206 MISC. PUBLICATION 273, U.S. DEPT. OF AGRICULTURE 



ance of bark beetles. This species is common in California and 

 Oregon. 



The softwood powder-post beetle (Hadrobregmus gibbicollis 

 (Lee.)) (53) probably is the most destructive of the native pow- 

 der-post beetles found in the Pacific Coast States. The adults are 

 elongate brown beetles about % inch in length, and the larvae are 

 small white, curled grubs with three pairs of legs and an enlarged 

 thorax. This species breeds in old, well-seasoned Douglas-fir tim- 

 bers such as bridges and basement supports. Dry, unrotted, wide- 

 grained sapwood is preferred. Attacks are most common in base- 

 ment timbers and in other shady locations where a certain amount 

 of moisture is present. Reinfestations continue year after year 

 until the wood is reduced to a powder, leaving only an outer shell. 

 On completing development the adults leave round holes nearly 

 y s inch in diameter on the surface of the wood. This beetle is not 

 restricted to Douglas-fir, but has been found in limbs of redwood, 

 bigleaf maple, and bitter cherry, and probably will attack other 

 well-seasoned woods of suitable texture. It can be controlled by 

 swabbing the wood with a 5 percent solution of pentachlorophenol 

 in a light fuel oil, or by applying orthodichlorobenzene or other 

 suitable wood penetrants. 



CARPENTER ANTS 



Large black ants belonging to the genus Camponotus are called 

 carpenter ants because of their habit of tunneling into the wood 

 of stumps, logs, dead standing trees, or the dead interior of living 

 trees, and even into the framework of houses. There they excavate 

 large cavities that they use for nests in which to rear their young. 

 The wood is not eaten by the ants, but cast out to make room for 

 the nests, causing little piles of wood fibers to collect below the 

 entrance holes. Their excavations in wood are frequently so exten- 

 sive as to seriously impair its structural value (fig. 99) . In the 

 Pacific Northwest carpenter ant damage greatly exceeds and to a 

 large extent supplants that done by termites, the termite damage 

 being much more prevalent farther south (55). These ants are 

 general feeders, including in their fare both animal food and 

 sweets, their preferred items of food appearing to be the cater- 

 pillars of certain lycaenid butterflies and the honey-dew excreted 

 by aphids. They have even been known to shelter the aphid eggs 

 in their nest during the winter and carry them out and place them 

 on plants to develop in the spring. 



These species differ from some of the other ant species in that 

 the queen carpenter ant works alone in founding a colony. An 

 interesting feature is that, from the time the queen builds her cell 

 and begins to lay eggs until a brood of workers mature, no food 

 is taken into the cell. This covers a period of about 10 days from 

 the laying of the egg to the larval stage and perhaps 30 days more 

 before the workers are mature and begin to carry in food. It is 

 generally supposed that the queen carries enough food within her 

 body to feed the growing workers, apparently by regurgitation. 



Carpenter ants are difficult to control, and at times all remedies 



