60 
‘ 
Farmers’ Bulletin 1169. 
Seasonal history and habits.—The borer itself (fig. 40, ¢), 1. e., the 
stage of the insect mainly responsible for the damage, is a slender, 
Fig. 39.—Work of 
bronze birch 
borer on limb of 
white birch. 
Somewhat re- 
duced. (Chitten- 
den. ) 
flattened, footless, creamy white grub, about three- 
fourths inch long when full grown, which transforms 
to a small, slender, olive-bronze, winged beetle (fig. 
40, a) nearly one-half inch in length. This beetle 
emerges from the trees in May or early June, de- 
pending on the location and season, and the female 
deposits her eggs in crevices on rough surfaces of 
the bark, several together. These eggs hatch into 
tiny grubs which burrow their way through the 
bark, underneath which they tunnel a zigzag course 
in the bark and sapwood until they are full grown. 
In the autumn they excavate a chamber in the wood 
or outer bark and here spend the winter. About 
April or May the following spring they transform 
to pupe, and these into the adults which gnaw their 
way out, leaving peculiar 
oval holes in the bark. 
Their life cycle is thus 
completed within a year. 
The beetle attacks birch, 
poplar, and aspen trees 
wherever they grow in 
the United States, being 
particularly destructive 
to imported birch in 
parks and lawns in the 
Northern States and at- 
tacking from slender 
branches to trunks of 
trees over 25 years old. 
Prevention of damage, 
and control.— Badly 
damaged trees are not 
only past saving but are 
a menace to the trees of Fria. 40.—Bronze birch borer: 
a, Female beetie; b, first 
the neighborhood still alhdorninad: seam ei teei arate 
free from attack; there- from below; ¢, larva from 
5 above. <All enlarged about 
fore trees showing dead 84. tines Hae ee aie 
tops and other evidences beetle shows natural length. 
‘ " (Chittenden. 
of infestation should be : 
cut down and burned during autumn or winter and not later than 
May 1. A tree cut here and there will not check the ravages of 
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