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  435 
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  XVI 
  J. 
  Cocoon 
  Softeninq 
  in 
  some 
  Agrolids 
  (Noctuae). 
  Bv 
  

   T. 
  A. 
  Chapman, 
  M.D.', 
  F.K.S. 
  

  

  [Read 
  November 
  5th, 
  1919.] 
  

   In 
  making 
  some 
  further 
  observations 
  on 
  the 
  resting 
  posi- 
  

   tions 
  of 
  Lepidoptera 
  immediately 
  after 
  the 
  expansion 
  of 
  

   the 
  wings 
  and 
  before 
  the 
  resting 
  attitude 
  normal 
  to 
  the 
  

   species 
  is 
  assumed, 
  I 
  met 
  with 
  a 
  circumstance 
  in 
  con- 
  

   nection 
  Avith 
  the 
  emergence 
  from 
  the 
  pupa 
  of 
  certain 
  Agrotid 
  

   Noctuae 
  that 
  was 
  new 
  to 
  me, 
  and 
  has 
  not 
  so 
  far 
  as 
  I 
  know 
  

   been 
  reported 
  as 
  to 
  that 
  group. 
  The 
  species 
  observed 
  all 
  

   pupate 
  underground, 
  and 
  make 
  a 
  cocoon 
  which 
  usually 
  

   contains 
  a 
  good 
  deal 
  of 
  silk. 
  What 
  I 
  saw 
  seemed 
  unmis- 
  

   takably 
  to 
  indicate 
  that 
  this 
  silk 
  is 
  softened 
  by 
  a 
  special 
  

   secretion 
  by 
  the 
  moth 
  during 
  emergence, 
  so 
  as 
  to 
  facilitate 
  

   its 
  breaking 
  through. 
  

  

  In 
  order 
  to 
  see 
  the 
  moths 
  immediately 
  after 
  the 
  expan- 
  

   sion 
  of 
  the 
  wings, 
  the 
  accident 
  of 
  coming 
  across 
  a 
  moth 
  

   just 
  at 
  that 
  stage, 
  in 
  the 
  breeding 
  cage, 
  is 
  rather 
  uncer- 
  

   tain 
  and 
  very 
  disappointing. 
  It 
  is 
  only 
  too 
  often 
  the 
  case 
  

   that 
  one 
  finds 
  the 
  moth 
  some 
  little 
  time 
  after 
  the 
  critical 
  

   period 
  one 
  wished 
  to 
  see 
  had 
  passed. 
  

  

  To 
  obviate 
  this 
  difficulty 
  I 
  had 
  the 
  pupae 
  out 
  of 
  their 
  

   cocoons 
  and 
  laid 
  them 
  on 
  the 
  bottom 
  of 
  the 
  jar. 
  Like 
  most 
  

   others, 
  these 
  moths 
  emerge 
  at 
  a 
  particular 
  time 
  of 
  day- 
  — 
  ■ 
  

   often, 
  however, 
  spread 
  over 
  several 
  hours. 
  When 
  emer- 
  

   gence 
  is 
  imminent, 
  the 
  pupa, 
  which 
  has 
  been 
  darkening 
  for 
  

   a 
  few 
  days 
  from 
  the 
  brown 
  chitinous 
  colour 
  to 
  nearly 
  black, 
  

   displays 
  the 
  feature 
  that 
  I 
  have 
  called 
  " 
  Inflation." 
  * 
  Air 
  

   is 
  secreted 
  into 
  the 
  ahmentary 
  canal, 
  distending 
  the 
  

   abdomen, 
  so 
  that 
  the 
  segments 
  are 
  stretched 
  apart, 
  exposing 
  

   the 
  intersegmental 
  membrane 
  (between 
  the 
  movable 
  seg- 
  

   ments) 
  and 
  lengthening 
  the 
  abdomen, 
  making 
  a 
  marked 
  

   change 
  in 
  the 
  appearance 
  of 
  the 
  pupa. 
  

  

  When 
  this 
  extension 
  is 
  complete, 
  emergence 
  takes 
  place 
  

   very 
  soon, 
  generally 
  within 
  an 
  hour. 
  By 
  watching 
  for 
  this 
  

   indication, 
  the 
  emergence 
  can 
  be 
  observed, 
  without 
  unduly 
  

   prolonged 
  watching, 
  or 
  futile 
  watching 
  when 
  no 
  emergence 
  

   is 
  due 
  to 
  take 
  place. 
  

  

  Whilst 
  inflation 
  is 
  taking 
  place, 
  the 
  pupa 
  frequently 
  

  

  * 
  Proceedings 
  South 
  London 
  Entomological 
  Society, 
  1902, 
  p. 
  22 
  

   TRANS. 
  ENT. 
  SOC. 
  LOND. 
  1919. 
  — 
  -PARTS 
  III, 
  IV. 
  (dEC.) 
  

  

  