﻿KEYS 
  FOR 
  THE 
  DETERMINATION 
  OF 
  APHIDS. 
  27 
  

  

  7 
  (6). 
  Spur 
  of 
  6th 
  joint 
  of 
  antennae 
  longer 
  than 
  3rd 
  joint 
  ; 
  antennae 
  of 
  vivi- 
  

  

  parous 
  00. 
  longer 
  than 
  body, 
  even 
  in 
  normal 
  females 
  attaining 
  eleven- 
  

   twelfths 
  to 
  eighteen-nineteenths 
  of 
  the 
  body 
  length 
  ; 
  at 
  side 
  of 
  Cauda 
  

   4-6 
  bristly 
  hairs. 
  

  

  8 
  (9). 
  Body 
  of 
  apterous 
  females 
  3 
  mm. 
  and 
  more 
  ; 
  spur 
  of 
  6th 
  joint 
  of 
  antennae 
  

  

  considerably 
  longer 
  than 
  3rd 
  joint 
  4. 
  gramineamm, 
  Mordv. 
  

  

  9 
  (8). 
  Body 
  l|-2mm. 
  ; 
  insects 
  very 
  delicate, 
  semi-transparent; 
  spur 
  of 
  6th 
  

  

  joint 
  of 
  antennae 
  only 
  very 
  slightly 
  longer 
  than 
  3rd 
  joint 
  

  

  A. 
  graminum, 
  Theo. 
  

  

  10 
  (5). 
  Cornicles 
  (brown 
  or 
  dark 
  brown) 
  strongly 
  dilated 
  almost 
  in 
  the 
  middle. 
  

  

  11 
  (18). 
  Antennal 
  tubercles 
  divergent 
  . 
  . 
  . 
  . 
  Genus 
  Rhopalosiphum 
  , 
  Koch. 
  

  

  12 
  (15). 
  Apterous 
  viviparous 
  ?$ 
  yellowish 
  ; 
  spur 
  of 
  last 
  joint 
  of 
  antennae 
  almost 
  

  

  as 
  long 
  as 
  3rd 
  joint 
  ; 
  3rd 
  joint 
  in 
  apterous 
  viviparous 
  $$ 
  without 
  

   rhinaria. 
  

  

  13 
  (14). 
  Fourth 
  joint 
  of 
  antennae 
  one-fifth 
  to 
  two-fifths 
  as 
  long 
  again 
  as 
  5th 
  ; 
  

  

  apterous 
  viviparous 
  $$ 
  light 
  sulphur-yellow 
  or 
  greenish-yellow; 
  

   cornicles 
  much 
  shorter 
  than 
  3rd 
  joint 
  of 
  antennae 
  (half 
  as 
  long 
  in 
  alate 
  

   viviparous 
  $$). 
  In 
  the 
  summer 
  on 
  leaves 
  of 
  Phalaris 
  arundinacea 
  

   (Mordvilko, 
  1911) 
  and 
  Glycena 
  fluitans 
  (Boerner, 
  1913); 
  Europe 
  .. 
  

  

  Rh. 
  lonicerae, 
  Siebold. 
  

  

  14 
  (13). 
  Fourth 
  joint 
  of 
  antennae 
  only 
  slightly 
  exceeding 
  5th, 
  sometimes 
  equal 
  

  

  to 
  it 
  ; 
  apterous 
  viviparous 
  ?$ 
  cadmium-yellow, 
  their 
  cornicles 
  usually 
  

   longer 
  than 
  3rd 
  joint 
  of 
  antennae, 
  those 
  of 
  alatae 
  slightly 
  shorter. 
  

   In 
  summer 
  on 
  leaves 
  of 
  Elymus 
  canadensis, 
  E. 
  virginicus 
  and 
  Dadylis 
  

   glomerata 
  ; 
  North 
  America 
  . 
  . 
  Rh. 
  davisi, 
  sp. 
  n. 
  (Rh. 
  howardi, 
  Davis). 
  

  

  15 
  (12). 
  Apterous 
  viviparous 
  $? 
  dark 
  green 
  or 
  pale 
  brown 
  ; 
  spur 
  of 
  last 
  joint 
  more 
  

  

  or 
  less 
  exceeding 
  length 
  of 
  3rd 
  joint. 
  

  

  16 
  (17). 
  Fourth 
  joint 
  of 
  antennae 
  slightly 
  shorter 
  than 
  5th 
  ; 
  spur 
  of 
  6th 
  lf-lf 
  

  

  times 
  as 
  long 
  as 
  3rd 
  joint 
  ; 
  cornicles 
  twice 
  as 
  long 
  as 
  cauda, 
  in 
  apterous 
  

   viviparous 
  $? 
  almost 
  equal 
  in 
  length 
  to 
  3rd 
  joint. 
  On 
  Panicularia 
  

   (Glyceria) 
  nervata 
  ; 
  N. 
  America 
  . 
  . 
  . 
  . 
  Rh. 
  howardi, 
  Wilson. 
  

  

  17 
  (16). 
  Fourth 
  joint 
  of 
  antennae 
  If- 
  times 
  as 
  long 
  as 
  5th; 
  spur 
  of 
  6th 
  joint 
  

  

  1 
  1 
  times 
  as 
  long 
  as 
  3rd 
  ; 
  cornicles 
  2|-3 
  times 
  as 
  long 
  as 
  cauda, 
  slightly 
  

   shorter 
  than 
  3rd 
  joint 
  of 
  antennae. 
  On 
  roots 
  of 
  Dadylis 
  glomerata 
  ; 
  

   N. 
  America 
  . 
  . 
  Rh. 
  subterrans, 
  Wilson. 
  

  

  18 
  (11). 
  Tubercles 
  of 
  antennae 
  broad 
  and 
  low, 
  their 
  internal 
  edges 
  parallel, 
  or 
  

  

  slightly 
  projecting 
  inwards 
  at 
  the 
  apex 
  . 
  . 
  Genus 
  Myzus, 
  Pass., 
  

  

  subgenus 
  Rhopalomyzus, 
  n. 
  

  

  Apterous 
  and 
  alate 
  viviparous 
  ?2 
  dark 
  brown 
  or 
  brownish 
  

  

  black 
  ; 
  lateral 
  tubercles 
  on 
  prothorax 
  feeble 
  or 
  absent. 
  On 
  Poa 
  

  

  pratensis; 
  N.America 
  M. 
  poae, 
  Gillette. 
  

  

  19 
  (2). 
  Cornicles 
  considerably 
  shorter 
  than 
  cauda. 
  

  

  20 
  (21). 
  Cornicles 
  short, 
  cylindrical, 
  much 
  longer 
  than 
  broad 
  ; 
  frontal 
  furrow 
  

  

  distinct, 
  especially 
  in 
  alate 
  individuals 
  . 
  . 
  Genus 
  Hayhurstia, 
  n. 
  

  

  This 
  genus 
  contains 
  only 
  one 
  species, 
  H. 
  dactylidis, 
  Hayhurst, 
  

   living 
  on 
  Dadylis 
  glomerata 
  in 
  N. 
  America. 
  

  

  21 
  (20). 
  Cornicles 
  rudimentary, 
  about 
  as 
  long 
  as 
  their 
  basal 
  width 
  ; 
  body 
  long 
  

  

  and 
  narrow 
  ; 
  the 
  species 
  live 
  mostly 
  in 
  rolled-up 
  leaves 
  of 
  Graminaceae 
  

   and 
  some 
  Caryophilaceae 
  (Stellar 
  ia 
  holostea 
  ; 
  Lychnis 
  sp.), 
  more 
  

   seldom 
  free 
  on 
  leaves 
  of 
  Graminaceae 
  (along 
  central 
  vein) 
  

  

  Genus 
  Br 
  achy 
  coins, 
  Buckton. 
  

  

  