where the latter species is either rare or absent, this species is 
the primary vector of Dutch elm disease. 
The genus Hylastes Erichson is represented by 21 species in 
North America, several of which occur commonly in eastern 
United States (76). They usually breed in the bases or roots of 
dying pines and spruces or in stumps or the bottom sides of logs 
in contact with the ground. The adults occasionally kill pine 
transplants or young plantation trees by chewing the bases of the 
stems; otherwise, members of the genus are of minor economic 
importance. 
Hylastes porculus Erichson occurs from Maine to the Carolinas 
and west to the Lake States. It breeds in stumps and the roots of 
stumps and in dying pines. The adult is dark reddish-brown to 
black and from 4 to 5.3 mm. long. Adults are strongly attracted 
to freshly cut lumber or to current building operations. In the 
Southeast, they fly from April to November. 
Hylastes salebrosus Eichh. occurs commonly in the South At- 
lantic States. It has been recorded breeding in loblolly, longleaf, 
and shortleaf pines and spruces. It is also strongly attracted to 
freshly sawn lumber. The adult is dark reddish-brown and about 
4.5 mm. long. 
Hylastes tenwis Kichh. occurs over most of eastern United 
States from New York to Florida and Texas. Its hosts are listed 
as shortleaf, longleaf, and loblolly pines; spruce; and fir. The 
adult is dark reddish-brown to black and from 2 to 3.5 mm. long. 
Hylastes exilis Chapuis occurs in the Southern States from the 
District of Columbia to Florida and Texas. The adult is dark 
reddish-brown and about 2.9 mm. long. Its hosts are not known, 
but it has been collected while flying to downed pines. 
The genus Hylurgops LeC. is represented in eastern forests by 
only one species, H. pinifex (Fitch). It is widely distributed in 
eastern United States and Canada and breeds in logs, stumps, and 
basal portions of dead and dying pines, spruces, and larch. The 
adult is reddish-brown to nearly black and from 4.5 to 5 mm. long. 
The undersurface is black and the declivity is covered with small, 
ash-gray scales and a few long, erect hairs. 
The genus Hylocurus Eichh. contains a number of species that 
rear their brood in the wood of their hosts. In attacking the host, 
the adults bore directly into the sapwood or pith. Here they con- 
struct slightly enlarged nuptial chambers. From each chamber, 
one or several egg galleries are then extended obliquely through 
the wood or in several directions through the pith. The majority 
of species are of minor importance since they normally breed in 
recently cut, dying, or dead limbs of their hosts. Adults are quite 
small, 3 mm. or less in length. The head is concealed from above 
by the pronotum, which is strongly roughened in front; the first 
joint of the antennae is club-shaped; and the elytra are elongated 
and pointed at the apex. 
Hylocurus rudis (LeC.) breeds in the twigs and branches of 
hickory, walnut, maple, and hackberry throughout much of eas- 
tern United States. The adult is dark brown to black and 2.2 to 
3.0 mm. long. H. spadix Blackman, H. biorbis (Blackman), 4H. 
bicornus (Blackman), and H. harnedi (Blackman) breed in 
hickory. 
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