the posterior margin of the abdomen is lacking in the male. This species differs 
from other eastern Scolytus by its oblique second abdominal sternite. Dying and 
weakened limbs and freshly cut wood are preferred for breeding purposes. The 
gallery system is slightly larger but similar to that of the smaller European elm bark 
beetle. When fully grown, larvae bore cells into the sapwood where they overwinter 
and pupate in the spring. There is one generation per year (972). 
The hickory bark beetle, S. guadrispinosus Say, occurs from southern Quebec 
to Georgia, Alabama, and Mississippi and west to Minnesota, Kansas, Oklahoma, 
and Texas. Its range is probably coincident with the natural range of hickories. This 
species is a serious pest of hickories and has also been recorded feeding on 
butternut and pecan. The adult is stout, black, almost hairless, and 4 to 5 mm long. 
The venter of the male is deeply excavated. The third abdominal segment 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 where they construct rather short (ca. 3 cm), longitudinal egg galleries 
between the bark and wood (fig. 166). 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 niches at each side of the gallery. The larvae feed 
across the grain until nearly fully grown, then they abruptly turn and mine parallel 
to the grain. 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 spring. There is one generation per year in northern 
areas. In the South, there are normally two broods per year. 
Courtesy Duke Univ. Sch. For. 
Figure 166.—Galleries of the hickory bark beetle, 
Scolytus quadrispinosus, in phloem of hickory. Note 
short vertical egg galleries and fan-shaped larval 
galleries. 
355 
