﻿— 
  8i 
  — 
  

  

  but 
  their 
  rate 
  of 
  multiplication 
  is 
  enormous, 
  and 
  under 
  especially 
  favor- 
  

   able 
  circumstances 
  almost 
  any 
  species 
  may 
  rapidly 
  become 
  so 
  abundant 
  

   locally 
  as 
  practically 
  to 
  destroy 
  its 
  food 
  plant 
  for 
  the 
  time 
  being. 
  Most 
  

   of 
  the 
  species 
  hatch 
  from 
  eggs 
  in 
  the 
  spring, 
  all 
  of 
  this 
  first 
  generation 
  

   being 
  females 
  capable 
  of 
  reproducing 
  without 
  copulation, 
  and 
  giving 
  

   birth 
  to 
  living 
  young 
  as 
  soon 
  as 
  they 
  themselves 
  become 
  adult. 
  Several 
  

   generations 
  are 
  ordinarily 
  brought 
  forth 
  in 
  like 
  manner 
  in 
  a 
  single 
  

   season, 
  only 
  the 
  last 
  of 
  which 
  is 
  composed 
  of 
  both 
  males 
  and 
  females, 
  

   and 
  these 
  produce 
  the 
  eggs 
  by 
  means 
  of 
  which 
  the 
  species 
  is 
  carried 
  past 
  

   the 
  winter. 
  

  

  These 
  insects 
  are 
  commonly 
  kept 
  in 
  check 
  by 
  their 
  natural 
  enemies, 
  

   the 
  ladybugs, 
  the 
  lace-wing 
  flies, 
  and 
  a 
  number 
  of 
  rapidly-breeding 
  par- 
  

   asites. 
  It 
  is 
  only 
  occasionally, 
  consequently, 
  that 
  remedial 
  measures 
  

   are 
  likely 
  to 
  be 
  necessary. 
  In 
  that 
  case 
  tobacco-water, 
  kerosene 
  emul- 
  

   sion, 
  or 
  a 
  mechanical 
  mixture 
  of 
  water 
  and 
  kerosene 
  should 
  be 
  used, 
  as 
  

   prescribed 
  for 
  leaf-hoppers 
  on 
  page 
  64. 
  The 
  arsenical 
  poisons, 
  Lon 
  

   don 
  purple, 
  Paris 
  green, 
  and 
  the 
  like, 
  are 
  inadmissible, 
  since 
  they 
  do 
  

   not 
  take 
  effect 
  on 
  the 
  plant-louse, 
  but 
  will 
  kill 
  many 
  of 
  its 
  insect 
  enemies. 
  

   They 
  are 
  thus 
  likely 
  to 
  increase 
  the 
  danger 
  instead 
  of 
  diminishing 
  it. 
  

  

  The 
  Melon 
  Aphis. 
  

  

  Aphis 
  gossypii 
  Glover. 
  

  

  (^Aphis 
  cucnineris 
  Forbes. 
  ) 
  

  

  This 
  is 
  the 
  common 
  melon 
  and 
  cucumber 
  aphis 
  of 
  the 
  central 
  

   United 
  States. 
  It 
  abounds 
  on 
  a 
  large 
  variety 
  of 
  plants 
  throughout 
  all 
  

   the 
  United 
  States 
  except 
  the 
  extreme 
  northern 
  part, 
  and 
  also 
  in 
  Mexico, 
  

   the 
  West 
  Indies, 
  and 
  Australia. 
  It 
  was 
  found 
  in 
  Nebraska 
  by 
  Mr. 
  T. 
  \. 
  

   Williams 
  in 
  1890 
  breeding 
  abundantly 
  on 
  beets 
  in 
  the 
  vicinity 
  of 
  infested 
  

   cucumber 
  vines. 
  An 
  injury 
  attributed 
  to 
  ants, 
  reported 
  from 
  Nebraska, 
  

   was 
  perhaps 
  due 
  to 
  this 
  species. 
  Its 
  leading 
  food 
  plants 
  are 
  melons, 
  

   cucumbers, 
  and 
  other 
  vines 
  of 
  the 
  cucumber 
  family, 
  crops 
  of 
  which 
  

   it 
  sometimes 
  almost 
  destroys. 
  It 
  is 
  also 
  abundant 
  on 
  cotton, 
  beans, 
  

   pear-trees, 
  European 
  dogwood, 
  orange-trees, 
  hothouse 
  plants, 
  and 
  a 
  

   large 
  number 
  of 
  the 
  commonest 
  weeds, 
  including 
  purslane, 
  shepherd's- 
  

   purse, 
  pepper-grass, 
  pigweed 
  (^Amara?iitis), 
  lamb's-quarters 
  {Chenopo- 
  

   diuni), 
  plantain, 
  dock, 
  dandelion, 
  Jamestown 
  weed 
  (^Datura), 
  etc.; 
  

   also, 
  in 
  lesser 
  numbers, 
  on 
  hops, 
  spinach, 
  tomato, 
  red 
  clover, 
  and 
  

   burdock. 
  

  

  The 
  eggs 
  have 
  been 
  found 
  on 
  purslane, 
  and 
  are 
  at 
  first 
  yellowish 
  or 
  

   greenish, 
  but 
  soon 
  become 
  jet-black. 
  The 
  color 
  of 
  the 
  wingless 
  lice 
  

   varies 
  all 
  the 
  way 
  from 
  yellow 
  or 
  green 
  to 
  black; 
  the 
  antennae, 
  about 
  

   half 
  as 
  long 
  as 
  the 
  body, 
  are 
  mostly 
  pale, 
  and 
  the 
  honey-tubes 
  are 
  black. 
  

   The 
  winged 
  ones 
  are 
  similarly 
  varied, 
  but 
  are 
  never 
  entirely 
  black; 
  the 
  

  

  