9 
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 barkbeetle (Hylesinus n. sp.), 
the larger fir-tree barkbeetle (Hylesinus granulatus Lec.), and prob- 
ably other species. 
Two specimens of the parasite Syrphoctonus maculifrons 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 sear. Only 
one specimen was found. It resembled the maggots of the hemlock 
and jowland 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-worm (Parharmonia picew 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 
(Dendroctonus 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 
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