OF WASHINGTON. 143 
NOTES ON SCOLYTID LARV^ AND THEIR MOUTH 
PARTS. 
BY A. D. HOPKINS, PH. D. 
In the study of forest insects, and especially in that relating 
to experimental work with girdled and felled trap trees, it 
is of the greatest importance to be able to identify the species 
from the immature stages, yet the published results of accurate 
work on the larvae of American Scoly tidae and other important 
groups of insect enemies and friends of forest trees and 
their products, is so meager that it is practically of no use 
to us in our field work. Therefore, it has been necessary to 
take up the study of the larvae of the more important species, 
with a view of preparing tables of characters, for their identi- 
fication. 
The identification of good specific characters of the adults 
to tabulate for their identification has given me so much trouble 
and occupied so much time that heretofore it has seemed a 
hopeless task to undertake systematic work on the larvae and 
pupae, but, in working up material for a monograph on the 
genus Dendroctonus, it became necessary to study the larva, 
and the results have been so satisfactory that the prospect for 
success in future studies of the larvae of other genera and 
groups is quite encouraging. 
The Scolytid larva is of the simple legless type, with slight 
variation in general appearance ; the body segments are rarely 
with chitinous plates, and, while the living examples present 
some distinctive characters of form and pubescence, these are 
obscure and usually lost in alcoholic specimens. Therefore, 
it was realized that any character, to be of special value, must 
be found in such chitinous parts as would be readily preserved 
in alcohol, in cast skins in the pupal chambers, and in dry 
specimens. This led me to give special attention to the 
head and mouthparts and "other chitinous parts of the body, 
and has resulted in the determination of some very good char- 
acters in Dendroctonus and other larvae. Their value in 
classifying the species of the genus into natural divisions 
and series was indicated when, upon tabulating them, I found 
that the larval characters referred the species into practically 
the same positions as had the imago characters, and, if any- 
thing, had indicated even better natural affinities. This was 
also verified by the secondary sexual and purjal characters 
and the characteristics of work and habits, all of which have 
been tabulated. 
