INSECT ENEMIES OF WESTERN FORESTS 193 



thorax somewhat darker than the wing covers. The sides of the 

 prothorax are armed with a few large or many small teeth or 

 spines. They are often found flying around lights early in the sum- 

 mer. Eggs usually are laid in crevices of the bark of dead trees 

 or stumps, and the larvae excavate large channels and pack them 

 with coarsely chewed wood fiber, in the sapwood and then into the 

 heartwood. When full grown the large, thick-bodied larvae are 

 often 2y 2 inches in length, creamy white, with reddish heads 

 bearing plates armed with four spines just above the mandibles. 

 The species is found throughout the Western States, commonly 

 attacking Douglas-fir and pines. 



The California prionus (Prionus calif ornicus Mots.) is similar 

 to the ponderous borer. The larvae feed in the roots of oak, alder, 

 poplar, and other hardwoods, and also in such coniferous roots as 

 pine, redwood, Douglas-fir, and fir. Sometimes they bore into the 

 roots of living trees. The adults usually have three prominent 

 spines on the lateral margins of the prothorax. It is distributed 

 in the Pacific coast region from Alaska through California and 

 eastward into the Rocky Mountain region and the Southwest. 



Tragosoma harrisi Lee. is a more slender reddish-brown beetle 

 about 1% inches long, which breeds in the sapwood of dead lodge- 

 pole, ponderosa, and other pines in the colder parts of the West. 



The larvae of the genus Monochamus, known as sawyers, are 

 responsible for extensive damage to dying and recently killed and 

 felled trees throughout the United States. The females chew ir- 

 regular 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 outward to the bark several inches from the point of en- 

 trance, 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 sawdust. As the larva nears 

 maturity the borings are no longer ejected, and the galleries are 

 packed solid, with the exception of a small cell at the end of the 

 gallery in which pupation occurs. The mature adult emerges by 

 gnawing a round hole through the thin 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 north- 

 ern 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. 

 90) is from y 2 to 1 inch long, 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 1% inches in length, are destructive to fire- 



