INSECT ENEMIES OF EASTERN FORESTS 229 
which is composed of five ventral segments. The tarsi have five distinct 
joints. 
The adults of the families Bostrichidae and Lyctidae, the powder- 
post beetles, are distinguished from the Ptinidae chiefly by their 
larger size, elongate subeylindrical form, and the short first joint 
of the tarsi which is more or less immovably attached to the second. 
The larvae of these four families are very similar. They are white 
or yellow, soft-bodied, hairy forms, with prominent globular head and 
are curved like the white grubs or larvae of the snout beetles. They 
have well-developed, five- jointed legs. The ventral mouth parts are 
fleshy, and the submentum is continuous with the prothoracic skin 
(no gula); the maxillary mala is free and usually divided into a 
lacinia and often a spurlike galea. No hypopharyngeal bracon is 
present. They are further distinguished from closely related forms, 
as certain chrysomelids, by their wood-bori ing habits. 
The members of these four families are all wood borers, usually 
working in dry, well-seasoned material, and do considerable damage, 
especially in finished products, such as rough stock for implement 
handles or gun stocks, joists, beams and flooring of buildings, and 
stored high-« -orade lumber. The actual loss of the material is often 
only a small part of the damage. The value of the finished product, 
the replacement of damaged wood, or the inconvenience resulting 
from attack is frequently of much greater consequence. 
Many species continue to work for years in the same material, grad- 
ually consuming all the sapwood until nothing remains but a hollow 
shell or a core of heartwood. Some species are definitely associated 
with fungi, which produce a slow decay favorable to their existence, 
but whether or not this relationship is necessary for most forms is 
yet to be determined. 
A few forms such as Scobicia, which prefers freshly cut material, 
and Xylobiops which infests most heavily wood cut from 3 to 6 months, 
are injurious to stock used for rustic furniture, malls, ete. Xylobiops 
adults have also been found attacking dying persimmon trees that 
had recently become weakened as the result of a wilt infection. Some 
bostrichid adults have the curious habit of boring through solid ob- 
jects apparently out of pure curiosity to see what is on the other side. 
Twigs of trees, dry boards, and loaves of stale bread on the camp 
table, are attacked and tunneled. One western species, the lead-cable 
borer (Scobicia declivis (Lec.)), has won a notorious reputation be- 
cause of its bad habit of drilling into lead-sheathed telephone cables 
at the point of support, which. frequently results in short circuits 
(Burke, Hartman, and Snyder, 76). Recently, one of its eastern 
relatives, the apple twig borer (Amphicerus hamatus (F.)), has been 
found occasionally to have the same habit. 
In many species of these families the parent beetles cut egg tunnels 
much like those of the scolytids, boring directly in thr ough the sur- 
face for a short distance, the gallery “then turning at right angles 
and continuing under the sur face of wood in limbs, completely ¢ o1r- 
dling the material. The larval mines are tightly packed with fra ass. 
Many species are cosmopolitan, having been widely distributed in 
the products of commerce. The control of these beetles has been 
discussed on pages 39-42. 
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