Wind is undoubtedly the major agent of spore dissemination, 
but some spread is also probably effected by insects such as the 
bostrichid, Xylobiops basilaris (Say). The adults of this species, 
some of which attack healthy trees, become contaminated when 
they emerge through spore masses on dying trees. Feeding in- 
juries on the terminals and twigs by adults of the twig girdler, 
also serve as entry courts for wind-borne spores (172). 
Blue stains.—In 1928, it was suggested that blue-staining fungi 
were probably introduced into pines by bark beetles and that they 
played important roles in the killing of trees (166). This was 
later confirmed (564). Blue-staining occurs mostly in felled 
timber but also may be found in beetle-infested trees weakened by 
fire, drought, and other adverse factors. 
Ceratocystis minor (Hedgec.) Hunt one of the most important of 
the blue-staining fungi in eastern United States, is introduced into 
pine trees by the southern pine beetle. It does not cause decay but 
stains the wood which may greatly reduce its market value. In 
living trees, it also interferes with transpiration, and the trees die 
from the top downward. 
Ceratocystis ips (Rumbold) C. Moreau is introduced into south- 
ern pines by the engraver beetles, /ps calligraphus and I. grandi- 
collis, and it produces a stain that spreads inward from the beetle 
galleries toward the heartwood (fig. 208). This fungus has also 
been found in living and felled red pines in the Lake States at- 
tacked by J. pini and I. grandicollis (450). 
: 5 
ye 
ca 
3 
COURTESY OF DUKE UNIV. SCH. OF FOREST. 
FIGURE 208.—Cross-section of bole 
of shortleaf pine killed by Ips 
calligraphus, showing develop- 
ment of blue-stain fungus, Cera- 
tostomella ips, in sapwood. 
F-519913 
FIGURE 207.—Oak tree killed by 
the oak wilt fungus, Ceratocystis 
fagacearum. 
