GALL-APHIDES. 



393 



new colonies; and during their migrations, attract 

 the attention of the most incurious by the singularity 

 of their appearance.* 



Galh produced on the leaves and leaf-stalhs of the Poplar hy 

 Eriosoma populi, with the various for vis of the insects, rumged, not 

 ■winged, and covered xuith vjool. 



On the black poplar there may be found, later in 

 the season than the preceding, a gall of a very dif- 

 ferent form, though, like the other, it is ibr the most 

 part on the leaf- stalk. The latter sort of galls are 

 of a spiral form; and though they are closed, they 

 open upon slight pressure, and appear to be formed 

 of two laminae, twisted so as to unite. It is at this 



J. R. 



