INSECTS ATTACKING THE PEAR, AND THEIR CONTROL 1021 



hatching, which occurs about the first of July, the young larva 

 burrows directly from the egg to the sapwood, where it cuts an 

 irregular serpentine mine that is very characteristic and easily 

 distinguishable from the work of other borers attacking pear trees. 

 The in nl ling of the bark kills the trees or weakens them so that 

 they lapse into a languishing state and become unproductive. 



'/'rrd/mciil. Wood-boring insects are generally difficult pests to 

 combat, and this beetle in particular presents a series of difficul- 

 ties not usually encountered in a single species. For small trees 

 perhaps the most satisfactory method of control is to cut into the 

 mine of the insect and destroy the inmate. The course of the 

 mine cun usually be traced by the discoloration and splitting of 

 the bark following the tunneling by the borer. Recent studies 

 have shown that the beetles feed readily on the foliage, and they 

 point to the possibility of successfully controlling the insect by 

 an application of an arsenical spray during the latter part of May, 

 or shortly before the beetles begin to appear. Worthy also of 

 trial during early June is an applica- 

 tion of a deterrent wash to the trunks 

 and branches in order to prevent ovi- 

 position. For bearing orchards the 

 latter measures are recommended tenta- 

 tively, pending the results of our ex- 

 periments to determine their merits. 



The Round- and Flat-headed Borers 

 The round-headed borer, Saperda 

 Candida Fab., and the flat-headed borer, 

 Ehrysobothris femorata Fab., are very 

 destructive pests to different fruit trees, 

 including the pear, and they do more 

 damage than the average grower ap- 

 preciates. The injuries are caused by 

 the grubs, or larvae, that work beneath 

 the bark. If the burrows or channels 

 of the insects are numerous, the bark 

 may be girdled, resulting in the decline 

 and death of the trees. Recent investi- 



FIG. 302. THE ROUND- 

 HEADED APPLE-TREE 

 BORER 



