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CHAPTER XXVI. 
PARASITIC NESTS— {concluded). 
The Oak-tree, and its aptitude for nourishing Galls — Compound Galls, or 
one Gall within another — The Sensitive Gall of Carolina — Galls and the 
Insects which caused them — Colours of Galls — Whence derived — The Galls 
of various trees and plants — The Cymps parasites upon an insect — Galls pro- 
duced by other insects — Mr. Rennie’s account of the Beetle Gall of the 
Hawthorn — The Beetle Gall of the Thistle— Dipterous Gall-makers 
— Animal Galls — The Chigoe and its habits — Its curious egg-sac — Difficulty 
of extirpating it — The penalty of negligence — The Breeze Flies and their 
habitations — Wurbles and their origin — Their influence upon cattle — The 
Clerus and its ravages among the hives — The Drilus, its remarkable form 
and the difference between the sexes — The curious habitation which it 
makes. 
The reader cannot but notice the singular aptitude possessed 
by the oak-tree for nourishing galls. No part of the tree seems 
to escape the presence of a gall of some sort, diverting its vital 
powers into other channels. The tree, however, does not appear 
to suffer from them, and it is just possible that they may be 
useful to it. The leaves are studded with galls, and so are their 
stems. The branches are covered with galls of various shapes, 
sizes, and colours, some bright, smooth, and softly coloured, like 
ripe fruit, others hard, harsh, spiny, and rough, as if the very 
essence of the gnarled branches had been concentrated in them. 
There are galls upon the flowers, galls upon the trunk, and even 
galls upon the root. 
Some oak-galls may be called compound galls. M. Bose 
mentions a small gall which is found upon the American oak. 
It is not larger than a pea, and if shaken is found to contain 
some hard substance loosely lodged in its interior. When the 
gall is cut open, a very curious state of things is seen. The 
walls are very thin, so that in spite of the small dimensions, the 
