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  PEOCEEDINGS 
  OF 
  THE 
  FOURTH 
  ENTOMOLOGICAL 
  MEETING 
  

  

  up 
  to 
  February 
  and 
  March 
  but 
  with 
  the 
  rising 
  temperature 
  and 
  gradually 
  

   decreasing 
  humidity 
  their 
  functional 
  activity, 
  which 
  reaches 
  its 
  maximum 
  

   in 
  February 
  and 
  March, 
  is 
  reversed 
  and 
  the 
  grubs 
  after 
  spinning 
  the 
  

   cocoons 
  go 
  into 
  aestivation. 
  The 
  aestivating 
  cocoons 
  lie 
  scattered 
  all 
  

   over 
  the 
  attacked 
  area 
  in 
  large 
  numbers 
  but 
  the 
  majority 
  of 
  them 
  are 
  

   killed 
  ofi 
  by 
  the 
  adverse 
  conditions 
  obtaining 
  in 
  the 
  chaur 
  lands, 
  viz., 
  

   extremely 
  dry 
  hot 
  winds 
  in 
  April 
  and 
  May 
  but 
  submergence 
  under 
  flood 
  

   water 
  for 
  about 
  tw^o 
  months 
  in 
  the 
  rains. 
  It 
  is 
  only 
  those 
  few 
  

   formed 
  in 
  favourable 
  situations 
  which 
  survive 
  through 
  summer 
  and 
  the 
  

   rains. 
  The 
  favourable 
  spots 
  are 
  the 
  deep 
  cracks 
  in 
  the 
  soil, 
  with 
  which 
  

   the 
  whole 
  surface 
  is 
  interspersed, 
  way 
  up 
  on 
  the 
  comparatively 
  higher 
  

   land 
  bordering 
  the 
  flooded 
  areas 
  and 
  beyond 
  the 
  flood 
  water 
  level. 
  The 
  

   moisture 
  content 
  of 
  soil 
  in 
  such 
  cracks 
  at 
  different 
  depths 
  was 
  determined 
  

   in 
  May 
  1919 
  and 
  was 
  found 
  to 
  be 
  9-5 
  per 
  cent, 
  at 
  a 
  depth 
  of 
  6 
  inches, 
  

   16-6 
  per 
  cent, 
  at 
  12 
  inches 
  and 
  21-0 
  per 
  cent, 
  at 
  18 
  inches. 
  Samples 
  of 
  

   soils 
  were 
  collected 
  on 
  a 
  day 
  when 
  the 
  temperature 
  in 
  shade 
  was 
  108°F. 
  

   relative 
  humidity 
  of 
  the 
  atmosphere 
  varied 
  from 
  10 
  to 
  20 
  at 
  midday 
  and 
  

   there 
  had 
  been 
  no 
  rain 
  during 
  the 
  previous 
  15 
  days. 
  As 
  regards 
  

   temperature 
  it 
  should 
  be 
  quite 
  favourable 
  at 
  such 
  depth 
  as 
  in 
  high 
  

   lands 
  the 
  difference 
  between 
  the 
  temperature 
  of 
  soil 
  at 
  the 
  first 
  inch 
  and 
  

   at 
  a 
  depth 
  of 
  18 
  inches 
  is 
  about 
  18°F. 
  in 
  May. 
  The 
  conditions 
  at 
  the 
  

   bottom 
  of 
  the 
  cracks 
  are 
  therefore 
  favourable 
  enough 
  for 
  keeping 
  the 
  

   cocoons 
  alive 
  but 
  not 
  for 
  the 
  development 
  of 
  the 
  grubs 
  within 
  or 
  for 
  the 
  

   emergence 
  of 
  the 
  adults 
  which 
  require 
  a 
  much 
  lower 
  temperature. 
  When 
  

   therefore 
  the 
  caterpillar 
  pest 
  first 
  appears 
  in 
  the 
  field 
  under 
  normal 
  

   conditions 
  in 
  September 
  or 
  October 
  the 
  number 
  of 
  surviving 
  parasites 
  

   is 
  far 
  too 
  low 
  to 
  be 
  of 
  any 
  effective 
  use 
  in 
  controlling 
  the 
  first 
  brood. 
  

   With 
  the 
  appearance 
  of 
  the 
  host 
  insect 
  however, 
  they 
  continue 
  to 
  have 
  

   brood 
  after 
  brood 
  until 
  their 
  number 
  is 
  sufficiently 
  large 
  in 
  December 
  to 
  

   enable 
  them 
  to 
  parasitize 
  70 
  per 
  cent, 
  of 
  the 
  enormously 
  large 
  destructive 
  

   second 
  brood 
  of 
  the 
  caterpillar 
  pest. 
  

  

  ///. 
  Reactions 
  to 
  Temperature 
  and 
  Humidity. 
  

  

  With 
  a 
  view 
  to 
  utilizing 
  the 
  parasite 
  as 
  a 
  means 
  of 
  controlling 
  the 
  

   caterpillar 
  pest, 
  its 
  reactions 
  to 
  temperature 
  and 
  humidity 
  are 
  being 
  

   studied 
  in 
  the 
  Insectary 
  at 
  Sabour 
  for 
  the 
  last 
  two 
  years. 
  The 
  object 
  of 
  

   the 
  work 
  has 
  been 
  to 
  determine 
  the 
  factors 
  controlling 
  its 
  aestivation 
  and 
  

   emergence 
  definitely 
  so 
  as 
  to 
  be 
  able 
  to 
  have 
  in 
  hand 
  enough 
  parasites, 
  

   readily 
  emerged, 
  in 
  September 
  or 
  October 
  for 
  liberation 
  in 
  the 
  affected 
  

   areas 
  just 
  when 
  the 
  first 
  brood 
  of 
  the 
  caterpillar 
  pest 
  is 
  noticed 
  there. 
  

   Under 
  ordinary 
  conditions 
  it 
  is 
  not 
  possible 
  to 
  have 
  a 
  large 
  number 
  of 
  

   adult 
  parasites 
  at 
  that 
  time 
  as 
  they 
  cannot 
  be 
  reared 
  through 
  the 
  summer 
  

  

  