The genus Lyctus Fab. is represented in the United States by 
10 species, all of which feed in the sapwood portions of hard- 
woods. The wood of ring-porous species is more susceptible to 
attack than that of diffuse-porous species. Oak, hickory, and ash 
are highly susceptible. Other species often attacked include wal- 
nut, butternut, pecan, elm, sycamore, black locust, poplar, sweet 
gum, wild cherry, and osage orange. The extent of infestation 
and subsequent damage is proportional to the starch content of 
the wood. Since heartwood is practically free of starch it is 
immune. Wood infested for the first time may show very little 
external evidence of attack, even though the interior is seriously 
damaged; whereas the surface of older infested wood is per- 
forated with small, round pin holes (fig 37.). Any slight jarring 
of the wood causes a fine flour-like powder to sift through these 
holes. The presence of small piles of this powder beneath infested 
timbers is evidence of infestation. 
F-519936, F-519929 
FIGURE 37.—Lyctus powder- 
post beetle damage: A, 
frass packed tunnels in ply- 
wood; B, adult exit holes in 
arm of the frame of an up- 
holstered piece of furniture. 
The southern lyctus beetle, Lyctus planicollis LeC., is one of the 
most common of the destructive powder-post beetles in this coun- 
try. It is widely distributed, but is most injurious in the Southern 
States. Adults are usually black or almost black, have a wider- 
than-long prothorax with distinctly separated punctations on the 
disk, and are from 4 to 6 mm. long (fig. 38). The elytra are 
almost three times as long as wide, bear straight lines of fine 
long hairs, and are marked with double rows of elongate punc- 
tures. Seasoned or partially seasoned wood of oak, ash, and 
hickory are especially subject to attack. Freshly cut wood is not 
attacked. 
Eggs are laid in the open ends of pores of longitudinal vessels 
in the wood, at depths of 4 to 7.5 mm. Hatching occurs within a 
week or two. The larvae burrow through the wood; their tunnels 
run parallel with. the grain and are filled with fine powdery dust. 
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