APPLE-TRUNK BORER ITS BURROW. 



15 



This hole runs slightly inwards, towards the centre of the tree, 

 and then outwards, so that when it is completed its upper end is 

 perfi >rated through the sap-wood, and. is only covered, by the bark. 

 The lower flat portion of its burrow is by this 

 time stuffed in every part with its castings, 

 whilst the long cylindrical passage above is 

 still empty. As if fearful that these castings, 

 being so fine and dry, might sift out, and thus 

 leave an open passage for some marauding in- 

 sect or other enemy to crawl in and destroy it 

 during its defenceless pupa state, and that it 

 may, during this period of its life, be securely 

 held in- the middle of its cylindrical hole, the 

 worm now turns itself around, (as I think for 

 it is impossible to conjecture how otherwise 

 this long round cavity becomes filled in the 

 manner in which we usually find it,) and with 

 its jaws strips a quantity of woody fibres from 

 the inner walls of the middle part of its bur- 

 row, thus enlarging this part sufficiently to give 

 it ample room to repose here in its pupa state, 

 when its body becomes more short and broad 

 than it has previously been. With these fibres 

 of wood, which are from a half to three-fourths of an inch in 

 length, it firmly plugs up all the lower part of its burrow above 

 the flat excavation in the sap-wood, plach g the fibres frequently 

 in as regular order as the hairs of a mustache. And the castings 

 which it voids when in this inverted position are crowded, and 

 firmly packed together in the upper end of its burrow. Thus 

 the long cylindrical hole which it has bored becomes filled up, 

 and securely plugged with woody debris at each extremity, leav- 

 ing only a vacant space in its middle, where it is deepest sunk in 

 the wood of the tree, for the insect to lie during its pupa state. 

 The annexed cut will give an idea of these burrows and their 

 contents, as they appear when the bark is removed and the wood 

 cut away sufficiently to expose their whole length to view. 

 Having now finished its labors ana attained its growth it again 

 turns itself around to its former posture, with its head upwards, 



