152 MISC. PUBLICATION 273, U. S. DEPT. OF AGRICULTURE 
SAWYERS 
The larvae of the genus Monochamus, known as sawyers, are re- 
sponsible for extensive damage to dying and recently killed and 
felled trees throughout the United States. The females chew irreg- 
ular pits in the bark, and in these from one to six eggs are placed. 
The larvae, which are elongated, footless, whitish grubs, feed from 
4 to 8 weeks between the bark and wood, loosening the bark and 
filling the space between bark and wood with long fibrous borings. 
Later the larvae enter the wood, forming small oval holes, that 
become nearly round as the larvae mature. These tunnels extend 
through the sapwood, often into the heartwood, and then turn out- 
ward to the bark several inches from the point of entrance, thus 
making U-shaped burrows in the wood. During the early stages of 
larval development 
the borings are 
dropped from the 
galleries and form 
small piles of saw- 
dust. As the larva 
nears maturity the 
borings are no longer 
ejected, and the gal- 
leries are packed 
solid, with the ex- 
ception of a small 
cell at the end of the 
gallery in which pu- 
pation occurs. The 
mature adult emerges 
by gnawing a round 
FIGURE 75.—Spotted pine sawyers (Monochamus maculosus) pole aie tas ulm 
2 XS. ’ layer of wood and 
bark which separates 
the pupal cell from the surface. Though the life cycle of these insects 
is usually completed in 1 year, in the northern portion of the range 
two seasons are often required. The adult beetles, during flight and 
egg laying, feed upon the needles of conifers, and some species gnaw 
the bark from young twigs, many of which are killed. 
The spotted pine sawyer (Monochamus maculosus Hald.) (fig. 75) 
is from one-half to 1 inch in length, drab brown, with grayish, 
irregular-shaped markings. The prothorax is of the same width as 
the head and has a prominent toothlike projection on each side. The 
larvae, which range from 1 to 134 inches in length, are destructive 
to fire-scorched, dying, or recently felled pines and Douglas fir 
throughout the Western States. 
The Oregon fir sawyer (Monochamus oregonensis Lec.) is a stout, 
black beetle, approximately one-half to 114 inches in length, with 
gray markings, antennae about twice as long as the boay, and a 
toothlike projection on each side of the prothorax. The larvae range 
from 1 to 134 inches in length and are destructive to fire-scorched, 
injured, dying, or recently felled Douglas fir, balsam firs, and other 
coniferous trees of the Western States. This is the western variety 
of the eastern black pine sawyer (JZ, scutellatus Say). 
