THE ZIMMEKMAN PINE MOTH. 7 
mature trees (see Pinipestis camoiicola, p. 6) and this is evidently 
the reason why its activities bear no permanent fruit. Considering 
also that the birds in hunting for the larva? strip the trees of as 
much bark and cambium as the moth larva? destroy in one generation, 
and that this operation is repeated each season, it is doubtful whether 
the woodpecker cure is not as bad as or even worse than the moth evil, 
when one considers that the brood trees are allowed to replenish the 
ranks of the insect year after year. (PL IV.) 
The cocoon of a pimplinid of a new genus and new species 1 is fre- 
quently found in the tunnels of the pine moth in Montana and Idaho. 
In some localities this parasite kills as many as 80 per cent of the 
larva? of the moth in second-growth trees. As the parasite cocoons 
are not molested by woodpeckers, a full quota of this fly emerges 
during the first warm days of each spring. While this parasite 
greatly aids in checking the increase of the moth from larva? which 
infest second growth, it fails, as does the woodpecker, to pursue the 
caterpillars in the above-mentioned brood trees. Hence it is as 
much of a signal failure as is the bird. 
Another, somewhat larger parasite (Ichneumon n. sp. 1 ) is fre- 
quently found during winter in the chrysalis of the moth. The moth 
does not pass the winter in the pupal stage, and chrysalids found at 
that time always contain the parasitic fly, which, like the pimplinid, 
emerges during early spring. It is apparently less numerous than the 
latter and consequently of still less economic importance. 
There seems to be justification for the conclusion that, without 
man taking a hand by eliminating the main propagating opportuni- 
ties, no natural enemy of the moth will ever render it harmless. With 
human aid these agents will accomplish all that can be reasonably 
expected of them, i. e., the elimination of the ravages in rationally 
managed woodlands. 
HABITAT AND HOST TREES. 
Open, sunny stands of timber are those most affected by the Zim- 
merman pine moth. Slashings, on which reproduction has reached a 
height of 10 feet or more, having a scattered stand of mature trees, 
which were left standing to reseed the area or on account of being 
unfit for logs, invariably contain the greatest amount of pine-moth 
injury. It appears to be an absolute necessity to the insects' exist- 
ence in a locality stocked with second growth, that the stand contain 
some of these specimens, which constitute brood trees for this insect. 
Where the mature timber has been cut clean over quite large areas, 
so that the chance for influx from without is remote, the insect does 
no damage, even though the ground may be stocked with an ideal 
i Determined by S. A. Rohwer. 
