324 MISC. PUBLICATION 657, U. S. DEPT. OF AGRICULTURE 
in infected elm, the beetles carry the disease to uninfected, cut, or 
broken elm, which thus acts as an additional reservoir of the fungus. 
Knull (268) and Collins (99) have described the scouting and control 
work in connection with the Dutch elm disease campaign. 
These elm bark beetles may be controlled by spraying with heavy 
dosagesof DDT. (See pp. 53-54.) 
ROOT AND BARK BEETLES OF THE GENERA HYLASTES AND HYLURGOPS 
In the genus Hylastes the antennal funicle is seven-jointed, the club 
oval, not compressed, distinctly segmented, with the first segment 
nearly as long as the others combined. In color the species range 
from brown to black, and in form from moderately slender to slender. 
The head has a short stout beak, which is better developed than in most 
other scolytids. 
The several eastern species of this genus breed principally in the 
bark of decadent trees and the stumps of felled trees, and are usually 
to be found in the inner bark at the bases of trees, near or below the 
surface of the soil. They choose bark which is quite moist or even 
wet, with an abundance of fermenting sap. Occasionally the adults 
will injure or even kill pine transplants or young plantation trees by 
chewing the bases of the stems. Usually, however, they are of little 
economic importance and may be ignored. In cases where they are 
damaging young trees, their breeding places should be discovered and 
treated. 
The more common eastern species are described as follows: Hylastes 
porculus Er. is black, moderately slender, more than 5 mm. long, and 
occurs from Maine to Michigan and southward to Virginia. AH. 
salebrosus Eichh. is slightly shorter and stouter than H. porculus, 
dark brown or black, and is more common in the South Atlantic States. 
H. scaber Sw. is closely related to H. porculus and is reported from 
Virginia, the District of Columbia, and Tennessee. H. tenwés Eichh. 
and Hf. exilis Chap. are two small, slender, brown species about 3 
mm. long, found from Virginia to Arkansas and southward to Florida. 
Several undescribed species are also known. 
The genus Hylurgops is closely related to Hylastes, but the eastern 
species, Hylurgops pinifea, is considerably stouter, and the elytral 
- declivity is covered with small ashy-gray scales and a few long erect 
hairs. ‘The habits are similar to those of [Tylastes, the base of the tree 
trunk being the preferred point of attack. H. pinifex is a secondary 
enemy of pines, spruce, and larch, and no control is necessary. It is 
widely distributed and common in eastern Canada and the northeast- 
ern part of the United States. 
Wood-Eating Bark Beetles 
Two closely allied genera of wood-eating beetles, Hylocurus Eichh. 
and Micracis Lec., contain a number of species that rear their brood 
not in the inner bark but in the wood or pith of their hosts. These 
two genera are similar in several respects. In both, the head is 
conces aled from above by the pronotum, which is strongly roughened 
in front ; the antennal club is compressed ; the tibiae of the foreleas have 
the sides nearly parallel, with the outer edge not serrate; and the 
elytra are elongated posteriorly to form an acuminate apex. In 
