140 CONNECTICUT GEOL. AND NAT. HIST. SURVEY. [BuU. 



segments indistinct toward tip, and saw-guides, black; saw- 

 guides broad and robust, scarcely tapering, rounded at tip; 

 male differs in having more of black on head, thorax for 

 the most part, and dorsum of abdomen, black. Length 



4-5.5 mm pomum 



Head in female with ridges about ocellar basin well defined and 

 thick ; clypeus deeply and narrowly emarginate, lobes rounded ; 

 head and thorax strongly punctate; frontal crest large, 

 slightly notched; body ferruginous, with antennae, large 

 spot including ocelli, stripe on anterior lobe of mesonotum, 

 stripe in front of scutellum, most of metanotum, and dor- 

 sum of abdomen except at sides and at apex, brownish 

 black. Male differs in having ocellar basin less distinctly 

 defined. Length 4-5 mm desmodioides 



°P. atra Marlatt. 



P. hyalina (Norton). Messa hyalina Norton. Larva makes 

 galls on Salijv fragilis. New Haven, 19 April, 1910 (B. H. W.). 

 P. terminalis Marlatt. Larva makes galls on smooth-leaved 

 willow. 



°P. rugulosa Marlatt. 



°P. robusta Marlatt. Larva folds the leaves of Populus 

 tremuloides. 



^P. placenta Norton. Nematus placenta Norton. 



°P. populi Marlatt. Larva folds the leaves of Populus 

 grandidentata. 



°P. censors Marlatt. Larva makes galls on Salix sericea. 



°P. borealis Marlatt. Larva makes galls on Salix sericea. 



°P. pectoralis Marlatt. 



°P. acuminata Marlatt. 



°P. nigrita Marlatt. 



°P. gracilis Marlatt. Larva makes galls on Salix petiolata. 



°P. pallicornis (Norton). Nematus pallicornis Norton. 

 Larva feeds on willow. 



P. pisum (Walsh). Nematus pisum Walsh. Larva makes 

 galls on Salix discolor. New Haven, 20 May, 1911 (A. B. C). 



°P. pomum (Walsh). Nematus pomum Walsh. Nematus 

 hospes Walsh. Larva makes galls on Salix cordata and dis- 

 color. 



