126 
The Ohio Naturalist. 
[Vol. IV, No. 6, 
The mouthparts of a number of larvae were examined (Figs, 
loi, 102 j, and all were practically the same; salivary or other 
gland structures could not be demonstrated. 
I am inclined to believe that the Cecidoni3-id galls are due to 
purelj" mechanical stimuli and that the great variations are due 
to the different tissues upon which the larvae feed. 
Mr. W. A. Cannon,* in discussing a Cecidoniyid gall on the 
Montere>' pine, says that the “larvae take their food only by 
absorption through the surface of the body,’’ also that “ there is 
no indication that the h3-pertroph>' is either caused or affected by 
any substance deposited with the eggs.” 
3. HYMENOPTERA. 
\Ye now come to the galls of greatest complexit3- and also to 
those with which we have the greatest difficult3'. These galls are 
so ver3" generall3' infested with parasites and inquilines that it is 
difficult to decide which larva is the true gall producer. 
A careful study of these shows that the in.sects have a very 
strong pair of mandibles (Figs. 103 to 108), each working upon 
two pivotal points. Some of these mandibles appear to have an 
opening at the tip (^Figs. 104, 105), and some showed what 
appeared to be .sacs or glands at the base (Figs. 104, io6b). In 
one case at least (Fig. 104) these glandular sacs appeared to be 
connected with the opening. The question that naturally pre- 
sents itself is, are these openings for the purpose of pouring out 
a fluid or are the3’ suctorial as in the case of Chr3’sopa and other 
families? In onl3’ two species was it possible to demonstrate 
these structures. Some light is thrown upon this b3’ Part VIII, 
in which it was shown that the cell walls of the inner or nutritive 
zones were not destroyed, but that the contents of the cells were 
removed, causing them to shrivel. 
The teeth of the mandibles are never on the same plane and 
the mandibles become more and more chitinous as the larvae 
approach maturit3’. The strength of the mandibles appears to 
depend upon the densit3’ of the tissue through which the insect 
works its way to the out.side In A. inanis (104) and A. con- 
fluentus (Fig. 105) the .strength of the mandibles is practically 
the .same and the character of the galls ver3' similar. In D. sim- 
inis (Figs. io6a, b) the mandibles are stronger and the tissues of 
the gall correspondingh’ denser. C. petiolicola ( Fig. 103) is by 
far the strongest of those studied, and the tissues through which 
the insect mu.st work its wa3^ the dense.st of the leaf galls (Fig. 
124). 
A stud3' was made of the larvae from galls of C. papillatus. 
This is a small, rather dense leaf gall. Larvae of two species 
* Cannon. W. A. “The Gall of the Monterey Pine.’’ The American .XaluralisI, Vol. 
XXXIV, No. 406 (Oct., 1900), p. 801. 
