INSECT ENEMIES OF EASTERN FORESTS 261 
of the trees, cutting off the sap movement, which results in the death of 
the trees. Small trees are badly damaged by the deeply gnawed egg 
scars. Also, the stems are greatly weakened so that the trees break 
off in the wind. For description and habits of this insect, see Milliken 
(304). 
Control measures are given on pages 24-26 of this publication. 
The root-boring prionids of the genus Prionus Geoff., are heavy, 
robust, black or brownish-black, shining beetles from 25 to 45 mm. 
long, having the sides of the prothorax margined and bearing three 
teeth. The antennae are imbricated in the males. The larvae are 
elongate, rapidly tapering posteriorly, with a tough shining skin. The 
head is wider than long, retracted into the prothorax, and the front is 
produced in a straight smooth carina divided in the middle. On each 
of the first six abdominal segments is a small radially striate disk just 
below the spiracles. Legs are present. Several weeks or a month after 
the chestnut is in full bloom the adults fly, soon laying their eggs and 
then dying. All the larvae studied require 4 or occasionally 5 years 
to mature. The pupal stage extends from 4 to 8 weeks. 
These borers (Prionus pocularis Dalm. excepted) feed in the root 
bark on living trees or shrubs during the early larval stages but soon 
enter the wood, completely hollowing large roots and often severing 
them. They crawl through the ground from root to root, feeding also 
on the outer surfaces of the smaller roots and causing many injuries 
and wounds. Often the hollowed roots are here and there filled with a 
mixture of coarse pelletlike excrement and coarse fibers and earth. In 
the early spring months the matured larvae come to within 3 to 5 
inches of the surface, where they make a large oval cell of compact 
earth in which the pupal stage is passed. 
It is difficult to estimate the extent of the injury resulting from feed- 
ing by these borers. They are very often associated with the Armz/- 
laria root disease and seem to prefer mature trees in open stands. 
These borers are abundant in pastures and hill slopes on gravelly well- 
drained soil, in places where the trees grow under unfavorable condi- 
tions, and in much-used parks where the ground is packed and no 
humus is present. On certain park areas where these insects were 
abundant many roots were badly eaten and many were completely 
severed. For many years these trees were under-observation by Dr. 
Hopkins, who says that they gradually died hmb by limb. The foliage 
appeared irregularly and was thinner and lighter in color on many 
branches than healthy foilage. Under other conditions where the soil 
was poor, no humus was present, and certain root diseases and second- 
ary insects were associated with these borers, malformation and death 
of the trees was very rapid. It is believed that the presence of these 
borers in numbers usually indicates other unfavorable conditions under 
which the trees are struggling. 
Shrubbery and small trees are attacked by certain species of these 
borers, and the roots may be occasionally cut off near the surface of 
the ground, resulting in rapid death of the plant. Four species may 
be mentioned by name. 
The tile-horned prionus (Prionus imbricornis (.)) occurs most 
commonly through the Southeastern States and is probably the most 
injurious of the species here considered. It is chiefly found on oak 
and chestnut but will attack other hardwood trees. The California 
