INSECTS AFFECTING PARK AND WOODLAND TREES 85 



Life history. 'I'lu- life history of this insect may be summarized as 

 follows. The )ouno- l)orer on the approach of winter, descends as near the 

 ground as its nailery will allow and remains inactive till the following spring, 

 when it renews operations, and on the approach of the second winter it is 

 abt)ut half grown and still livini,'- in the sapwood. The most damage is 

 done at this period, because where four or five occur in a single tree they 

 almost girdle it. The ne.xt summer, when it has become 

 about three fourths grown, it cuts a cylindric passage 

 upward into the solid wood and having completed its 

 larval growth, continues this passage to the bark, some- 

 times cutting entirely through a tree to the opposite 

 side and occasionally turning back at a different angle. 



Fig. 10 Round-headed apple 



The injury is so severe that several borers in a tree borer, beetle 



may fairly riddle its base. The upper end of the gallery is stuffed with 

 fine borings and the lower part filled with long wood fibers. The larva 

 remains unchanged in this cell through the winter, transforming to a pupa 

 the following spring, and the beetle appears sometime during the sum- 

 mer, escaping through a circular exit hole. 



Distribution. This species is a common pest in southern Canada and 

 the Eastern, Middle and Western States. It does not appear to have been 

 listed from the Pacific slope. 



Description. The beetle is about 3^^ inch long and may be easily 

 recoo-nized by its brownish color with two white bands joined at the front 

 and extending to the tip of the wing covers. The underside and front of 

 the head, white, and the antennae are light gray with legs lighter. 



Natural enemies. A small parasite known as C e n o c o e 1 i u s p o p u- 

 1 a t o r Say, has been reared from this insect, and the downy woodpecker 

 and the great golden woodpecker have been observed in infested orchards. 

 These two birds and probably others are undoubtedly of considerable 

 value in destro)ing the grubs of this pernicious borer. 



Remedial measures. These are practicable only in the case of highly 



