variety of trees. Some of its more important eastern hosts are 
pecan, hickory, honey locust, walnut, sweetgum, yellow poplar, 
dogwood, persimmon, holly, hemlock, cypress, and shortleaf and 
loblolly pines. The adult is light brown to black and from 1.5 to 
2.2 mm. long. The female scutellum is conical; the elytral declivity 
steep and armed with rows of acute granules. There is also a 
tooth-like tubercle on each side of the suture. The slope of the 
declivity of the male begins so high on the elytra that the beetle 
is humpbacked in appearance. The gallery of the species consists 
of a single tunnel bored directly into the wood. Once inside it is 
widened into a chamber in which eggs are laid and in which the 
larvae live and feed. The life cycle is short and can be completed 
in 2 months. 
Xyleborus celsus Eichh., the largest member of the genus oc- 
curring in the United States, breeds in dead, dying, and recently 
felled trees and stumps of hickory in eastern United States west 
to Kansas. Adults are light reddish to reddish-brown and about 
2.3 to 4.45 mm. long. The declivity of the female is steep and 
abrupt, the sides and upper margin are armed with several acute 
granules, and there are four large teeth opposite the second inter- 
space. The galleries of the species extend directly into the wood 
to a depth of 12 to 18 mm., then branch one or several times. 
Hickories killed by the hickory bark beetle are especially subject 
to attack in the Southeast. 
Xyleborus ferrugineus (F.) occurs from New York and Michi- 
gan south to Florida and Texas. It breeds in dead, dying, or felled 
trees of a wide range of species including oak, hickory, ash, cy- 
press, walnut, pine, beech, and sweetgum. Adults are light reddish 
to reddish-brown and from 2 to 3 mm. long. The elytral declivity 
of the female is flat. The third interspace is armed with three 
acute granules; the fourth and fifth interspaces are armed with 
two to four granules each. Galleries resemble those formed by X. 
celsus except that they are smaller; they also may be longer and 
more winding and branch less frequently in the same plane. Side 
branches are formed which lead to other sets of galleries at 
different levels. 
Xyleborus affinis Eichh. occurs in eastern United States east of 
a line from Michigan to Texas and south of New York. It breeds 
in dying trees and in green logs and lumber of various hardwood 
trees such as oak, hickory, sweetgum, river birch, hackberry, 
mimosa, persimmon, cypress, and black locust. Adults are light 
reddish to reddish-brown and are from 1.8 to 2.8 mm. long. The 
elytral declivity of the female is dull, opaque, and broadly slop- 
ing, and the interspaces are armed with a few minute granules. 
Galleries consist of short, transverse entrance holes and elongate 
tunnels from which many transverse galleries often branch. This 
species is very destructive of sweetgum in the Gulf Coast States. 
Xyleborus xylographus (Say) occurs in eastern Canada and in 
the United States west to Kansas. It reportedly attacks the lower 
portions of dying trees and the stumps, roots, and slash of its 
hosts. Oak appears to be favored, but hickory, chestnut, walnut, 
and pine also are attacked. Favorite points of entry appear to be 
the edges of wounds, deep crevices, or burrows made by other 
insects. Adults are yellowish or reddish-brown to black and from 
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