COURTESY OF ILL. NAT. HIST. SURV. 
FIGURE 61.—Adult of the elm 
borer, Eutetrapha (= Saperda) 
tridentata. 
weakened trees. The larvae bore beneath the bark, filling their 
mines with fibrous frass, and completely destroying the phloem 
and cambium (587). When they reach maturity they bore into 
the wood and construct cells in which to pupate. There is usually 
one generation per year; however, in rapidly dried wood 3 years 
may be needed to complete the life cycle. 
Park and shade tree elms, especially the older ones and those 
in a weakened condition, are severely injured by this species. Af- 
fected trees tend to die very slowly, a branch at a time. The re- 
moval of infested branches is sometimes helpful in control. 
Smodicum cucujiforme (Say), the flat powder-post beetle, oc- 
curs throughout eastern United States. The larvae excavate ex- 
tensive meandering galleries in dry heartwood of oak and hickory. 
Stored lumber is frequently infested, the larvae continuing to 
feed in it until the wood is thoroughly riddled. The adult is small, 
elongate, very depressed, dull yellowish, shiny, and about 7 to 
10 mm. long. Adults appear in July and August. Eggs are laid 
in crevices of exposed wood. The larvae excavate tunnels in the 
wood about 3 mm. in diameter, tightly packing them with frass. — 
Pupation occurs in an enlarged portion of the mine near the 
surface of the wood. There is normally one generation per year. 
In dry wood, several years may be required to complete the life 
cycle. 
The genus, Oberea Mulsant, is represented in the Eastern 
States by a number of slender, cylindrical beetles, the larvae of 
which bore in the twigs, branches, or stems of various forest, 
shade, and ornamental trees. These beetles are distinguished by 
the presence of a broad tooth on each tarsal claw. 
The dogwood twig borer, Oberea tripunctata (Swed.) breeds in 
dogwood, elm, sourwood, laurel, azalea, Viburnum, and various 
fruit trees in eastern United States. The adult is yellowish and 
about 14 mm. long. The head is reddish or dark brown and there 
is a black spot on the scutellum. Adults appear in early spring 
and, after girdling the tip, the female deposits her eggs in living 
twigs of the host. The larva bores down the center of the twig, 
making a long series of holes for the expulsion of frass and cut- 
ting off portions of the twig as it bores on into the green wood. 
The winter is spent in the larval stage in the twig. Pupation oc- 
curs in the spring between two wads of fibrous frass. The portion 
189 
