Nov. i6, 1914 Apple Root Borer 181 



THE BURROWS 



The burrows of the apple root borer (PI. XXIX, figs, i, 2, and 3) are 

 of great length, that of a single larva often extending through the trunk 

 and roots for 5 or 6 feet and in some cases even 8 feet. Throughout its 

 length the burrow is packed with dustlike particles of wood that have 

 passed through the alimentary canal of the insect. Cross sections of the 

 burrows are oval in outhne, those of full-grown larvae being about i by 

 3 or 4 mm. in diameter. 



Except for the discoloration of the dustlike packing, time does not 

 change the appearance or form of the burrows in the wood until they are 

 obUterated by decay. Fresh burrows are usually found within half an 

 inch of the bark, and in large trees the position of a burrow in the wood 

 gives some clue to its age. In the large number of old trees cut and 

 examined during this investigation the finding of a large proportion of 

 the burrows comparatively near to the bark is taken as an indication that 

 this insect has been on the increase for the last 10 or 15 years. 



LIFE HISTORY OF APPLE ROOT BORER 

 THE KGG 



The eggs (PI. XXXI, fig. i) are somewhat variable in outline, an 

 average specimen being flattened, oblong, disklike, 1.3 by 1.9 mm. in 

 size. The surface is irregularly corrugated, the ridges and depressions 

 being more distinct near the margin. When first laid, the egg is white 

 or creamy white, but in a few days it changes to grayish brown, similar 

 to the bark in color, and resembling in a general way the shield of a small 

 scale insect. After the dark color is assumed, the embryo shows as a 

 whitish spot at the center of the egg. 



In the latitude of West Virginia the eggs are deposited in May and 

 June. They are glued tightly to the bark of the trunk a few inches above 

 the ground singly (PI. XXX, fig. 3, b) or, rarely, in pairs. They are 

 usually attached to a smooth surface, but are sometimes inserted into a 

 crack or beneath a scale of bark. When the lar\'^a hatches, it leaves the 

 egg from the underside and enters directly into the bark, thrusting its 

 castings backward into the discarded shell and so filling it that it retains 

 its normal size and shape. The abandoned shell often adheres to the 

 bark for a year or longer. 



THE LARVA 



The larva (PI. XXXI, fig. 2), before settling in the pupal chamber, is 

 long, slender, distinctly segmented, flattened, and of nearly uniform 

 width throughout, the first thoracic segment being slightly wider than 

 the others. Full-grown specimens average from 3 to 4 by 30 to 36 mm. 

 The color is white, except the small head and the anal forceps, which are 

 bro\vn. The anal forceps are prominent and shade from light brown at 

 the base to dark brown or black at the converging tips. After entering 

 the pupal cell, the lar\'a contracts to about half its former length and in 

 this condition (PI. XXXI, fig. 3) it remains during the second winter of 

 its Ufe in the tree. 



The larva lives in the tree for nearly two years, and during this time 

 its movements are substantially as follows: On leaving the egg it bores 



