138 



ECONOMIC ENTOMOLOGY 



Fig. 

 aphids: 

 daphis. 



HH. Frontal tubercles without the promi- 

 nent tooth-like projection; cauda 

 more or less sickle shaped. — Myzus. 

 GG. First antenna! segment not conspicuously 

 gibbous on inner side. 

 H. Head with distinct and more or less 

 prominent frontal tubercles. 

 I. Cornicles clavate; antennae sel- 

 dom longer than body; cauda 

 tapering and knobbed. — Rhopalo- 

 siphum. 

 II. Cornicles cylindrical or incon- 

 spicuously swollen; antennae usu- 

 ally longer than body; cauda 

 ensiform. — Macrosiphum. 

 HH. Head with frontal tubercles absent or 

 slight. 

 I. Cornicles distinctly clavate. — 



Siphocoryne (Hyadaphis), 

 II. Cornicles usually cylindrical and 

 of moderate length; if clavate 

 they are only slightly swollen 

 and quite small. 

 J. Cornicles very short, much 

 shorter than cauda, slightly 

 swollen; beak short; antenna: 

 shorter than body. — Hyalop- 

 terus. 

 J J. Not as above, i.e., cornicles 

 moderately long, usually 

 longer than cauda, cylindri- 

 cal; antennae usually as long 

 as or only slightly shorter 

 than body. — Aphis. 

 BB. Media of fore wings once forked or simple. 

 C. Media simple. 



D. Hind wings with two oblique veins. — Pemphigus. 

 DD. Hind wings with but one oblique vein. 



E. Antennae 6-segmented. — Tetraneura. 

 EE. Antennae s-segmented. — Hamamelistes. 

 EEE. Antennae 3-segmented. — Hormaphis. 

 CC. Media once forked. 



D. Cornicles present, an Aphis-like species. — Toxoplera. 

 DD. Cornicles vestigial or wanting. 



E. Hind wings with two oblique veins. — Eriosoma. 

 EE. Hind wings with one oblique vein. — Colopha. 



90. — Front of head of 

 a, Chaitophorus; b, Hya- 



