The More Important Apple Insects. 67 
Both the beetles and grubs or larvee burrow into the bark and slightly. into 
the wood, rapidly extending their burrows and destroying the vital part of the 
tree. On a tree that has been infested for some weeks the entrance and exit 
holes of the beetles may be so abundant as to suggest that the tree has been 
peppered with shot (fig. 184). This insect is of Huropean origin and is now 
widely distributed over the United States east of the Mississippi, and in numer- 
ous localities farther west. It attacks most pome and stone fruits, as well as 
mountain ash, chokecherry, June berry, wild plum, service berry, and perhaps 
other plants. 
During the winter season the fruit-tree barkbeetle is in the larva or grub 
stage within the larval galleries. The mature larve are whitish and are about 
three-sixteenths of an inch long. They pupate early in the spring and the 
beetles, which are about one-tenth of an inch in length and dark brown, emerge 
in late spring to early summer, according to the latitude. The females proceed 
to the trees and burrow through the 
bark until the sapwood is reached, 
where they make a round hole about 
the size of a pinhead. They then 
gnaw out a somewhat larger tunnel 
for a distance of about 2 inches par- 
allel with the grain of the wood. 
Along the sides of this brood cham- 
ber small cavities are made, into 
each of which an egg is placed. 
These eggs hatch in a few days and 
the larvee as they grow tunnel be- 
tween the bark and sapwood in a di- 
rection at right angles to the brood 
chambers to a distance of about 3 to 
4 inches. Upon attaining their full 
growth the larve pupate in cells just 
under the outer part of the sapwood. 
Shortly, through further transforma- ; : 
i 5 z Fic, 134.—Exit holes of fruit-tree bark- 
tion, the adults appear and cut their Waele. 
way out through the bark, making 
exit holes similar to those made by the females in entering the tree. In the 
North there are two generations a year, while in the South at least three and 
possibly four generations develop annually. 
To prevent injury by this insect great care should be taken to remove ali 
breeding places within or adjacent to the orchard. Sickly trees will harbor 
the fruit-tree barkbeetle and in this way large numbers of the pest will 
become established within the orchard. Cutting out and destroying infested 
trees and limbs and maintaining the trees in a thrifty condition will vastly 
reduce the injury of this pest. Where prunings are piled up and allowed to 
remain near orchards, the beetles often develop in numbers, attack more or 
less weakened trees, or even healthy trees, and by their repeated onslaughts 
do considerable harm, or eventually cause the trees to succumb. Thorough 
destruction of such prunings and weakened trees will usually correct such a 
situation, and the more or less healthy trees should be stimulated with 
a nitrogenous fertilizer, such as nitrate of soda, and cultivation. After a tree 
has once become infested there is no practical method of destroying the insects 
under the bark. A heavy application of whitewash in the spring just before the 
beetles begin their attack will act as a moderate preventive. 
