20 BULLETIN 1128, U. S. DEPARTMENT OF AGRICULTURE. 
SAPSUCKER WOUNDS. 
Sapsuckers are a group of woodpeckers which extract the sap 
from the inner bark and sapwood of living trees and eat the cambium. 
The final result after the wound has healed or callused over is the 
so-called bird pecks (15, 35). This injury is often accompanied by 
extensive staining, particularly in the hardwoods. On the ends of 
logs or boards the healed wounds appear as stained areas of varying 
size, each containing a more or less open, short, radial check in con- 
nection with distorted grain. The general appearance is a T-shaped 
or triangular mark or check surrounded by a stain varying from 
brown to almost black. More than one usually occurs in the same 
annual ring. On the edge-grain or slash-grain faces of sawed lumber 
these injuries usually appear as small knots or distortions in the 
erain, surrounded by more or less stain which is usually localized, 
but the stain may be accompanied by a bleaching which extends for 
some distance. ‘The stain is always adjacent to the distorted grain, 
and the more distorted the grain the greater 
the extent of the stain. | 
The stain appears to be the most injurious 
of the two, but in reality the distorted grain 
is the only cause of weakening in the wood. 
The strength of the wood is not much affected, 
so that wood with bird pecks in most cases 
can be safely utilized: Figure 6 shows a sec- 
tion from a white-ash longeron with a minor 
injury of this kind which does not impair the 
usefulness of the member. Pieces are some- 
Fic. 6.—Section from a times unsuitable for handles, owing to the 
ine a “sapekcker’ fury tendency of the grain to roughen up at these 
or bird’ peck “im white” places when’ planed.-:1i fhe pecksoaregnu. 
merous 1n one annual ring it is best not to 
use the piece, for although it has not been determined by comparative 
tests it is quite probable that such material is reduced in strength. 
Checks or wind-shakes are very prone to occur along an annual ring 
containing numerous sapsucker wounds or even at individual in- 
juries. These often prove to be serious in thin veneer, since pieces of 
the distorted grain are likely to fall out. Sapsuckers are responsible 
for much of the curly grain and bird’s-eye found in tulip poplar. 
Both stain and bird’s-eye in this species are shown in Figure 7. 
Practically all tree species, both softwoods and hardwoods, are 
subject to this type of injury, but hard maple, soft maple (Acer sac- 
charinum Linn.), tulip poplar, and hickory in particular stain badly. 
The bird pecks are common in white ash, but the accompanying 
stain is generally closely localized. 
-PITH-RAY FLECKS. 
Pith-ray flecks, which are also termed medullary spots and pith 
flecks, are caused by the larve or grubs of certain insects living in 
the cambium of living trees during the growing season (10, 17, 20, 
21, 44, 67). These insects comprise several species of the genus 
Agromyza belonging to the order Diptera. On the end section of 
logs or lumber the flecks appear as small brown crescent or half-moon 
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