﻿45 
  

  

  A 
  STUDY 
  OF 
  THE 
  CAUSES 
  OF 
  THE 
  DISAPPEARANCE 
  

   OF 
  A 
  CHINCH-BUG 
  OUTBREAK. 
  

  

  One 
  of 
  the 
  most 
  strongly 
  marked 
  and 
  important 
  features 
  of 
  the 
  

   economy 
  of 
  the 
  chinch-bug 
  is 
  the 
  enormous 
  variation 
  in 
  its 
  numbers 
  

   in 
  any 
  given 
  locality 
  from 
  year 
  to 
  year. 
  Increasing 
  in 
  a 
  maximum 
  

   ratio 
  of 
  over 
  one 
  hundred 
  per 
  cent, 
  in 
  each 
  of 
  its 
  two 
  annual 
  gener- 
  

   ations, 
  its 
  injuries 
  may 
  rise 
  in 
  three 
  or 
  four 
  years, 
  under 
  favorable 
  

   conditions, 
  from 
  utter 
  insignificance 
  to 
  the 
  proportions 
  of 
  an 
  agricul- 
  

   tural 
  calamity. 
  Such 
  outbreaks 
  commonly 
  disappear^ 
  however, 
  more 
  

   rapidly 
  than 
  they 
  develop, 
  the 
  wave 
  of 
  increase 
  sometimes 
  receding, 
  

   as 
  in 
  Southern 
  Illinois 
  in 
  1887, 
  from 
  its 
  highest 
  to 
  its 
  lowest 
  level 
  in 
  

   a 
  single 
  year. 
  The 
  causes 
  of 
  this 
  rapid 
  decline 
  in 
  the 
  numbers 
  of 
  a 
  

   destructive 
  chinch-bug 
  horde 
  are 
  too 
  little 
  known 
  as 
  yet 
  to 
  permit 
  

   us 
  to 
  recognize 
  them 
  with 
  certainty 
  when 
  they 
  appear, 
  and 
  this 
  ir- 
  

   regular 
  variation 
  in 
  numbers 
  makes 
  the 
  farmer 
  uncertain 
  what 
  to 
  

   expect 
  from 
  the 
  chinch-bug 
  in 
  any 
  year, 
  thus, 
  preventing, 
  as 
  a 
  rule, 
  

   all 
  intelligent 
  adjustment 
  of 
  plans 
  and 
  methods 
  to 
  the 
  probabilities 
  

   of 
  the 
  season. 
  If 
  the 
  damage 
  done 
  bj^ 
  this 
  insect 
  were 
  equally 
  dis- 
  

   tributed 
  in 
  time, 
  or 
  if 
  its 
  periods 
  of 
  increase 
  and 
  decrease 
  had 
  any 
  

   calculable 
  regularity, 
  or 
  if 
  either 
  the 
  rise 
  or 
  fall 
  of 
  the 
  wave 
  were 
  

   commonly 
  preceded 
  by 
  any 
  recognizable 
  sign 
  of 
  the 
  event, 
  preven- 
  

   tive 
  measures 
  might 
  be 
  very 
  generally 
  taken; 
  but, 
  as 
  it 
  is, 
  the 
  average 
  

   farmer 
  in 
  the 
  region 
  most 
  liable 
  to 
  attack 
  prefers 
  to 
  speculate 
  on 
  the 
  

   uncertainties 
  of 
  the 
  future, 
  taking 
  his 
  chances 
  year 
  after 
  year 
  with 
  

   about 
  the 
  same 
  procedure 
  which 
  he 
  would 
  use 
  if 
  there 
  were 
  no 
  

   chinch-bugs 
  in 
  existence. 
  The 
  final 
  loss 
  thus 
  falls 
  upon 
  him 
  and 
  

   upon 
  the 
  agriculture 
  of 
  the 
  State 
  almost 
  without 
  mitigation, 
  for 
  

   remedies 
  effective 
  after 
  an 
  attack 
  has 
  begun 
  are 
  very 
  few 
  and 
  but 
  

   little 
  used. 
  It 
  is 
  a 
  matter 
  of 
  considerable 
  consequence, 
  therefore, 
  

   that 
  the 
  causes 
  of 
  the 
  recession 
  of 
  this 
  wave-like 
  movement 
  of 
  chinch- 
  

   bug 
  reproduction 
  be 
  thoroughly 
  investigated, 
  at 
  least 
  so 
  long 
  as 
  

   there 
  is 
  any 
  hope 
  remaining 
  that 
  a 
  full 
  knowledge 
  of 
  them 
  would 
  

   enable 
  us 
  to 
  foresee 
  with 
  some 
  definiteness 
  the 
  probabilities 
  of 
  the 
  

   season 
  or 
  of 
  the 
  coming 
  year. 
  So 
  long, 
  furthermore, 
  as 
  we 
  can 
  be- 
  

   lieve 
  that 
  there 
  is 
  the 
  least 
  chance 
  that 
  any 
  of 
  the 
  natural 
  checks 
  

   upon 
  the 
  increase 
  of 
  this 
  insect 
  may 
  be 
  brought 
  under 
  our 
  control, 
  

   and 
  used 
  at 
  will 
  for 
  the 
  reduction 
  of 
  a 
  destructive 
  outbreak, 
  or 
  for 
  

   the 
  local 
  defense 
  of 
  endangered 
  crojjs, 
  we 
  are 
  not 
  at 
  liberty 
  to 
  aban- 
  

   don 
  investigation 
  as 
  hopeless, 
  or 
  to 
  remit 
  in 
  the 
  least 
  our 
  efforts 
  to 
  

   learn 
  the 
  full 
  and 
  precise 
  truth. 
  

  

  