NO. 34. J HEMIPTERA OF CONNECTICUT: APHIDIDAE. 299 



Hyalopterus Koch. 



H. arundinis (Fabricius). Aphis arundinis Fabricius. Aphis 

 pruni Fabricius. 



Syst. Ent, 734, 1775. 



This species migrates between plum and reed grass. For 

 description and figures see Patch (1914b). Also see Gillette and 

 Bragg (1910). 



On European plum. 



New Haven, July, 1901 (W. E. B.). 



Hyadaphis, Liosomaphis, Rhopalosiphum and Siphocoryne. 



The species of this group are so woefully tangled as to generic 

 synonymy and are so closely affiliated by connecting forms, that 

 it is easier to key them together than to attempt to separate them 

 on generic characters. 



Key to Species. 



1. Hind wing not extraordinary 2 



Hind wing minute sef otinae 



2. Species developing on vegetation other than grasses for at least part 



of the annual cycle 3 



Species developing on grasses (Family Gramineae) for at least a 

 part of the annual cycle. Cornicle weakly swollen, with distinct 

 constriction before flange prunifoliae (avenae) 



3. Species developing on one or more plants of the family Rosaceae 



for at least a part of the annual cycle 4 



Species developing on vegetation other than Gramineae and Rosa- 

 ceae for at least a part of the annual cycle 5 



4. Dark brown or wine-colored species on Primus ..... .nymphaeae 



Delicate green or yellowish species commonest on Pyrus. Cor- 

 nicle weakly swollen with distinct constriction before flange . . . 



prunifoliae (avenae) 



5. Caudal horn present 6 



No caudal horn 8 



6. Filament of vi shorter than iv + v 7 



Filament of antenna! segment vi longer than iv -f- v. Species on 



Salix or various genera of the Umbelliferae pastinaceae 



7. Antennal segment iv without sensoria. Species on Salix or various 



genera of the Umbelliferae capreae 



IV with sensoria. Species on Umbelliferae .cicutae 



8. Species which may develop on Umbelliferae for at least part of 



the annual cycle 



Species either never reported from Umbelliferae or with other 

 host plants as well • 10 



9. Antenna of alate female rather thickly set with tuberculate sen- 



soria. General color pale green. Cauda of apterous form large, 



long and broad xylostei 



Antenna of alate female with secondary sensoria usually confined 

 to more or less crowded and irregular row on segment iii. Gen- 

 eral color brown, wine or if green then not pale. Cauda of 



apterous form not unusual nymphaeae 



10. Filament of vi distinctly longer than base 11 



