No. 34-] HEMIPTERA OF CONNECTICUT: APHIDIDAE. 281 



Only one species has been found in New England. 

 S. americanus Baker. 

 Can. Ent., 1, 319, 1918. 



Therioaphis Walker. 



Cornicles truncate, rather constricted mesad of apex. Antennae 

 of .?ix segments without prominent hairs and armed with subcir- 

 cular or narrowly oval sensoria. Fore wing with the media twice 

 branched ; hind wing with both media and cubitus present. Pro- 

 thorax rather elongate. Anal plate deeply bifid, the lobes distinctly 

 separated at the base. Cauda knobbed and usually somewhat 

 elongate. Species often large and distinctly colored. 



Key to Species. 



1. Entire margin of wing with a rather broad dark brown band 2 



Margin of wing not so marked ononidis 



2. Antennae distinctly annulated with dark brown ; segment iii with 



10-12 oval sensoria; tips of the wing veins marked with brown 



tiliae 

 Antennae uniform yellowish or dusky; segment iii with about 4 

 subcircular sensoria; tips of wing veins not marked with brown 



bellus 



T. bellus (Walsh). Aphis hellus Walsh. 



Proc. Ent. Soc. Phila., i, 299, 1862. 

 T. ononidis (Kaltenbach). Callipterus trifolii Monell. 



Stett. Ent. Zeit., vii, 173, 1846. 

 T. tiliae (Linnaeus). Aphis tiliae Linnaeus. 



Syst. Nat., Edn. 10, 452, 1758. 



On Tilia, New Haven, 14 July, 1909 (A. I. B.). 



Subtribe Chaitophorina. 



Forms living on the foliage and twigs of trees or occasionally 

 on other plants, differing from the Callipterina in being clothed 

 with long hairs ; cornicles reduced ; oviparous forms wingless ; 

 males winged, wingless or intermediate in the same species; 

 dimorphic forms sometimes developed. 



Key to Genera. 



1. Cauda quite distinctly knobbed 2 



Cauda not knobbed but rounded 3 



2. Antennae of 5 segments Sipha, p. 285 



Antennae of 6 segments Chaitophorus, p. 281 



3. Body elongate; small dimorphic forms developed Periphyllus, p. 283 

 Body not elongate ; no dimorphic forms developed 



Neothomasia, p. 283 



Chaitophorus Koch. 

 Cornicles present, truncate, rather prominent. Antennae of six 

 segments, armed with subcircular sensoria and many slender hairs. 



