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numerous old trees cut and examined during this investigation 

 the finding of a large proportion of the burrows comparatively near 

 the bark is taken as an indication that this insect has been on the 

 increase for the last 10 or 15 years. In the latitude of West Virginia, 

 oviposition occurs in May and June, the eggs being glued to the trunk 

 a few inches above the ground singly or, rarely, in pairs. On hatching, 

 the larva enters directly into the bark, thrusting its castings back- 

 wards 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 lives in the tree for nearly two years. 

 It first bores through to the cambium, thence through the cambium 

 down the trunk to the ground, whence it proceeds outwards along a 

 convenient root. It then burrows abruptly into the sohd wood, 

 where the remainder of the larval stage is spent. 



The larva often spends its first winter in a root not more than one- 

 sixteenth of an inch in diameter. It is active in autumn and in early 

 spring, probably to a considerable extent even in winter. In spring 

 it feeds rapidly back towards the base of the root and by midsummer 

 it has reached the centre of the root system and has begun to ascend 

 the body of the tree. The latter part of the summer and the autumn 

 are spent in boring upward through the trunk and in fashioning a 

 pupal chamber. In small trees, pupation takes place within 5 to 10 

 inches of the ground, but in larger ones the larvae ascend higher before 

 forming the pupal cell. In apple and pear trees about 6 inches in 

 diameter, it is not unusual for the larva to ascend 2 or 3 feet to pupate, 

 the ascent being made within half an inch of the inner bark. The 

 pupal chamber is a curved and enlarged terminus at the end of the 

 burrow, occupying a vertical position, with the convex side toward 

 the heart of the tree. The larva is not permanently settled in its 

 pupal cell until December, often after severe frost has occurred. The 

 adult beetle emerges in May, through a small round hole which it 

 gnaws in the bark. The only natural enemy known is the Ichneumon, 

 Xylophruridea agrili, Viereck, which attacks and destroys the larva 

 and pupa. One generation of the parasite appears early in spring 

 and another late in autumn. The female is believed to pierce the bark 

 and wood in order to reach the host. The spring brood oviposits 

 just before the root-borer larvae pupate and the autumn brood about 

 the time that the pupal cell is being formed. The parasitic larvae 

 attack their host externally, those from the spring brood developing 

 rapidly, and when full-grown, constructing cocoons which occupy 

 the host cell. This generation passes the greater part of the warm 

 season of the year as larvae in the cocoon. The autumn larvae 

 develop less rapidly, some not entering the cocoon until very early 

 in the spring. Many of the adult parasites die in endeavouring to 

 gnaw their way through the bark. The borers in small trees are the 

 most often parasitised, probably because they are more constantly 

 within reach of the ovipositor of the parasite. On the average, from 

 25 to 40 per cent, of the root-borers are destroyed by A', agrili. Artifi- 

 cial control measures must be directed toward the protection of the 

 trunk of the tree against the deposition of the egg, rather than by 

 killing the borer after it begins feeding. Where paints, washes or 

 mechanical devices of any kind are used on trees as a preventive of 

 injury by the round-headed apple-tree borer, equal protection may 



