Pemphigus spirothecae. 



These galls were at one time thought to be but a variety of 

 those caused by Pempliigus bursarius. Cameron, however, has 

 by a comparison of the females shown that they are caused by 

 a different species of Pemphigus. The hybernation of the 

 foundress is passed in the ground, whence, at the return 

 of spring, she emerges. She then proceeds to puncture with 

 her rostrum either of the flattened sides of the petiole for the 

 purpose of obtaining nourishment. This treatment causes the 

 petiole to bulge in a direction away from her attacks, and at the 

 same time it broadens. Very soon it begins to curve in a spiral 

 manner ; this continues until the edges are closely attached, 

 but they do not anastomose. For a time this spiral formation 

 is moderately elastic, and with care may be opened or even 

 paritially unrolled. When near maturity and the emersion of 

 the imagines it will yield to the strain and separate. The shape 

 of a mature specimen of this gall is less variable than that of 

 the preceding species, and so distinct is it in all stages of its 

 development that it is not possible to be mistaken. 



The illustration is of specimens gathered at Hastings by 

 the author. 



