76 



MAINE AGRICUIvTURAL EXPERIMENT STATION. I913. 



were taken but no stem mothers in' these collections. The 

 deserted galls are frequently appropriated by colonies of 

 ChaitopJiorus. 



Pemphigus populiconduplifolius Cowen. The galls of this 

 species resembles that of gravicornis closely. Fig. 52. Some- 

 times galls of this . species instead of being folded along the 

 midrib are all on one side of the midrib in which case they are 

 elevated above the level of the surface, and like those of gravi- 

 cornis the ventral surface of the leaves forms the inside of the 

 gall. Galls are pale green tinged with red and have a swollen 

 appearance. The terminal leaves are those ordinarily attacked. 



. Fig. 24. P. populiconduplifolius. Wax gland areas of stem- 

 mother. 



Apterous viviparous female, — Stem mother. The wax gland 

 areas of this form are shown in Fig. 24 and the antenna in 

 Fig. 26. This insect is globular, dark greenish blue and woolly. 



Winged viviparous form, — spring migrant. The antenna of 

 this form is shown in Fig. 25 and the wing in Fig. 46 c. 



Fig. 25. P. populiconduplifolius. Antenna of spring migrant. 

 Fig. 26. Antenna, of stem-mother. 



