THE 
AMERICAN NATURALIST. 

Vor. XXXIX. December, 1905. No. 468. 

ECOLOGY OF THE WILLOW CONE GALL. 
ROY L. HEINDEL. 
AMONG the numerous galls to be found everywhere, the cone 
galls of the willows are very common forms. A little has been 
done toward their knowledge by Walsh, who has dealt more par- 
ticularly with descriptions of the galls and their makers and has 
done little more than make casual mention of ecological rela- 
tions. An examination of the galls in fall or winter shows them 
to be the abiding place of the larvae of a goodly number of 
insects. Walsh says: “Nothing gives us a better idea of the 
prodigious exuberance of insect life, and of the manner in which 
one insect is often dependent upon another for its very exist- 
ence, than to count up the species which haunt, either habitually 
or occasionally, one of these willow-galls, and live either upon 
the substance of the gall itself or upon the bodies of other 
insects that live upon the substance of the gall." 
In the following pages will be discussed, first, the galls them- 
selves, second, the gall makers, and third, the guests and para- 
sites that inhabit the galls. 
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