﻿PROCEEDINGS 
  OF 
  THE 
  FOURTH 
  ENTOMOLOGICAL 
  MEETING 
  73 
  

  

  Short 
  and 
  Long 
  Cycle 
  Larvce. 
  — 
  Apart 
  from 
  the 
  actual 
  damage 
  it 
  does 
  

   rto 
  the 
  seeds 
  of 
  the 
  lint, 
  P. 
  gossypiella 
  possesses 
  another 
  habit 
  which 
  

   helps 
  to 
  make 
  it 
  a 
  danger 
  to 
  cotton 
  growers 
  and 
  has 
  been 
  largely 
  responsi- 
  

   ble 
  for 
  its 
  world-wide 
  distribution. 
  This 
  habit 
  is 
  that 
  at 
  certain 
  seasons 
  

   of 
  the 
  year 
  it 
  produces 
  two 
  kinds 
  of 
  larvee, 
  known 
  generally 
  as 
  short- 
  

   cycle 
  larvae 
  and 
  long-cycle 
  larv«. 
  These 
  larvae 
  either 
  complete 
  their 
  

   lifehistory 
  in 
  three 
  weeks 
  or 
  a 
  month 
  from 
  the 
  time 
  of 
  hatching 
  or 
  remain 
  

   in 
  the 
  larval 
  state 
  for 
  any 
  time 
  up 
  to 
  two 
  years. 
  Lefroy 
  (*) 
  states 
  that 
  

   in 
  Northern 
  India 
  there 
  are 
  two 
  such 
  periods 
  in 
  the 
  year, 
  when 
  long- 
  

   cycle 
  larvae 
  are 
  produced, 
  but 
  generally 
  it 
  is 
  only 
  at 
  one 
  time. 
  In 
  Egypt 
  

   this 
  is 
  towards 
  the 
  end 
  of 
  the 
  year. 
  This 
  resting 
  stage 
  is 
  passed 
  in 
  the 
  

   seed, 
  generally 
  inside 
  double 
  seeds, 
  that 
  is 
  to 
  say, 
  two 
  seeds 
  bound 
  

   together 
  by 
  the 
  larva 
  with 
  sUk. 
  It 
  is 
  unnecessary 
  to 
  emphasize 
  how 
  

   dangerous 
  is 
  this 
  capacity 
  for 
  prolonging 
  the 
  larval 
  life 
  and 
  how 
  easily 
  

   this 
  may 
  be 
  the 
  cause 
  of 
  infection 
  of 
  the 
  growing 
  crop. 
  It 
  helps 
  the 
  

   insects 
  to 
  defy 
  the 
  laws 
  which 
  decree 
  a 
  dead 
  period 
  between 
  the 
  pulling 
  

   up 
  of 
  one 
  crop 
  and 
  the 
  sowing 
  of 
  another 
  in 
  the 
  hope 
  of 
  starving 
  the 
  

   pest 
  out 
  of 
  existence. 
  For 
  this 
  reason, 
  in 
  Egypt 
  ail 
  seed 
  has 
  to 
  be 
  treated 
  

   as 
  soon 
  as 
  it 
  is 
  ginned 
  and 
  precautions 
  have 
  to 
  be 
  taken 
  to 
  screen 
  seed 
  

   and 
  kappas 
  stores, 
  as 
  they 
  would 
  otherwise 
  be 
  easily 
  the 
  cause 
  of 
  infection 
  

   of 
  the 
  growing 
  crop(^). 
  

  

  Our 
  investigations 
  for 
  1919-20 
  go 
  to 
  show 
  that 
  it 
  is 
  extremely 
  doubt- 
  

   ful 
  whether 
  this 
  resting 
  or 
  long 
  cycle 
  type 
  of 
  larva 
  is 
  produced 
  in 
  South 
  

   India. 
  What 
  the 
  factors 
  are 
  which 
  induce 
  this 
  resting 
  stage 
  or 
  pro- 
  

   hibit 
  it 
  are 
  unknown. 
  It 
  may 
  be 
  that 
  the 
  absence 
  of 
  any 
  cold 
  weather 
  

   in 
  South 
  India 
  inhibits 
  any 
  tendency 
  for 
  P. 
  gossypiella 
  to 
  produce 
  long- 
  

   cycle 
  larvae 
  but, 
  whatever 
  the 
  cause, 
  as 
  far 
  as 
  we 
  can 
  tell 
  at 
  present 
  they 
  

   are 
  never 
  or 
  only 
  very 
  rarely 
  produced. 
  Double 
  seeds 
  have 
  been 
  found 
  

   but 
  either 
  without 
  a 
  larva 
  inside 
  or 
  containing 
  a 
  pupa. 
  Large 
  quantities 
  

   of 
  infested 
  seed, 
  kappas 
  and 
  bolls 
  have 
  been 
  kept 
  at 
  the 
  Insectary 
  and 
  

   examination 
  has 
  been 
  made 
  of 
  seed 
  stores 
  but 
  in 
  practically 
  every 
  case 
  

   no 
  moths 
  emerged 
  more 
  than 
  a 
  month 
  after 
  ginning 
  or 
  picking. 
  Three 
  

   cases 
  are 
  recorded, 
  two 
  from 
  a 
  seed 
  store 
  in 
  which 
  two 
  moths 
  emerged 
  

   early 
  in 
  November 
  from 
  seed 
  ginned 
  in 
  May 
  or 
  June. 
  One 
  larva 
  was 
  

   found 
  in 
  a 
  cocoon 
  made 
  in 
  kappas 
  picked 
  three 
  or 
  four 
  months 
  previously. 
  

   The 
  exact 
  date 
  of 
  ginning 
  and 
  picking 
  was 
  not 
  available 
  in 
  each 
  case. 
  

  

  Damage. 
  — 
  The 
  damage 
  done 
  by 
  the 
  pink 
  boll- 
  worm 
  is 
  difficult 
  to 
  

   estimate 
  in 
  terms 
  of 
  money. 
  So 
  many 
  different 
  factors 
  are 
  involved 
  

   and 
  what 
  might 
  apply 
  to 
  one 
  field 
  might 
  not 
  apply 
  to 
  another. 
  The 
  

   damage 
  is 
  done 
  in 
  four 
  or 
  five 
  ways. 
  

  

  (1) 
  By 
  the 
  seed 
  being 
  destroyed. 
  

  

  (2) 
  By 
  the 
  development 
  of 
  the 
  lint 
  being 
  retarded 
  and 
  lint 
  weakened. 
  

  

  