﻿494 
  

  

  at 
  least, 
  the 
  swarming 
  occurred 
  at 
  considerable 
  distances 
  from 
  any 
  

   vegetation, 
  and 
  any 
  idea 
  that 
  the 
  insects 
  gathered 
  there 
  in 
  search 
  of 
  

   food 
  must 
  be 
  abandoned. 
  Nor 
  is 
  swarming 
  likely 
  to 
  be 
  connected 
  

   with 
  reproduction, 
  or 
  it 
  would 
  probably 
  occur 
  with 
  greater 
  regularity 
  

   and 
  exhibit 
  a 
  certain 
  periodicity. 
  The 
  author 
  suggests 
  that 
  this 
  

   phenomenon 
  may 
  be 
  connected 
  wuth 
  hibernation, 
  or 
  may 
  be 
  an 
  attempt 
  

   to 
  escape 
  from 
  enemies, 
  or 
  be 
  determined 
  by 
  failure 
  of 
  food 
  supply. 
  

   On 
  one 
  occasion 
  on 
  an 
  expedition 
  to 
  the 
  Musine 
  he 
  failed 
  to 
  find 
  a 
  

   single 
  insect 
  in 
  the 
  summer 
  of 
  the 
  same 
  year 
  in 
  the 
  April 
  of 
  which 
  he 
  

   had 
  observed 
  swarms, 
  and 
  concludes 
  that 
  the 
  swarms 
  are 
  of 
  short 
  

   duration 
  and 
  that 
  there 
  is 
  probably 
  no 
  one 
  cause 
  for 
  them. 
  Neither 
  

   is 
  the 
  swarming 
  of 
  Coccinellids 
  on 
  certain 
  plants 
  easily 
  explained, 
  

   further 
  evidence 
  on 
  these 
  points 
  being 
  much 
  needed. 
  The 
  species 
  

   which 
  exhibit 
  the 
  habit 
  in 
  the 
  greatest 
  degree 
  are 
  C. 
  7-puncata, 
  

   C. 
  b-].unctata, 
  C. 
  convergens, 
  and 
  Adalia 
  11 
  notata. 
  

  

  Davidson 
  (J.). 
  Ueber 
  die 
  Wirtpfianze 
  von 
  Ajphis 
  rumicis 
  L. 
  [The 
  

   host 
  plants 
  of 
  Aphis 
  rumicis 
  L.] 
  — 
  Zeits. 
  wissen. 
  Insektenbiol.y 
  

   Berlin, 
  x, 
  no. 
  5, 
  20th 
  May 
  1914, 
  pp. 
  189-190. 
  

  

  Experiments 
  were 
  made 
  to 
  discover 
  if 
  possible 
  the 
  host 
  plants 
  of 
  

   Aphis 
  rumicis 
  {A. 
  euonymi, 
  F.). 
  The 
  insects 
  were 
  found 
  in 
  large 
  

   numbers 
  on 
  the 
  spindle 
  tree 
  (Euonymus 
  europaeus) 
  in 
  the 
  spring; 
  

   winged 
  parthenogenetic 
  females 
  were 
  placed 
  on 
  dock 
  {Rumex 
  sangui- 
  

   neus), 
  garden-beans, 
  poppy, 
  onion, 
  beetroot, 
  sugar-beet, 
  mangel- 
  

   wurzel, 
  and 
  turnip. 
  These 
  plants 
  were 
  grown 
  in 
  pots 
  and 
  covered 
  

   with 
  gauze. 
  The 
  beans 
  were 
  without 
  exception 
  severely 
  attacked 
  ; 
  

   poppies 
  were 
  also 
  attacked 
  ; 
  beetroots, 
  sugar-beets 
  and 
  mangel-wurzels 
  

   were 
  very 
  slightly 
  attacked 
  ; 
  a 
  few 
  isolated 
  small 
  colonies 
  were 
  

   found 
  on 
  the 
  turnips, 
  and 
  none 
  at 
  all 
  on 
  the 
  onions. 
  

  

  A 
  large 
  gauze 
  tent, 
  pitched 
  in 
  the 
  open, 
  was 
  divided 
  into 
  three 
  

   sections. 
  A, 
  B, 
  and 
  C, 
  between 
  which 
  there 
  was 
  no 
  communication, 
  

   the 
  ground 
  beneath 
  the 
  tent 
  having 
  been 
  soaked 
  with 
  carbon 
  bisul- 
  

   phide 
  in 
  April. 
  In 
  section 
  A 
  the 
  following 
  plants 
  were 
  growing 
  : 
  — 
  

   bean, 
  poppy, 
  beetroot, 
  sugar-beet, 
  mangel-wurzel, 
  turnip, 
  dock, 
  water- 
  

   cress 
  and 
  onion 
  ; 
  in 
  B, 
  only 
  poppy 
  and 
  bean, 
  and 
  in 
  C, 
  dock 
  and 
  bean. 
  

   In 
  each 
  section 
  a 
  small 
  spindle 
  tree 
  infested 
  with 
  the 
  Aphids 
  was 
  

   placed, 
  and 
  the 
  migrations 
  of 
  the 
  winged 
  parthenogenetic 
  females 
  

   were 
  observed. 
  In 
  C, 
  no 
  results 
  were 
  obtained, 
  the 
  females 
  on 
  the 
  

   infected 
  Euonymus 
  giving 
  rise 
  to 
  very 
  few 
  offspring. 
  In 
  A, 
  the 
  beans 
  

   suffered 
  the 
  most 
  severely 
  and 
  then 
  the 
  poppies 
  ; 
  the 
  females 
  which 
  

   had 
  migrated 
  to 
  the 
  beans 
  migrated 
  again 
  to 
  the 
  poppies, 
  where 
  they 
  

   reproduced. 
  The 
  beetroots 
  and 
  sugar-beets 
  were 
  only 
  slightly 
  

   attacked 
  ; 
  a 
  few 
  colonies 
  were 
  observed 
  on 
  mangel- 
  w^urz 
  els 
  and 
  

   several 
  on 
  docks, 
  but 
  none 
  at 
  all 
  on 
  onions, 
  turnips 
  and 
  watercress. 
  

   In 
  B, 
  the 
  beans 
  were 
  the 
  first 
  to 
  be 
  attacked. 
  

  

  Three 
  spindle 
  trees, 
  all 
  heavily 
  infested 
  with 
  A. 
  rumicis, 
  were 
  

   observed 
  in 
  the 
  garden 
  ; 
  later 
  colonies 
  of 
  the 
  Aphids 
  were 
  found 
  on 
  

   the 
  following 
  plants 
  : 
  — 
  beans, 
  docks, 
  spinach, 
  parsnip, 
  dwarf 
  bean, 
  

   kidney-bean, 
  beetroot, 
  sugar-beet, 
  mangel-wurzel, 
  peas, 
  thistle, 
  

   shepherd's 
  purse, 
  watercress, 
  dahlia, 
  nettles, 
  Atriplex 
  horiense, 
  and 
  

   Chenopodium 
  album. 
  

  

  