﻿194 
  BRITISH 
  LEPIDOPTERA. 
  

  

  together 
  on 
  each 
  side 
  of 
  the 
  cocoon. 
  My 
  experience 
  with 
  this 
  brood 
  

   leads 
  me 
  to 
  believe 
  that, 
  when 
  the 
  Senecio 
  stems 
  are 
  of 
  suitable 
  length, 
  

   the 
  larvae, 
  as 
  a 
  rule, 
  pupate 
  therein, 
  but 
  when, 
  owing 
  to 
  any 
  cause, 
  the 
  

   plants 
  are 
  very 
  stunted, 
  the 
  larvae 
  almost, 
  if 
  not 
  quite, 
  invariably 
  

   pupate 
  on 
  the 
  upperside 
  of 
  an 
  upstanding 
  leaf, 
  thereby 
  minimising 
  the 
  

   risk 
  from 
  floods, 
  and 
  securing 
  suitable 
  accommodation, 
  which, 
  owing 
  

   to 
  their 
  own 
  ravages 
  in 
  the 
  stems, 
  probably 
  cannot 
  be 
  found 
  within 
  

   them. 
  After 
  prolonged 
  drought 
  I 
  have 
  found 
  the 
  shoots 
  of 
  Senecio, 
  

   stem 
  and 
  all, 
  not 
  more 
  than 
  an 
  inch 
  or 
  two 
  in 
  height 
  by 
  the 
  end 
  of 
  

   May, 
  when 
  the 
  larvae 
  have 
  mostly 
  pupated, 
  but 
  the 
  radical 
  leaves 
  of 
  the 
  

   foodplant, 
  containing 
  the 
  pupae, 
  were 
  then 
  an 
  inch 
  or 
  two 
  higher, 
  and 
  

   about 
  on 
  a 
  level 
  with 
  the 
  top 
  of 
  the 
  surrounding 
  herbage. 
  The 
  pupae 
  

   of 
  the 
  second 
  brood 
  are 
  found, 
  as 
  a 
  rule, 
  inside 
  the 
  last 
  burrow 
  in 
  

   the 
  main 
  stem 
  of 
  the 
  foodplant." 
  In 
  confinement, 
  pupation 
  of 
  first- 
  

   brood 
  larvae 
  took 
  place 
  in 
  a 
  loose, 
  white, 
  silken 
  web 
  outside 
  the 
  plant, 
  the 
  

   pupa 
  not 
  lying 
  in 
  any 
  particular 
  position. 
  The 
  pupation 
  of 
  the 
  larvae 
  

   of 
  the 
  second 
  brood 
  takes 
  place 
  usually 
  within 
  the 
  stem 
  (Stange). 
  

   Commenting 
  on 
  this 
  difference, 
  Chapman 
  writes 
  (in 
  litt.) 
  : 
  " 
  The 
  sea- 
  

   sonal 
  dimorphism 
  in 
  the 
  matter 
  of 
  the 
  pupating 
  habit 
  is 
  most 
  remark- 
  

   able 
  ; 
  Barrett 
  describes 
  the 
  larva 
  as 
  forming 
  the 
  puparium 
  in 
  the 
  stem 
  

   in 
  which 
  the 
  larva 
  finished 
  feeding, 
  this 
  would 
  be 
  impossible 
  with 
  

   early 
  spring 
  larvae, 
  not 
  merely 
  because 
  there 
  would 
  be 
  danger 
  of 
  their 
  

   being 
  possibly 
  under 
  water, 
  or 
  otherwise 
  badly 
  accommodated, 
  but 
  

   simply 
  because 
  there 
  is 
  no 
  stem 
  for 
  them 
  to 
  pupate 
  in, 
  the 
  largest 
  

   available 
  stem 
  being 
  (comparatively) 
  small, 
  succulent, 
  and 
  rapidly 
  

   growing. 
  The 
  larva 
  therefore 
  leaves 
  the 
  stem 
  (bud, 
  root 
  ?) 
  in 
  which 
  

   it 
  has 
  fed 
  up, 
  and 
  makes 
  a 
  definite 
  cocoon 
  elsewhere. 
  Mr. 
  Bankes 
  sends 
  

   four 
  such 
  cocoons 
  on 
  leaves 
  of 
  the 
  Senecio, 
  and 
  larvae 
  in 
  captivity 
  have 
  

   made 
  similar 
  cocoons 
  on 
  leaves, 
  and 
  have 
  nibbled 
  and 
  torn 
  paper 
  to 
  

   make 
  it 
  suit 
  their 
  requirements. 
  They 
  fold 
  over 
  a 
  leaf 
  till 
  it 
  nearly 
  

   meets 
  (and 
  serve 
  paper 
  in 
  the 
  same 
  way), 
  and 
  across 
  the 
  small 
  remain- 
  

   ing 
  gap 
  is 
  spun 
  a 
  strong 
  opaque 
  diaphragm 
  of 
  silk 
  for 
  part 
  of 
  the 
  fold, 
  

   and, 
  at 
  the 
  top, 
  the 
  silk 
  spreads 
  out 
  more 
  thinly 
  into 
  a 
  short 
  funnel-like 
  

   portion, 
  through 
  which 
  the 
  anterior 
  end 
  of 
  the 
  pupa 
  can 
  be 
  seen 
  as 
  

   through 
  a 
  very 
  slight 
  screen, 
  and 
  through 
  which 
  the 
  moth 
  is 
  to 
  emerge. 
  

   The 
  silk 
  is 
  whity-brown 
  in 
  colour, 
  and 
  seems 
  to 
  have 
  some 
  particles 
  

   entangled 
  in 
  it 
  in 
  some 
  cases." 
  Bacot 
  writes 
  (August 
  12th, 
  1904) 
  : 
  

   " 
  I 
  am 
  rather 
  puzzled 
  as 
  to 
  where 
  pupation 
  is 
  taking 
  place 
  ; 
  I 
  found 
  

   one 
  pupa 
  spun-up 
  on 
  the 
  upperside 
  of 
  a 
  leaf, 
  but 
  can 
  find 
  no 
  more 
  

   pupae 
  externally 
  on 
  the 
  plant. 
  Two 
  others 
  I 
  found 
  on 
  the 
  earth 
  as 
  

   though 
  they 
  had 
  fallen, 
  and 
  I 
  suspect 
  the 
  larvae 
  have 
  pupated 
  within 
  

   the 
  plant, 
  and 
  that 
  they 
  wriggle 
  out 
  of 
  their 
  puparia 
  occasionally 
  as 
  in 
  

   the 
  two 
  individuals 
  just 
  noted." 
  

  

  Pupa. 
  — 
  The 
  pupa 
  is, 
  in 
  some 
  specimens 
  I 
  have, 
  pale 
  terra-cotta, 
  

   with 
  practically 
  no 
  dark 
  markings 
  ; 
  some 
  of 
  the 
  summer 
  pupae 
  are 
  

   well-marked, 
  but 
  none 
  anywhere 
  approaching 
  black, 
  which 
  is, 
  I 
  

   imagine, 
  rather 
  a 
  rare 
  form, 
  as 
  it 
  does 
  not 
  occur 
  amongst 
  a 
  number 
  of 
  

   (spring 
  ?) 
  pupae 
  sent 
  me 
  by 
  Mr. 
  Bankes. 
  Of 
  these, 
  some 
  are 
  very 
  dark 
  

   and 
  some 
  very 
  light-coloured. 
  All 
  these 
  Platyptiliine 
  pupae 
  are 
  very 
  

   much 
  alike, 
  but 
  that 
  of 
  P. 
  isodactylus 
  is 
  at 
  once 
  distinguished 
  from 
  all 
  

   the 
  others 
  by 
  the 
  ridge, 
  carrying 
  spines, 
  which 
  encircles 
  the 
  abdominal 
  

   segments, 
  just 
  above 
  the 
  line 
  separating 
  the 
  front 
  part 
  of 
  the 
  segment 
  

   from 
  the 
  intersegmental 
  subsegment 
  ; 
  it 
  is 
  present 
  on 
  the 
  3rd, 
  4th, 
  5th, 
  

  

  