bark, grooving the surface of the wood, parallel with the grain 
(fig. 84 B). Eggs are deposited in niches along the sides of the 
gallery. The maternal gallery is typically unbranched and runs 
parallel to the grain. This distinguishes it from the maternal 
gallery of the native elm bark beetle which is Y-shaped or bira- 
mous. The larvae feed in the inner bark and the surface of the 
wood, angling away from the gallery. When they become full 
grown, they form cells in which to pupate in the bark. During the 
spring and summer, the life cycle may be completed in 35 or 40 
days. In the United States there usually are two generations per 
year. Farther north in Canada, there are one and a partial second 
generations per year. 
Because of its role in the transmission of Dutch elm disease, 
the smaller European elm bark beetle has been the subject of con- 
siderable research, and huge expenditures have been made in 
efforts to eradicate or control it. Efforts to eradicate it proved 
futile, but much progress has been made in research on its con- 
trol. So far, the most effective known method of reducing losses 
is the destruction of beetle breeding places (762). 
Scolytus mali (Bechst.) (=sulcatus Say) occurs in Connecti- 
cut, New York and New Jersey, and probably in surrounding 
states. It breeds in apple, cherry, and elm. The adult is from 3.4 
to 4.4 mm. long, and is about one-half as wide as long. The elytra 
have the punctures arranged in regular strial and interstrial 
rows of nearly equal size. The abdomen is weakly concave on the 
ventral side. The fifth sternite is longer than the third and fourth 
combined and the posterior margin of the abdomen is lacking in 
the male. The adult occasionally feeds in the twig crotches of elm 
and is capable of transmitting the Dutch elm disease fungus. 
Dying and weakened limbs and freshly cut wood are preferred for 
breeding purposes. Winter is spent in the larval stage in the 
bark, and there is one generation per year. 
The hickory bark beetle, Scolytus quadrispinosus Say, a serious 
pest of hickories, occurs from Quebec to Georgia, Alabama, and 
Mississippi and west to Minnesota, Kansas, Oklahoma, and Texas. 
It has also been recorded feeding on butternut and pecan. The — 
adult is short, stout, black, almost hairless, and 4 to 5 mm. long. 
There is a short curved spine or hook on the front tibia. The 
venter of the male is deeply excavated. The third abdominal seg- 
ment is armed with three spines, the fourth, with one large 
median spine. The venter of the female is without spines. 
Adults appear in early summer and feed for a short time at the 
bases of leaf petioles and on the twigs of hickory before flying to 
the trunks and branches of living trees, and boring into the bark. 
Here they construct rather short, longitudinal egg galleries be- 
tween the bark and wood (fig. 85). In thick-barked trees, the 
gallery may scarcely touch the wood; in thin-barked limbs it may 
occur almost entirely in the wood. Eggs are deposited in pockets 
at each side of the gallery. The larvae feed in the phloem until 
nearly full grown, and gradually angle away from the gallery. 
Before reaching maturity they leave the phloem and bore into 
the bark where they construct cells in which to pupate. The 
winter is spent in the larval stage and pupation occurs in the 
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