SB 
818 lo. 61. 
578 
ENT ited States Department of Agriculture, 
BUREAU OF ENTOMOLOGY, 
L. O. HOWARD, Entomologist. 

BLACK CHECK IN WESTERN HEMLOCK. 
By H. E. BurKE, Special Iield Agent. 
ECONOMIC IMPORTANCE. 
Black check is the lumberman’s name for a common defect, consist- 
ing of a dark brown or blackish resinous scar, in the wood of the western 
hemlock. A few layers of the wood beneath this scar are slightly 
stained for a short distance around, and all 
of those above are thickened, curled, or in 
some way abnormal. When seen in a 
quarter-sawn board (radial section) the 
defect appears as a small, thin seam (fig. 1) 
from one-half to one inch long, with one 
side curly. In a bastard-sawn board (tan- 
aoe, = F 
SS 








gential section) it is an oval or circular 
spot (fig. 5, g) that varies in diameter from 
one-half to one inch. In both cases it lies 
with the grain of the wood. 
























Hemlock timber growing on lowlands 
is often seriously affected, while that on- 
higher land, especially above an altitude 
of 1,800 feet, appears to be free from the 
injury. In a large quantity of box stock 
cut from lowland timber, nearly every 
board examined by the writer contained 
numerous examples of the defect. 

































































































Timber badly affected with this defect 
is nearly worthless for finishing, turning, 
=)? Fig. 1.—Longitudinal section of 
staves, and woodenware, for which it would a board approximately quar- 
otherwise be excellent. The injury is very pM reee 
conspicuous in bastard-sawn lumber, un- 
fitting it for finishing or turning, while in that quarter-sawn (fig. 1) or 
cut across the grain it is apt to form an open seam which renders it 
worthless for staves and woodenware, where tightness is required, but 
it would appear that it is not materially detrimental to timber for con- 
struction and other purposes. 
Taking into consideration the common occurrence and injurious effect 
of the blemish in lumber for certain purposes, and the large amount of 
timber concerned, the total loss caused by the check must be considerable. 
