local “‘spot” populations of southern pine beetles (/026), and using pheromone 
lures for mass trapping European elm bark beetles has contributed to control of 
Dutch elm disease in urban areas (7/6). Parasites and predators (especially wood- 
peckers) may keep endemic-level bark beetle populations from increasing, but 
probably do not cause the collapse of outbreaks. Foresters can assist in biological 
control of bark beetles by leaving a few dead and defective trees for nesting of 
woodpeckers rather than felling all cull material during thinning and logging 
operations. 
A trap-log technique can be used beneficially against bark beetles that preferen- 
tially attack cut material. Trees are felled shortly before beetles are expected to fly. 
Infestation may occur naturally or be assured by baiting the trees with synthetic 
aggregation pheromone. Before beetle broods mature, logs are debarked, milled, 
etc. Although this method has been applied effectively against [ps typographus (L.) 
in Europe for three centuries (/074), it has not been widely applied in North 
America. A modified trap technique in which trees are killed with cacodylic acid 
and baited with pheromone is more efficient because herbicide-induced drying of 
the bark inhibits brood development and renders follow-up action unnecessary 
(943, 1233). The most satisfactory means of reducing losses to bark beetles is to 
prevent the occurrence of outbreaks by maintaining sanitation of logging debris, 
lightning-struck or windthrown trees, etc., and by promoting stand vigor by 
thinning and other cultural practices (85). Loss in quality of softwood logs due to 
bark beetle-carried stain fungi can be avoided by prompt milling, ponding, or 
sprinkling of logs. 
Subfamily Hylesininae 
The genus Hy/urgops is represented in eastern forests by only one species, H. 
pinifex (Fitch). This species is widely distributed in the Eastern United States and | 
Canada where it 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 Hylastes is represented by 15 species in North America, several of 
which occur commonly in the Eastern United States (/2/). 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 roots of 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 ongoing construction. In the Southeast, they fly during the period 
April to November. 
Hylastes salebrosus Eichhoff occurs commonly in the south Atlantic States. It 
has been recorded breeding in loblolly, longleaf, and shortleaf pines, and in 
spruces. It is also strongly attracted to freshly sawn lumber. The adult is dark 
reddish-brown and about 4.5 mm long. 
Hylastes tenuis Eichhoff occurs over most of the United States. Its hosts include 
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 where it infests various species of pine. The adult 1s 
dark reddish-brown and about 2.9 mm long. 
340 
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