252 MISC. PUBLICATION 657, U. S. DEPT. OF AGRICULTURE 
Stenodontes (Mallodon) dasystomus (Say), the hardwood stump 
borer, is a very large, elongate, somewhat flattened, reddish-brown 
beetle from 30 to 45 mm. in length, having the sides of the prothorax 
armed with many small flat teeth. The head is large. The larva is 
large and cylindrical, with a smooth shining skin, having the head 
wider than long, retracted into the prothorax, and the front produced 
in a smooth transverse carina, or scarcely projecting. Two small 
groups of 5 to 12 chitinous points are found on the under side of the 
prothorax. The ampullae bear two transverse impressions. Legs are 
present. 
The larvae feed gregariously for 3 or 4 years in the heartwood of 
living trees, particularly in the bases, making large mines which are 
packed with coarse fibrous frass. They completely honeycomb the 
heartwood of willow, oak, boxelder, sycamore, and other hardwoods 
from Virginia south and west throughout the Southwestern States. 
The pupal cell is constructed deep in the wood, closed behind by a 
fibrous plug of frass. The adult gnaws out through the wood in mid- 
summer. Cross ties and similar material in contact with the ground 
are often badly damaged. The heartwood of shade trees often be- 
comes infested, and an entire tree may be hollowed out, frequently 
resulting in its breaking over during a storm. For the control of such 
borers see page 24. 
A related species of the hardwood stump borer, Archodontes 
(Mallodon) melanopus (1.), is injurious to trees in the Southern and 
Southwestern States. It is recorded as injurious to the roots of living 
oaks, causing the formation of large galls and often killing the trees 
or causing stunted growth. 
Four species of J/onochamus are of economic importance in the Kast : 
The southern pine sawyer (J/. titillator (F.)) in the Eastern and 
Southern States, the white-spotted sawyer (M/. scutellatus (Say) ) 
throughout the United States, except the southern part, the northeast- 
ern sawyer (IM. notatus (Drury)) in the Northern States, and the 
balsam-fir sawyer (J/. marmorator (Kby.)) im the Northern States. 
These are large, elongate, cylindrical beetles from 15 to 30 mm. in 
length, black to brownish-black, and more or less mottled with whitish 
or grayish pubescence. The thorax is cylindrical, having a spine at 
each side, and both the antennae and legs are very long. 
The larvae are elongate, somewhat flattened, or cylindrical when 
full grown, having the head longer than wide and very depressed, 
and the mandibles. obliquely pointed at the apex. The pronotum is 
posteriorly brownish and finely asperate, and the dorsal ampullae 
bear four rows of finely asperate tubercles. They are legless. Boring 
beneath the bark of recently killed or felled pine, spruce, and balsam- 
fir trees, the larvae fill the mines with fibrous frass (fig. 54, C’). 
peel after the pine pollen is shed, the adults appear and gnaw 
ral pits through the bark of trees felled or killed the preceding spring 
or winter and “insert from one to several eggs in each. The young 
larvae bore beneath the bark for 40 to 60 da ays, converting the inner 
bark and wood into coarse shredded frass. Much of the frass may 
be exuded. Later the larvae enter the wood to make a deep U- shaped 
cell through the sapwood and heartwood, the entrance being plugged 
with frass, while the opposite end is enlarged into a pupal cell. Pupa- 
tion occurs in the following spring or early summer, and the adult 
