﻿38 
  A. 
  K. 
  MORDVILKO. 
  

  

  0-072 
  mm. 
  ; 
  in 
  alate 
  sexuparae 
  3rd 
  joint 
  of 
  antennae 
  2*-2£ 
  times 
  

   as 
  long 
  as 
  6th 
  and 
  almost 
  twice 
  as 
  long 
  as 
  5th, 
  4th 
  joint 
  somewhat 
  

   shorter 
  than 
  6th 
  . 
  . 
  . 
  . 
  T. 
  rubra, 
  Licht. 
  (P. 
  coertdesccns, 
  Pass., 
  

  

  boyeri, 
  Mordv.). 
  

  

  5 
  (2). 
  In 
  apterous 
  viviparous 
  $£ 
  antennae 
  very 
  short, 
  5-jointed, 
  the 
  3rd 
  being 
  

  

  the 
  shortest, 
  and 
  5th 
  longest 
  ; 
  in 
  alate 
  viviparous 
  $$ 
  3rd 
  joint 
  almost 
  

   equal 
  to 
  three 
  others 
  taken 
  together. 
  X. 
  America 
  

  

  T. 
  gra 
  minis, 
  Monell 
  

  

  6 
  (1). 
  In 
  apterous 
  viviparous 
  $$ 
  tarsus 
  not 
  at 
  all 
  or 
  hardly 
  separated 
  from 
  

  

  tibia 
  ; 
  antennae 
  very 
  short, 
  4-jointed, 
  3rd 
  joint 
  somewhat 
  longer 
  

   than 
  the 
  others 
  ; 
  anal 
  tergite 
  and 
  sternite 
  equally 
  small 
  and 
  not 
  

   projecting 
  backwards 
  ; 
  in 
  alate 
  viviparous 
  $$ 
  3rd 
  joint 
  of 
  antennae 
  

   equal 
  to 
  three-quarters 
  to 
  twelve-thirteenths 
  the 
  length 
  of 
  the 
  three 
  

   remaining 
  taken 
  together, 
  the 
  last 
  three 
  joints 
  being 
  almost 
  equal 
  

   in 
  length 
  ; 
  median 
  vein 
  of 
  fore 
  wing 
  branching 
  once 
  ; 
  comparatively 
  

   small 
  species, 
  up 
  to 
  H 
  mm. 
  Migrantes 
  on 
  sedge 
  roots 
  {Carex), 
  but 
  

   in 
  N. 
  America 
  on 
  Eragrostis 
  minor 
  and 
  Panicum 
  ; 
  partly 
  hibernating 
  

   on 
  roots 
  . 
  . 
  . 
  . 
  . 
  . 
  . 
  . 
  . 
  . 
  Genus 
  Colopha, 
  Monell. 
  

  

  Here 
  belongs 
  only 
  one 
  species, 
  C. 
  compressa, 
  Koch, 
  1857 
  (ulmicola, 
  

   Fitch, 
  1859). 
  in 
  which 
  the 
  fundatrices 
  and 
  alate 
  virgines-emigrantes 
  

   develop 
  in 
  red 
  depressed 
  galls 
  between 
  the 
  veins 
  of 
  leaves 
  of 
  Ulmus 
  

   effusa 
  in 
  the 
  Palaearctic 
  and 
  U. 
  racemosa 
  in 
  the 
  Xearctic 
  region. 
  

  

  Tribe 
  Pemphigea. 
  

  

  Of 
  this 
  tribe 
  several 
  species 
  live 
  on 
  roots 
  of 
  Graminaceae, 
  apparently 
  as 
  migrantes, 
  

   but 
  their 
  connection 
  with 
  other 
  species 
  on 
  primary 
  host-plants 
  has 
  not 
  yet 
  been 
  

   completely 
  established. 
  The 
  species 
  in 
  most 
  cases 
  have 
  been 
  insufficiently 
  character- 
  

   ised 
  by 
  previous 
  authors, 
  and 
  often 
  to 
  such 
  an 
  extent 
  that 
  with 
  some 
  species 
  there 
  

   is 
  no 
  certainty 
  that 
  they 
  do 
  not 
  belong 
  to 
  another 
  tribe. 
  

  

  The 
  root 
  Aphids 
  of 
  the 
  tribe 
  Pemphigea 
  so 
  far 
  known 
  from 
  Graminaceae, 
  including 
  

   the 
  insufficiently 
  characterised 
  ones, 
  may 
  be 
  provisionally 
  distinguished 
  by 
  the 
  

   following 
  key 
  : 
  — 
  

  

  1 
  (14). 
  Antennae 
  5-jointed 
  in 
  apterous 
  viviparous 
  $? 
  from 
  roots. 
  

  

  2 
  (3). 
  All 
  joints 
  of 
  short 
  antennae 
  almost 
  equal 
  in 
  length, 
  last 
  joint 
  thicker 
  ; 
  

  

  body 
  bristly, 
  white-marmorated, 
  powdered 
  

  

  Tychea 
  setulosa, 
  Pass, 
  (nee 
  Buckton,= 
  Endeis 
  pellucida, 
  Buckt.i. 
  

  

  3 
  (2). 
  Joints 
  of 
  antennae 
  not 
  equal 
  to 
  each 
  other, 
  either 
  5th 
  or 
  3rd 
  longer 
  than 
  

  

  the 
  others. 
  

  

  4 
  (13). 
  Fifth 
  joint 
  longer 
  than 
  the 
  others 
  or 
  at 
  least 
  not 
  shorter 
  than 
  3rd. 
  

  

  5 
  (8). 
  First 
  four 
  joints 
  of 
  antennae 
  more 
  or 
  less 
  equal 
  to 
  each 
  other. 
  

  

  6 
  (7). 
  Body 
  oval, 
  pale 
  ochre 
  yellow 
  ; 
  on 
  dorsal 
  surface 
  of 
  body 
  well-developed 
  

  

  groups 
  of 
  glands, 
  from 
  which 
  is 
  secreted 
  a 
  white 
  down. 
  On 
  roots 
  of 
  

   Poa 
  annua; 
  South 
  England 
  .. 
  .. 
  Rhizobius 
  poae, 
  Buckt. 
  

  

  7 
  (6). 
  Body 
  spherical, 
  smooth, 
  yellowish 
  white, 
  slightly 
  powdered 
  ; 
  last 
  three 
  

  

  joints 
  of 
  antennae 
  more 
  or 
  less 
  equal 
  in 
  length. 
  On 
  roots 
  of 
  Carex 
  

   dioica 
  ; 
  South 
  England 
  .. 
  .. 
  .. 
  Endeis 
  formicina, 
  Buckt. 
  

  

  8 
  (5). 
  First 
  four 
  joints 
  of 
  antennae 
  not 
  equal 
  to 
  each 
  other. 
  

  

  