb. How is it possible for this creature, therefore, to 

 know the weight and length of the limb, and how far it should be cut asunder 1 A man, 

 moreover, on cutting a number of limbs of different lengths so far that they will be broken 

 by the winds, will find that he has often miscalculated, and that several of the limbs do 

 not break off' as he designed they should. This little worm, however, never makes a mis- 

 take of this kind. If the limb be short, it severs all the woody fibres, leaving it hanging 

 only by the bark ; if it be longer, a few of the woody fibres on the upper side are left un- 

 cut, in addition to the bark. If it be very long and heavy, not more than three-fourths of 

 the wood will be severed. With such consummate skill does this philosophical little car- 

 penter vary his proceedings to meet the circumstances of his situation in each particular 

 case ! " 



Having performed this operation carefully, and closed its hole, that the jarring of 

 the branch when it falls to the ground may not shake it out, the grub retreats to where 

 it first entered the limb, and goes on eating up through the heart for about six inches or 

 a foot, and this it does both before and after the branch reaches the ground. The object 

 of this amputating process it is difficult for us to understand f ully, but we may imagine 

 that it is for two purposes : first, as regards the insect itself, that it may the more effectu- 

 ally escape the attacks of woodpeckers and other foes, and be les3 exposed to the winter 

 frosts ; secondly, that the tree may receive the benefit of a pruning of its growth, which 

 in its natural state might be too exuberant. Thus wonderful and varied are the checks 

 and counter-checks that the Almighty imposes upon his works ; to each one there is laid 

 down the law, " Thus far shalt thou go, and no further ! " 



The obvious remedy for these singular insects, when they attack fruit or other valu- 

 able trees, is to gather up the fallen limbs and burn them, before the grub has time to 

 complete his transformation into the perfect state. 



6. The Apple Twig-borer (Bostrichus bicandatus, Say). — Besides the above mention- 

 ed insects, the branches, or rather twigs, of the apple-tree have as a foe a small cylindrical 

 beetle called the Twig-borer. It is frequently injurious in Illinois, Missouri and other 

 States, but has not yet made its appearance in Canada ; we shall therefore dismiss it in a 

 few words. "It preys upon the twigs of good sized trees, boring in just above a bud, 

 and working downwards through the pith in a cylindrical burrow for the space of one or 

 two inches. The male is distinguished from the female by having two little thorns pro- 

 jecting from the hind end of its body, and both males and females are found in these 

 burrows, and always with their heads downwards, showing that they bore the hole, not in 

 the larva state like other borers, but in the perfect beetle state. Neither can they bore 

 these holes as a breeding place for their future larva; ; for no larvse have ever been found 

 therein. Evidently, therefore, they must bore them as a means of supplying themselves 

 with food." — (Am. Ent., 1, 206.) Dr. Fitch states that chis insect occurs from Pennsyl- 

 vania to Mississippi, and has been common of late years in the orchards of Michigan and 

 Illinois ; We must not be surprised, then, to find it some day in the western parts of Ontario. 

 Mr. Zimmerman, of Cameron, Mo., states that they work during the months of A.ugust, 

 September and October, on both pear, cherry, and apple-trees ; and that he has found 

 •sometimes as many as ten twig-borers on a single two or three year old tree. The twigs 

 thus injured usually break off with the wind. 



