164 



HALF HOURS WITH INSECTS. [Packard. 



white bark beneath, as can easily be done without any injury 

 to the tree, wherever there is a j^oung worm it can easily be 

 detected. A little blackish spot, rather larger than a kernel 

 of wheat, will be discovered wherever an egg has been de- 

 posited, and by cutting slightly into the bark the worm will 

 be found. It gradually works its way onwards through the 

 bark, increasing in size as it advances, until it reaches the 

 sap-wood ; here it takes up its abode, feeding upon and con- 

 suming the soft wood, hereby forming a smooth, round, flat 

 cavity, the size of a dollar or larger, immediately under the 

 bark. It keeps its burrow clean by pushing its excrement 

 out of a small crevice or opening through the bark, which it 



Fig. 129. 



Apple Tree Borer. 



makes at the lower part of its burrow, and if this orifice 

 becomes clogged up it opens another. This excrement 

 resembles new fine sawdust, and enables us readily to de- 

 tect the presence of tlie worm by the little heap of this 

 substance which is accumulated on the ground, commonly 

 covering the hole out of which it is extruded, and by par- 

 ticles of it which adhere around the orifice when it is higher 

 up, or in the fork of the tree ; the outer surface of the bark 

 also often becomes slightly depressed, or flattened, over this 

 cavity." 



When half grown it sinks into the solid heart wood of the 

 tree and obliterates the flat cell, filling it up with its casting, 



4 



