as the trees continue to weaken. There is a 2-year life cycle in the 
North; in the South only one year is required. 
Control under forested conditions is usually impracticable ex- 
cept for such management practices as are helpful in maintaining 
or promoting tree vigor. The watering or fertilizing of valuable 
shade trees should be helpful in protecting them from attack. 
The bronze birch borer, Agrilus anxius Gory, apparently occurs 
throughout most of the range of birch in Canada and the United 
States. It breeds in various birches, paper and yellow being pre- 
ferred. The adult is deep green-bronze and about the same size 
and shape as the adult of the two-lined chestnut borer. There are 
coppery reflections on the front of the pronotum; the front of the 
head is greenish in the male and copper-bronze in the female. 
Full-grown larvae are slender, flattened, about 25 mm. long, and 
have two spines at the posterior end. 
Adults begin to emerge in late May or early June and continue 
until August, depending on locality, and they feed on leaves for 
about three weeks before egg laying begins. Eggs are deposited 
singly or in small groups beneath loose flakes of bark and in 
COURTESY OF DUKE UNIV. SCH. OF 
FOREST. 
FIGURE 47.—Galleries of the 
two-lined chestnut borer. 
Agrilus bilineatus, in the 
inner bark of black oak. 
