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CHAPTER XXVI. 



PARASITIC NESTS -{coTfcluded). 



The Oak-tree, and its aptitude for nourishing Galls— Compound Gall6, 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 Cynips 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-makeks 

 —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. Bosc 

 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 ver>' thin, so that in spite of the small dimensions, the 



