Insect Architecture. 



resembling a little wooden -ball of a yellowish colour, but 

 internally of a soft, spongy texture. The latter substance, 

 however, encloses a small hard gall, which is the immediate 

 residence of the included insect. Galls of this description 

 are often found in clusters of from two to seven, near the 

 extremity of a branch, not incorporated, however, but dis- 

 tinctly separate. 



We have obtained a fly very similar to this from a very 

 common gall, which is formed on the branches of the 

 willow. Like the one-celled galls just described, this is of 

 a hard, ligneous structure, and forms an irregular protuber- 



Woody Gall on a Willow branch, drawn from a specimen. 



ance, sometimes at the extremity, and sometimes on the 

 body, of a branch. But instead .of one, this has a consider- 

 able number of cells, irregularly distributed through its 

 substance. The structure is somewhat spongy, but fibrous ; 

 and externally the bark is smoother than that of the branch 

 upon which it grows. (J. E.) 



The currant-galls (as the French call them) of the oak are 

 exactly similar, when formed on the leaves, to those which 

 we have first described as produced on the leaves of the 

 willow and other trees. But the name of currant-gall seems 

 still more appropriate to an excrescence which grows on the 

 catkins of the oak, giving them very much the appearance of 

 a straggling branch of currants or bird-cherries. The galls 



