16 APPLE-TRUNK BORER ITS BURROW. 



becomes inactive, and lies dormant during the winter season, and 

 the following spring is transformed to a pupa. From this pupa 

 the perfect insect soon after hatches, and tearing away the saw- 

 dust like powder which has been packed in the upper end of its 

 burrow, it has only to break through the bark here, which it 

 easily does with its sharp, powerful jaws, to come out of the tree. 



It will thus be seen that the burrow of this worm consists of 

 two distinct parts — a round flat excavation in the sap-wood, im- 

 mediately under the bark, and a long round hole in the solid 

 wood, running upwards from the upper part of the flat cavity, 

 first inwards towards the centre of the trunk, and then outwards 

 to the bark. This upper portion of the burrow is variable in its 

 length, being sometimes no more than an inch and three-quar- 

 ters, and at other times, as I am informed, a foot or more. The 

 lower flat portion as already stated, is about the size of a dollar, 

 but is frequently much larger than this; and when the worm 

 comes to knots or other obstructions when excavating it, instead 

 of making it round it is cut out in an irregular form. But in all 

 cases the worm passes the first periods of its life in consuming 

 the sap-wood, its jaws probably being too weak as yet to enable 

 it to work in the harder wood of the interior of the tree, and it 

 is by thus mining in the sap wood, and cutting off so many of 

 its vessels, that this worm does the chief injury to the tree, stint- 

 ing it in its growth, and causing the leaves to assume a yellowish, 

 sickly hue. And where four or five worms are at work in one 

 young tree, as is often the case, these flat cavities in the sap- 

 wood are liable to come in contact with each other, and thus 

 completely girdle and destroy the tree. 



Numerous variations in the form and direction of the burrows 

 of these borers may be met with. Some of the worms seem to be 

 very wild and erratic in their proceedings. It is sometimes the 

 case that as soon as it reaches the sap-wood it works directly up- 

 wards, under the bark, and then turns, it may be, obliquely 

 downwards before entering the heart-wood. A most singular de- 

 viation from the usual habit was related to me by Esquire Bald- 

 win, as follows : " The borer first made a flexuous channel up- 



