BULLETIN No. 213. 



APHID PESTS OF ^lAIXE. PART IL* 



Edith M. Patch. 

 WILLOW FA^IILY. 



It is interesting to note that the aphides attacking willows 

 and poplars are restricted to comparatively few genera. Many 

 of the species are troublesome on shade and ornamental trees. 

 The complete life cycle of certain gall forming species of the 

 poplar is not yet known, but with Pemphigus betae (Gillette 

 1912 ) traced to the cottonwcod for its winter host we have a 

 stimulus for ascertaining whether the poplar serves. as "aTternate 

 host for other species of economic importance to vegetation 

 outside of the willow family itself. 



Pemphigus populimonilis Riley. The galls of this species 

 are so familiar and characteristic with their bead like rows of 

 cells each containing a single occupant, that populimonilis has 

 been free from synonymic difficulties. Fig. 47. 



Fig. 20. P. popiilimonilis. Antenna of spring migrant. 

 Fig. 21. Antenna of pupa drawn to same scale as Fig. 20. 



* Papers from the [Maine Agricultural Experiment Station : Entomol- 

 ogy Xo. 65. 



