OAK GALLS. 517 



hard - pointed horns, much like those which arm the preceding 

 species. Indeed, the whole substance of the gall is remarkable 

 for its hard texture, for, when cut with a knife, it offers as stub- 

 born a resistance as if it were seasoned oak or elm. 



That a hymenopterous insect should be able to bore its way 

 through so hard a substance, and to make a tunnel barely wide 

 enough for the passage of its body, and nearly three quarters of 

 an inch in length, is really surprising. The insect is not a large 

 one, and resembles Cynips Kollari so closely that an inexperienced 

 observer would certainly mistake it for that insect, the distinc- 

 tions being so trifling that they can only be detected by means of 

 the microscope. 



CHAPTER XXVI. 



PARASITIC NESTS— {Continued). 



The Oak-tree, and its Aptitude for nourishing Galls. — Compound Galls, or one 

 Gall within another.— The Sensitive Gall of Carolina. — The Fungus of Wine- 

 vaults. — Galls and the Insects which caused them. — Colors of Galls. — Whence 

 derived. — The Galls of various Trees and Plants. — The Cynips parasites upon an 

 Insect. — Galls produced by other Insects. — Mr. Rennie's Account of the Beetle 

 Gall of the Hawthorn. — The Beetle Gall of the Thistle. — Dipterous Gall- 

 makers. — Leaf-miners and Galls. — Size of the Larvae of Leaf-miners. — The per- 

 fect Insect and their Beauty. — Method of displaying the Insect. — Social Leaf- 

 miners. — Dipterous Leaf-miners. — Animal Galls. — The Chigoe and its Hab- 

 its. — Its curious Egg-sac. — Difficulty of extirpating it. — The Penalty of Negli- 

 gence. — 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 can not 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 use- 

 ful to it. The leaves are studded with galls, and so are their 

 stems. The branches are covered with galls of various shapes, 

 sizes, and colors, some bright, smooth, and softly colored, 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. 



