﻿81 
  

  

  the 
  surface 
  of 
  water 
  from 
  seven 
  to 
  fifteen 
  days, 
  with 
  an 
  average 
  of 
  

   about 
  thirteen. 
  To 
  determine 
  whether 
  the 
  hibernating 
  generation 
  

   might 
  be 
  more 
  readily 
  aflPected 
  by 
  moisture 
  after 
  prolonged 
  exj)osure 
  

   to 
  the 
  winter, 
  a 
  similar 
  experiment 
  was 
  tried, 
  beginning 
  March 
  31, 
  

   1896. 
  with 
  small 
  lots 
  of 
  chinch-bugs 
  carefully 
  placed 
  upon 
  the 
  sur- 
  

   face 
  of 
  water 
  in 
  glasses 
  and 
  covered 
  with 
  fine 
  Swiss 
  muslin. 
  These 
  

   hibernating 
  adults, 
  brought 
  in 
  from 
  the 
  field 
  at 
  the 
  time, 
  lived 
  from 
  

   three 
  to 
  twenty-one 
  days, 
  being 
  an 
  average 
  of 
  a 
  little 
  over 
  twelve 
  

   days 
  — 
  a 
  result 
  so 
  similar 
  to 
  that 
  of 
  the 
  preceding 
  year 
  that 
  it 
  seems 
  

   likely 
  that 
  there 
  is 
  little 
  difference 
  between 
  the 
  capacity 
  of 
  the 
  two 
  

   generations 
  of 
  this 
  insect 
  to 
  withstand 
  the 
  effect 
  of 
  continued 
  moist- 
  

   ure. 
  On 
  the 
  other 
  hand, 
  an 
  equal 
  number 
  of 
  specimens, 
  similarly 
  

   placed 
  except 
  that 
  the 
  dishes 
  containing 
  them 
  were 
  covered 
  with 
  

   glass 
  plates 
  so 
  as 
  to 
  keep 
  the 
  atmosphere 
  thoroughly 
  saturated 
  

   throughout, 
  lived 
  on 
  an 
  average 
  only 
  eight 
  and 
  two-third 
  days. 
  

  

  10. 
  Confinement 
  of 
  Hibernatincj 
  Chinch-bngs. 
  — 
  The 
  vitality 
  of 
  

   this 
  generation 
  was 
  still 
  further 
  tested 
  by 
  putting 
  eighteen 
  speci- 
  

   mens 
  in 
  three 
  lots 
  of 
  six 
  each 
  in 
  covered 
  glass 
  dishes 
  over 
  moist 
  

   earth, 
  this 
  being 
  occasionally 
  moistened 
  to 
  maintain 
  normal 
  con- 
  

   ditions. 
  In 
  this 
  experiment, 
  begun 
  March 
  .Bl, 
  the 
  chinch-bugs, 
  kept 
  

   without 
  food, 
  began 
  to 
  die 
  April 
  25 
  and 
  were 
  all 
  dead 
  on 
  the 
  18th 
  of 
  

   May, 
  the 
  average 
  length 
  of 
  life 
  under 
  these 
  circumstances 
  being 
  

   thirty-eight 
  days. 
  In 
  a 
  similar 
  experiment, 
  begun 
  at 
  the 
  same 
  time, 
  

   with 
  an 
  equal 
  number 
  of 
  insects, 
  kept 
  under 
  like 
  conditions 
  except 
  that 
  

   the 
  glass 
  vessels 
  were 
  covered 
  with 
  Swiss 
  muslin 
  and 
  that 
  no 
  water 
  

   was 
  supplied, 
  the 
  bugs 
  began 
  to 
  die 
  in 
  four 
  days 
  and 
  were 
  all 
  dead 
  

   in 
  eight, 
  the 
  average 
  being 
  between 
  five 
  and 
  six 
  days. 
  Where 
  the 
  

   glass 
  was 
  empty, 
  the 
  conditions 
  being 
  otherwise 
  the 
  same, 
  deaths 
  

   began 
  in 
  two 
  days 
  and 
  all 
  the 
  bugs 
  were 
  dead 
  in 
  four, 
  the 
  average 
  

   period 
  of 
  survival 
  being 
  between 
  two 
  and 
  three 
  days. 
  In 
  these 
  last 
  

   two 
  experiments 
  death 
  was 
  evidently 
  caused 
  by 
  drouth, 
  and 
  in 
  the 
  

   first 
  one 
  by 
  starvation. 
  

  

  These 
  results 
  are 
  fairly 
  similar 
  to 
  those 
  of 
  like 
  experiments 
  with 
  

   the 
  midsummer 
  generation 
  reported 
  on 
  pages 
  187 
  and 
  188 
  of 
  my 
  

   previous 
  report, 
  and 
  afford 
  additional 
  evidence 
  that 
  the 
  hibernating 
  

   generation 
  is 
  not 
  noticeably 
  weakened 
  by 
  its 
  exposure 
  to 
  winter 
  

   conditions. 
  

  

  A 
  comparison 
  of 
  these 
  results 
  with 
  those 
  reported 
  under 
  experi- 
  

   ment 
  No. 
  6, 
  on 
  page 
  185 
  of 
  my 
  Eighth 
  Report, 
  would 
  seem 
  to 
  indicate 
  

   about 
  an 
  equal 
  power 
  of 
  resistance 
  to 
  continuous 
  submersion 
  on 
  the 
  

   part 
  of 
  chinch-bugs 
  of 
  this 
  hibernating 
  generation 
  collected 
  in 
  fall 
  

   and 
  those 
  collected 
  in 
  spring. 
  Experiment 
  No. 
  5, 
  on 
  the 
  other 
  hand, 
  

   described 
  on 
  page 
  184, 
  shows 
  that 
  the 
  freshly 
  molted 
  adults 
  are 
  more 
  

   delicate 
  than 
  hardened 
  adults. 
  

  

  Immersion 
  of 
  Hibernating 
  Chinch-bugs. 
  — 
  From 
  a 
  series 
  of 
  

   twenty-one 
  experiments 
  made 
  to 
  determine 
  the 
  capacity 
  of 
  the 
  hiber- 
  

   nating 
  generation 
  to 
  sustain 
  continuous 
  immersion 
  in 
  water, 
  we 
  

   learn 
  that 
  complete 
  submersion 
  in 
  rain 
  water 
  at 
  a 
  temperature 
  of 
  70° 
  

   Fah. 
  was 
  sustained 
  without 
  loss 
  of 
  life 
  for 
  periods 
  varying 
  from 
  

   (\ 
  

  

  