136 ECONOMIC ENTOMOLOGY 



Spray with lime-sulphur, whale-oil soap, kerosene emulsions, 

 miscible oils or whitewash when outdoor plants are infested. 



APHIDID^ (APHIDS OR PLANT-LICE) 



Chief Economic Gener\ (Figs. 86-94) 



\. Front wings with four oblique veins; antennae generally 6-segmented. 

 B. Media of fore wings twice forked (except Lachnus in part). 

 C. Antennas of winged female s-segmented. — Sipha. 

 CC. Antennas of winged female 6-segmented. 



D. Cornicles mammiform; filament of sixth segment of 

 antennae not developed. 



E. Fore wing with stigmal shading appearing as the 

 stigma, extending to tip of wing. Large aphids 

 occurring commonly on Quercus, Tilia, and Plalanus. 

 — Longistigma. 

 EE. Venation normal, except in Lachnus where media is 

 sometimes unbranched or only once forked. Occur- 

 ring usually on conifers, never on Tilia or Platanus. 

 F. Flocculent species. Never on conifers. — Phyl- 



lapliis. 

 FF. Not conspicuously flocculent as in F. Occur- 

 ring on conifers. — Lachnus. 

 DD. Cornicles variously shaped, seldom mammiform but if so 

 the filament of sixth antennal segment developed. 



E. Large aphids with cornicles usually vasiform, body 

 and appendages hirsute. Occurring on Populus and 

 Salix. — Pterocomma. 

 EE. Not as above. 



F. Cornicles short or wanting, usually tuberculate; 

 Cauda bluntly rounded or knobbed. 

 G. Cornicles appear as mere rings; wings held 

 horizontal when at rest. — Monellia. 

 GG. Cornicles usually distinct; wings held 

 slanting or roof-shaped over back when at 

 rest. 

 H. Body and appendages hirsute in 

 which respect it approaches Ptero- 

 comma but smaller and mostly leaf- 

 feeders; hairs not knobbed; antennae 

 noticeably shorter than body; gre- 

 garious on host. — Chaitophorus. 

 HH. Body not conspicuously hirsute; 

 antennae varying in length often 



