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  on 
  the 
  surface 
  of 
  the 
  infested 
  leaf, 
  each 
  speck 
  representing 
  a 
  point 
  of 
  

   plant 
  tissue 
  deadened 
  by 
  the 
  withdrawal 
  of 
  its 
  living 
  substance. 
  A 
  mul- 
  

   tiplication 
  of 
  these 
  dead 
  blotches 
  interferes 
  with 
  the 
  performance 
  of 
  

   the 
  function 
  of 
  the 
  leaf, 
  checks 
  the 
  growth 
  of 
  the 
  plant, 
  and, 
  if 
  exces- 
  

   sive, 
  may 
  cause 
  parts 
  of 
  it 
  to 
  die. 
  Sometimes 
  on 
  the 
  young 
  leaf 
  the 
  

   injurious 
  effect 
  extends 
  some 
  distance 
  beyond 
  the 
  puncture, 
  as 
  shown 
  

   by 
  a 
  discolored 
  stripe 
  extending 
  towards 
  the 
  tip 
  of 
  the 
  leaf. 
  The 
  attack 
  

   begins 
  in 
  early 
  spring, 
  and 
  is 
  continued 
  without 
  cessation 
  until 
  fall, 
  the 
  

   numbers 
  of 
  these 
  insects 
  increasing 
  with 
  the 
  advance 
  of 
  the 
  season 
  as 
  

   the 
  various 
  species 
  breed 
  in 
  successive 
  generations. 
  

  

  The 
  eggs 
  are 
  laid, 
  as 
  a 
  rule, 
  in 
  the 
  stems 
  and 
  leaves 
  of 
  plants 
  or 
  

   between 
  the 
  leaf-sheaths 
  and 
  stems 
  of 
  grass-like 
  plants 
  which 
  have 
  en- 
  

   sheathing 
  leaves. 
  In 
  an 
  outdoor 
  breeding-cage 
  containing 
  blue-grass 
  

   and 
  timothy 
  a 
  large 
  number 
  of 
  grass 
  leaf-hoppers 
  in 
  considerable 
  variety 
  

   were 
  placed 
  September 
  lo. 
  From 
  September 
  19 
  to 
  October 
  22 
  numer- 
  

   ous 
  minute 
  eggs 
  were 
  found 
  inserted 
  side 
  by 
  side 
  in 
  a 
  symmetrical 
  row 
  

   in 
  the 
  sheaths 
  of 
  the 
  timothy. 
  They 
  were 
  slightly 
  curved, 
  slender- 
  

   elliptical 
  in 
  form, 
  at 
  first 
  translucent 
  yellowish 
  and 
  later 
  reddish. 
  These 
  

   eggs 
  were 
  not 
  hatched, 
  but 
  their 
  resemblance 
  to 
  known 
  eggs 
  of 
  leaf- 
  

   hoppers 
  appears 
  sufficient 
  for 
  their 
  identification. 
  The 
  various 
  species 
  

   hibernate 
  as 
  eggs 
  or 
  as 
  adults, 
  with 
  which 
  larvae 
  are 
  sometimes 
  mingled. 
  

   Those 
  which 
  pass 
  the 
  winter 
  as 
  adults 
  begin 
  to 
  deposit 
  their 
  eggs 
  in 
  

   spring 
  as 
  soon 
  as 
  the 
  season 
  opens, 
  and 
  the 
  young 
  from 
  these 
  and 
  from 
  

   hibernating 
  eggs 
  of 
  the 
  preceding 
  year 
  become 
  abundant 
  in 
  early 
  sum- 
  

   mer. 
  As 
  some 
  species 
  are 
  single-brooded 
  while 
  others 
  of 
  similar 
  habit 
  

   produce 
  two 
  and 
  three 
  or 
  more 
  generations 
  in 
  a 
  year, 
  all 
  stages 
  of 
  these 
  

   insects 
  can 
  be 
  found 
  at 
  almost 
  any 
  time, 
  and 
  systematic 
  discrimination 
  

   of 
  generations 
  can 
  be 
  made 
  by 
  careful 
  breeding 
  experiments 
  only. 
  A 
  

   comparison 
  of 
  dates 
  of 
  collections 
  made 
  by 
  us 
  in 
  Illinois, 
  with 
  those 
  

   made 
  by 
  Professor 
  H. 
  E. 
  Summers 
  in 
  the 
  Southern 
  States 
  goes 
  to 
  show 
  

   that 
  species 
  two-brooded 
  in 
  Illinois 
  are 
  frequently 
  three-brooded 
  farther 
  

   south. 
  

  

  The 
  leaf-hoppers 
  are, 
  on 
  the 
  whole, 
  unusually 
  free 
  from 
  insect 
  

   enemies. 
  Two 
  bugs 
  of 
  predaceous 
  habit 
  feed 
  on 
  them 
  freely, 
  namely, 
  

   the 
  damsel-bug 
  {Coriscus 
  ferns') 
  and 
  the 
  glassy- 
  winged 
  soldier-bug 
  

   {^Hyaliodes 
  vitripennis). 
  Certain 
  parasites 
  also 
  check 
  their 
  multiplica- 
  

   tion 
  by 
  destroying 
  the 
  sexual 
  organs 
  of 
  the 
  adults. 
  

  

  Leaf-hoppers 
  have 
  not 
  thus 
  far 
  been 
  reported 
  as 
  sufificiently 
  injuri- 
  

   ous 
  to 
  the 
  sugar 
  beet 
  to 
  require 
  special 
  measures 
  for 
  their 
  destruction. 
  

   The 
  program 
  of 
  agricultural 
  management 
  included 
  under 
  the 
  general 
  

   head 
  of 
  clean 
  culture 
  — 
  not 
  only 
  for 
  the 
  beet 
  plantation 
  but 
  for 
  the 
  entire 
  

   farm 
  — 
  will 
  tend 
  to 
  keep 
  their 
  numbers 
  down. 
  If, 
  however, 
  they 
  become 
  

   seriously 
  injurious 
  it 
  may 
  profitably 
  be 
  remembered 
  that 
  they 
  may 
  be 
  

   destroyed 
  by 
  the 
  use 
  of 
  kerosene 
  sprays 
  — 
  either 
  the 
  emulsion 
  with 
  soap 
  

  

  