30 BULLETIN 360, U. S. DEPARTMENT OF AGRICULTURE. 
of 1914, a large number of badly suppressed Douglas firs on the foot- 
hills bordering the Clark Fork (Missoula River) Valley have died 
from a combined attack of mistletoe and beetles. Most of these trees. 
which supported scarcely a single normal branch, had the bark of 
limbs and trunk almost entirely removed by woodpeckers in their 
search for the beetle before the leaves were entirely dead. The few 
uninfected Douglas firs of the same region have not been attacked by 
the beetles. 
The branches of large mistletoe brooms on yellow pine and Doug- 
las fir from which the parasite has entirely disappeared are very 
Fic. 27.—Seats of original mistletoe infection on two living branches (in center and at 
left) of mistletoe brooms on yellow pine infested with bark beetles. No other part of 
the broom or tree was attacked. Main stem of young living yellow pine (at right) 
attacked by bark beetles at the seat of an old mistletoe infection. 
frequently found infested with bark beetles (fig. 27), while the trunk 
and normal branches of the trees are entirely free from attack. 
INFLUENCE OF MISTLETOE INJURY ON THE SEED PRODUCTION 
OF THE HOST. 
Germination tests of seeds of yellow pine taken from mistletoe- 
infected trees show that the percentage of germination is consid- 
erably lower than is the case with seeds taken from normal trees 
(12, p. 7). Experiments conducted by the writer with seeds taken 
from cones produced on very old mistletoe brooms of Douglas fir, 
larch, and lodgepole pine showed a germination on an average of 
10 per cent below that of seed taken from uninfected branches of 
