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  PROCEEDINGS 
  OF 
  THE 
  FOURTH 
  ENTOMOLOGICAL 
  MEETING 
  

  

  1919 
  tlie 
  first 
  counts 
  of 
  population 
  of 
  Platyedra 
  were 
  begun 
  and 
  these 
  

   were 
  continued 
  weekly 
  until 
  the 
  following 
  July. 
  At 
  first 
  2,000 
  bolls 
  

   were 
  examined 
  weekly, 
  this 
  then 
  had 
  to 
  be 
  reduced 
  to 
  1,000 
  and 
  finally 
  

   to 
  200. 
  

  

  This 
  was 
  unsatisfactory 
  as, 
  working 
  with 
  small 
  numbers, 
  the 
  error 
  

   is 
  liable 
  to 
  be 
  greater 
  than 
  working 
  with 
  large 
  numbers, 
  but, 
  for 
  causes 
  

   which 
  it 
  would 
  be 
  unprofitable 
  to 
  discuss 
  here, 
  from 
  the 
  middle 
  of 
  March 
  

   to 
  the 
  end 
  of 
  July 
  the 
  supply 
  of 
  bolls 
  had 
  to 
  be 
  limited. 
  

  

  The 
  result 
  of 
  this 
  examination 
  is 
  shown 
  in 
  the 
  accompanying 
  " 
  graph 
  " 
  

   (Plate 
  XIV, 
  fig. 
  1.) 
  

  

  At 
  the 
  beginning 
  of 
  the 
  season 
  the 
  crop 
  was 
  very 
  backward 
  and 
  the 
  

   number 
  of 
  buds 
  and 
  flowers 
  was 
  small 
  ; 
  there 
  was 
  a 
  good 
  deal 
  of 
  boll 
  

   fall 
  also 
  due, 
  as 
  far 
  as 
  could 
  be 
  ascertained, 
  to 
  a 
  small 
  (Capsid). 
  Towards 
  

   the 
  end 
  of 
  January 
  there 
  was 
  a 
  great 
  increase 
  of 
  buds 
  and 
  flowers 
  and 
  the 
  

   percentage 
  population 
  consequently 
  fell 
  rapidly. 
  It 
  rose 
  and 
  fell 
  again 
  

   just 
  after 
  the 
  season-picking 
  and 
  went 
  up 
  with 
  astonishing 
  rapidity 
  

   in 
  the 
  month 
  of 
  July, 
  more 
  especially 
  in 
  the 
  last 
  fortnight. 
  

  

  Arrangements 
  had 
  been 
  made 
  for 
  a 
  weekly 
  supply 
  of 
  bolls 
  from 
  

   various 
  typical 
  tracts 
  of 
  the 
  District, 
  but 
  except 
  in 
  one 
  case 
  this 
  supply 
  

   was 
  not 
  forthcoming 
  after 
  March. 
  So 
  the 
  results 
  obtained 
  from 
  the 
  

   Insectary 
  cotton 
  plots 
  could 
  only 
  be 
  checked 
  with 
  one 
  other 
  place 
  in 
  

   the 
  District, 
  some 
  35 
  miles 
  south 
  of 
  Coimbatore. 
  This 
  curye 
  (the 
  Pol- 
  

   lachi 
  curve) 
  follows 
  the 
  same 
  course 
  as 
  that 
  at 
  Coimbatore, 
  but, 
  as 
  all 
  

   cotton 
  in 
  Pollachi 
  was 
  pulled 
  up 
  early, 
  examinations 
  of 
  bolls 
  up 
  to 
  3rd 
  

   July 
  1920 
  only 
  were 
  possible. 
  (Plate 
  XIV, 
  fig. 
  2.) 
  

  

  Periodically 
  bolls 
  were 
  sent 
  in 
  for 
  examination 
  from 
  districts 
  which 
  

   had 
  not 
  been 
  brought 
  under 
  the 
  rules 
  of 
  the 
  Pest 
  Act. 
  The 
  amount 
  

   of 
  boll-worm 
  attack 
  in 
  these 
  districts 
  varied 
  very 
  much, 
  the 
  highest 
  

   being 
  75 
  per 
  cent, 
  and 
  the 
  lowest 
  45 
  per 
  cent, 
  for 
  the 
  " 
  Kar 
  " 
  or 
  second 
  

   picking. 
  (See 
  tables). 
  

  

  From 
  the 
  end 
  of 
  March 
  up 
  to 
  the 
  end 
  of 
  the 
  season 
  measurements 
  

   were 
  taken 
  of 
  all 
  pink 
  boll-worms 
  found 
  in 
  green 
  bolls, 
  and 
  they 
  were 
  

   then 
  grouped 
  under 
  three 
  heads, 
  those 
  less 
  than 
  5 
  mm., 
  those 
  over 
  5 
  

   mm. 
  but 
  under 
  10 
  and 
  those 
  of 
  ten 
  and 
  over. 
  The 
  percentage 
  of 
  these 
  

   to 
  one 
  another 
  found 
  at 
  any 
  time 
  or 
  over 
  any 
  period 
  should 
  give 
  some 
  idea 
  

   of 
  the 
  appearance 
  of 
  fresh 
  broods 
  and 
  the 
  length 
  of 
  the 
  average 
  life 
  in 
  

   the 
  larval 
  state. 
  (Plate 
  XV, 
  fig. 
  1.) 
  

  

  The 
  curves 
  would 
  seem 
  to 
  indicate 
  that 
  during 
  the 
  hot 
  months 
  of 
  

   the 
  year 
  the 
  larval 
  life 
  is 
  longer 
  than 
  later 
  on. 
  To 
  put 
  it 
  in 
  another 
  way, 
  

   during 
  the 
  time 
  of 
  the 
  season-picking 
  a 
  very 
  high 
  proportion 
  of 
  boll- 
  

   worms 
  found 
  are 
  under 
  10 
  mm., 
  that 
  is 
  to 
  say, 
  they 
  are 
  not 
  in 
  the 
  last 
  

  

  