434 CLASS VIIT. 



By far the greatest number of species live above ground on branches 

 and leaves. Amongst these both winged and wingless individuals occur in 

 the same species. The winged individuals have constantly three simple 

 eyes (KALTENBACH). 



a) Wings horizontal. Abdomen without cornicles or tubercles. (An- 

 tennse short.) 



Phylloxera, BOYEK DE FONSC., HARTIG. Antennae triarticulate, 

 with last joint fusiform, elongate, emarginate, obscurely annulate. 

 Anterior wings with cubital nerve undivided. 



Vacuna V. HEYDEN, K.ALTENB. Antennae five-jointed. Anterior 

 wings with cubital nerve bifid. 



b) Wings deflected, obliquely erect above the body. 



* Cubital nerve undivided. 



Phlceopthiridium mihi, CJiermes HARTIG. (Species from genus 

 Chermes L.) Antennae short, thickish, filiform, with five joints. Feet 

 short. Abdomen without cornicles. 



Note. Chermes is a name by no means to be given to the modern genua, 

 which rejecting all the other Linnaean species, contains one alone (C. 

 Abietis) ; the diagnosis of LIKN^US himself teaches this. On this an< 

 other allied species comp. especially RATZEBURG, Forst-Ins. in. pp. 195 

 205, Tab. XII. These insects appear to be oviparous alone ; copulation 

 has not yet been seen. 



Pemphigus HARTIG. (Spec. Chermes BURM.) 

 Tetranewra HARTIG. (Antennae with six joints.) 



* Cubital nerve sending off one or two branches. 



Schizonewra HARTIG, KALTENB., Myzoxylus BLOT (Eriosoma 

 LEACH, in part). Cubital nerve bifid. Antennae short, sex-articulate 

 Cornicles of abdomen none or obsolete. 



Sp. Aphis lanigera HAUSMANN, Eriosoma mali LEACH, &c. 



Lachnus ILLIG., BURM. Cubital nerve trifid. Antennae sex-articu- 

 late, shorter than body. Feet long. Short tubercles alone ir 

 abdomen, in place of cornicles. Feet, especially the posterior, long 

 Rostrum sometimes very long. 



Sp. Lachnus fagi, Aphis fagi L., R^AUM. Ins. in. PL 26, figs. 1^-6. Th 

 abdomen of this species J'" in size is covered with very long white wool 

 it looks like a bit of white flue ; this species is very often seen on beeche 

 in the groves at the Hague. 



Aphis ILLIG., BURM. Cubital nerve bifid. Antennae sept-articulate 

 longer than body. Feet long. Abdomen with two cornicles. 



