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Douglas fir. The eggs are deposited during the last week in August 

 and hatch in 5 days, the larvae working in all directions and girdling 

 the small limbs. Both sexes work at excavating the egg-chamber, 

 each pair j^robably making more than one of these. Dryocoetes 

 psexdoisugae, Swaine, is only kno^N^i to attack Douglas fir, its distri- 

 bution being along the Pacific coast from British Columbia to Northern 

 California. The young adults hibernate in the bark. The galleries 

 of this beetle are small and irregular. Adults, larvae and pupae 

 were all found in August. The development of a brood is complete 

 in 6 months. Ips concinnus, Mann., shows a preference for trees 

 with thin bark. It does not often attack Douglas fir, but is very 

 injurious to lodge-pole pine {Pinus contorta latifolia), and frequently 

 attacks injured, dying or recently felled Monterey pine {Pinus radiata) 

 and Sitka spruce {Picea sitchensis). Pityophthorus nitidulns, Mann., 

 does considerable damage in the spruce regions of Colorado. A small 

 central gallery is constructed under the bark, from which radiate 

 three or four galleries. There are 3 or 4 females and one male in each 

 chamber, each female depositing her eggs in a separate niche. The 

 larvae construct radiating galleries in all directions and pupate in a 

 cell almost wholly in the bark. When mature they eat their way 

 directly to the surface. 



Dendroct^nus pseudotsugae, Hopk. (Douglas fir bark-beetle) attacks 

 Douglas fir, big cone spruce {Pseudotsuga macrocarpa) and western 

 larch (Larix occidentaUs), but is evidently not strongly attracted to 

 the latter species in Oregon. This species is found from British 

 Columbia to Mexico, from the Pacific coast to the eastern slope of the 

 Rocky Mountains and from sea-level to 8,000 feet. Hibernation 

 occurs chiefly in the young adult stage, though some larvae are to be 

 found practically all the year round. In early March or April the 

 beetles extend their winter burrows or begin new ones, ovipositing 

 as the gallery progresses. Incubation requires 8 to 10 days in the 

 laboratory and probably about 16 days in the field. The young 

 larvae eat their way out through the cambium and pupate after a 

 period varying from 9 to 14 weeks. Broken logs, stumps and refuse 

 are preferred for breeding. The adults enter crevices or holes in the 

 bark and proceed to mine their way to the cambium. Here egg 

 galleries are excavated and breeding continues. The larval mines 

 are frequently longer than the main gallery and may cross and recross 

 many times. When mature, the beetle burrows straight to the surface 

 of the bark and so emerges. When badly attacked the foliage turns 

 colour, or only part of the tree may fail, showing that the cambium 

 has not been entirely girdled. D. pseudotsugae does not directly 

 damage the timber, but causes a loosening of the bark and hastens 

 the death of weakly trees. It is suggested that infested trees attacked 

 during spring or summer should be barked or burned before the middle 

 of August. The burning of any slashing that is infested before the 

 beetles become active (1st April) will helj) to keep the joest in check. 

 Two undetermined Ichneumonids have been reared from cocoons 

 found in the mines of D. pseudotsugae. One of these is undoubtedly 

 useful in keeping dowTi the beetles, 10 or 15 per cent, of the f)upal 

 cells being occupied by its cocoons. Seius safroi, Ewing (mss.), a 

 small mite fomid in numbers in the mines and ]3upal cells, Bdella 

 magna, Ewing (mss.), and the nymphs and adults of a Gamasid mite 



