﻿PLA.TYPTILIA 
  ISODACTYLUS. 
  189 
  

  

  25th, 
  1905, 
  some 
  dead 
  plants 
  were 
  examined, 
  and 
  two, 
  small, 
  cocoon- 
  

   like 
  cavities 
  were 
  found 
  in 
  the 
  bases 
  of 
  the 
  leaves, 
  i.e., 
  the 
  petiole 
  

   close 
  to 
  the 
  centre, 
  but 
  the 
  larvae 
  had 
  gone 
  ; 
  there 
  was 
  a 
  little 
  silk, 
  and 
  the 
  

   cavities 
  were 
  apparently 
  between 
  two 
  leaves, 
  though 
  their 
  actual 
  hollows 
  

   were 
  excavated 
  out 
  of 
  one 
  of 
  them 
  (Chapman). 
  Larvae 
  found 
  on 
  May 
  19th, 
  

   1904, 
  in 
  the 
  Wareham 
  district, 
  after 
  hybernation, 
  varied 
  much 
  in 
  size, 
  

   some 
  being 
  quite 
  fullfed. 
  Two 
  of 
  the 
  tenanted 
  plants 
  of 
  S. 
  aquaticm 
  

   contained 
  two 
  larvae, 
  feeding 
  in 
  the 
  same 
  stem 
  ; 
  owing 
  to 
  the 
  luxuri- 
  

   ance 
  of 
  the 
  vegetation 
  the 
  larvae 
  seemed 
  specially 
  hard 
  to 
  find 
  (Bankes). 
  

   The 
  larvae 
  found 
  (by 
  Bankes) 
  were 
  forwarded 
  to 
  Chapman 
  on 
  May 
  

   21st, 
  who 
  reports 
  : 
  The 
  larvae 
  have 
  the 
  appearance 
  of 
  being 
  fat 
  white 
  

   grubs, 
  of 
  the 
  same 
  outline 
  and 
  build 
  as 
  gonodactyla, 
  ochrodactyla, 
  etc., 
  

   but 
  rather 
  stouter 
  and 
  longer, 
  10mm. 
  x2-6mm. 
  or 
  12mm. 
  x2-3mm., 
  

   according 
  as 
  to 
  whether 
  one 
  is 
  stretched 
  or 
  retracted. 
  The 
  larva 
  is 
  a 
  

   typical 
  internal 
  feeder 
  by 
  aspect, 
  white 
  (really 
  faint 
  greenish-yellow), 
  

   with 
  black 
  head, 
  prothoracic 
  plate, 
  spiracles, 
  and 
  tubercles 
  to 
  anal 
  

   plate. 
  On 
  closer 
  examination, 
  the 
  whiter 
  patches 
  round 
  the 
  tubercles, 
  

   making 
  subdorsal 
  (including 
  i 
  and 
  ii) 
  and 
  supraspiracular 
  (including 
  

   hi). 
  bands, 
  and 
  a 
  subspiracular 
  (including 
  iv 
  and 
  v) 
  flange, 
  are 
  readily 
  

   distinguished. 
  Numerous 
  minute 
  black 
  secondary 
  hairs 
  are 
  also 
  seen, 
  

   darkest 
  and 
  most 
  evident, 
  dorsally 
  and 
  sublaterally. 
  The 
  larva& 
  

   excavate 
  the 
  central 
  bud 
  of 
  the 
  Senecio, 
  clearing 
  it 
  out 
  completely, 
  and 
  

   making 
  their 
  wide 
  cavity 
  down 
  quite 
  (or 
  just) 
  into 
  the 
  root, 
  if 
  by 
  root 
  

   we 
  understand 
  all 
  below 
  the 
  level 
  at 
  which 
  root-fibres 
  are 
  given 
  off. 
  

   Comparing 
  the 
  material 
  before 
  me 
  with 
  Buckler's 
  and 
  Barrett's 
  

   account 
  of 
  the 
  larva 
  and 
  its 
  habits, 
  one 
  notes 
  that 
  they 
  describe 
  the 
  

   second 
  brood, 
  this 
  is 
  the 
  first, 
  and, 
  moreover, 
  these 
  (on 
  May 
  20th) 
  are 
  

   fullfed. 
  The 
  plants 
  are 
  at 
  most 
  a 
  few 
  inches 
  high, 
  and 
  those 
  in 
  which 
  

   the 
  larvae 
  are, 
  are 
  less 
  than 
  an 
  inch, 
  growth 
  being 
  checked 
  by 
  the 
  

   larval 
  attack. 
  The 
  roots 
  are, 
  however, 
  thick 
  and 
  strong, 
  doubtless 
  

   being 
  the 
  stored-up 
  material 
  which 
  carries 
  the 
  plant 
  through 
  the 
  

   winter 
  and 
  starts 
  it 
  in 
  spring. 
  There 
  is 
  no 
  evidence 
  of 
  how 
  the 
  larva 
  

   passes 
  the 
  winter, 
  but 
  it 
  probably 
  does 
  so 
  on 
  (or 
  in 
  ?) 
  the 
  shoot 
  it 
  now 
  

   inhabits. 
  The 
  larvae 
  being 
  fullgrown, 
  and 
  nearly 
  all 
  eating 
  the 
  white 
  

   pith 
  or 
  heart 
  of 
  the 
  young 
  shoot, 
  they 
  quite 
  lack 
  the 
  greenish 
  tint 
  

   Buckler 
  describes. 
  The 
  skin 
  is 
  absolutely 
  without 
  colour, 
  thin 
  and 
  

   pellucid 
  in 
  places, 
  thicker 
  and 
  whiter 
  in 
  others. 
  These 
  white 
  patches- 
  

   surround 
  the 
  tubercles, 
  and 
  nearly 
  run 
  together 
  into 
  similar 
  white 
  

   stripes 
  as 
  those 
  that 
  occur 
  in 
  Gillmeriapallidactyla 
  (bertratni), 
  etc., 
  and 
  

   are 
  the 
  white 
  areas 
  described 
  by 
  Buckler. 
  The 
  more 
  delicate 
  portions 
  are 
  

   coloured 
  according 
  to 
  the 
  material 
  beneath. 
  In 
  my 
  specimens, 
  the 
  

   fluid 
  (blood) 
  is 
  practically 
  colourless, 
  the 
  fat-bodies 
  are 
  abundant 
  and 
  

   white, 
  and 
  the 
  contents 
  of 
  the 
  alimentary 
  canal 
  are 
  white 
  forwards 
  

   and 
  dirty 
  dingy 
  posteriorly. 
  The 
  total 
  result 
  is, 
  however, 
  that 
  we 
  

   have 
  a 
  white 
  larva, 
  in 
  which 
  the 
  differentiation 
  of 
  the 
  skin 
  into 
  white 
  

   and 
  colourless 
  areas 
  is 
  not 
  at 
  all 
  conspicuous. 
  Buckler's 
  Larvae 
  were 
  

   not 
  all 
  fullfed, 
  and, 
  moreover, 
  they 
  fed 
  on 
  green 
  food. 
  /'.<•., 
  the 
  leaves, 
  

   buds 
  and 
  stems, 
  well 
  above 
  the 
  ground, 
  mine 
  are 
  feeding 
  m 
  the 
  stem 
  at. 
  or 
  

   below, 
  ground 
  level 
  (Chapman). 
  Bankes 
  writes 
  [in 
  litt.) 
  : 
  " 
  The 
  larva 
  1 
  o< 
  

   both 
  broods 
  feed 
  throughout 
  inside, 
  and 
  on 
  the 
  pith 
  o(, 
  the 
  stems 
  ol 
  

   Senecio 
  (ttjttaticus 
  (although, 
  when 
  those 
  of 
  the 
  earlier 
  ones 
  are 
  feeding, 
  

   these 
  stems 
  are 
  often 
  very 
  short) 
  , 
  entering 
  the 
  first 
  stem 
  at 
  us 
  terminal 
  

   bud 
  and 
  burrowing 
  downwards; 
  later 
  on, 
  they 
  readily 
  come 
  out 
  as 
  often 
  

  

  