The work of the two species is very similar. The fir is a more rapidly 

 growing tree than the hemlock and the wounds under the bark, there- 

 fore, go deeper into the sapwood. These wounds, also, occur more 

 often in patches. The primary injury is made by several species of 

 barkbeetles, viz, the western hemlock bai-kbeetle {Hylesinus n. sp.), 

 the larger fir-tree barkbeetle {Hylesinus grarmlafiis Lee), and prob- 

 ably other species. 



Two specimens of the parasite SijrpJioctomis niacuUfrons Cr. were 

 bred from the resin masses. No other enemies were seen. 



Satsop was the only place where the trouble was noticed'. The amount 

 of damage done and the distribution of the insect causing it are not 

 known. 



THE ALPINE FIR BARK MAGGOT. 



On October 24, 1904, a bark maggot was found in a resinous wound 

 on the trunk of an alpine fir at Smith's Ferry, Boise County, Idaho. 

 The wound seemed to have been started from an old limb scar. Only 

 one specimen was found. . It resembled the maggots of the hemlock 

 and lowland fir, and is probably the larva of another species of Cheilosia. 

 The amount of damage it causes was not determined. 



THE SITKA SPRUCE BARK MAGGOT. 



A maggot closely' resembling the other species, except that it has a 

 short tail, is quite common in the wounds on the trunks of Sitka spruce. 

 It is usually found in the pitch around the edges of the large resinous 

 wounds caused by the spruce -pitch-worra( Parharmonia picece Dyar). 

 Several maggots live in the same wound, and the irritation produced 

 by their feeding keeps it open for so long a time that an ugly scar is 

 formed in the wood. Several generations may live in the same wound. 

 Pupation takes place in the drying resin of the wound. This is prob- 

 ably a species of Cheilosia. Hoquiam, Wash., was the only place where 

 the trouble was noticed. 



THE YELLOW PINE BARK MAGGOT. 



A dark, subcylindrical dipterous puparium was very common in pitch 

 exuding from axe and other wounds in the bark of young yellow pine 

 {Pinus ponderosa) trees at Moscow Mountain, Idaho, and barkbeetle 

 {Bendroctmms sp.) and sapsucker wounds in the bark of the young 

 trees of yellow pine, and the lodgepole pine {Pinus murrayana) at 

 Smith's Ferry, Idaho. No adults were reared. The species is probably 

 a syrphid, possibly a Cheilosia, though the puparium does not resemble 

 those of Cheilosia alaskensis and hoodianus. The amount of damage 

 done is unknown. 



CONCLUSIONS. 



(1) Western hemlock timber growing on low land is often affected by 

 a defect known as black check, which renders a large percentage of the 



