﻿218 
  

  

  R. 
  J. 
  TILLYARD. 
  

  

  text-fig. 
  8, 
  while 
  those 
  on 
  the 
  remaining 
  segments 
  are 
  very 
  minute 
  and 
  abundant. 
  

   The 
  most 
  striking 
  change 
  is 
  in 
  the 
  size 
  and 
  shape 
  of 
  the 
  spiracles. 
  The 
  prothoracic 
  

   spiracle 
  is 
  now 
  twice 
  as 
  long 
  as 
  in 
  the 
  previous 
  instar, 
  measuring 
  0-32 
  mm. 
  in 
  length 
  ; 
  

   its 
  breadth 
  is 
  only 
  one-fourth 
  of 
  its 
  length, 
  and 
  the 
  internal 
  aperture 
  has 
  become 
  a 
  

   very 
  narrow 
  and 
  elongated 
  slit. 
  The 
  first 
  abdominal 
  spiracle 
  is 
  0-19 
  mm. 
  long, 
  

   somewhat 
  broader 
  in 
  proportion 
  to 
  its 
  length 
  than 
  the 
  prothoracic. 
  Transverse 
  

   striation 
  or 
  ribbing 
  of 
  the 
  lips 
  is 
  clearly 
  noticeable. 
  Antennae 
  and 
  labial 
  palpi 
  

   remain 
  five-segmented, 
  but 
  the 
  terminal 
  segment 
  of 
  the 
  latter 
  turns 
  downwards. 
  

   There 
  is 
  a 
  slight 
  indication 
  of 
  the 
  beginning 
  of 
  a 
  division 
  of 
  the 
  tibio-tarsus 
  into 
  

   three 
  segments. 
  

  

  Fifth 
  (last) 
  Larval 
  Bnstar 
  (Plate 
  iv, 
  figs. 
  6, 
  7; 
  text-fig. 
  9). 
  

  

  The 
  last 
  instar 
  closely 
  resembles 
  the 
  preceding, 
  except 
  for 
  its 
  greater 
  size. 
  The 
  

   head 
  is 
  still 
  further 
  decreased 
  in 
  breadth 
  and 
  length 
  in 
  comparison 
  with 
  the 
  huge 
  

   prothorax 
  ; 
  its 
  breadth 
  is 
  now 
  barely 
  one-third 
  of 
  that 
  of 
  the 
  latter. 
  The 
  antennae 
  

   are 
  usually 
  five-segmented, 
  but 
  I 
  have 
  occasionally 
  noted 
  six 
  segments 
  in 
  this 
  instar 
  ; 
  

   the 
  two 
  end 
  segments 
  tend 
  to 
  turn 
  upwards. 
  The 
  labial 
  palpi 
  are 
  still 
  five-segmented, 
  

  

  Fig. 
  9. 
  Ithone 
  fusca, 
  Newm., 
  fifth 
  larval 
  instar; 
  lateral 
  view 
  of 
  head 
  and 
  foreleg, 
  with 
  

   mandible, 
  maxilla 
  and 
  tarsal 
  claws 
  left 
  unshaded 
  ( 
  X 
  20). 
  

  

  with 
  the 
  two 
  terminal 
  segments 
  turning 
  sharply 
  downwards. 
  The 
  ventral 
  portion 
  of 
  

   the 
  head 
  is 
  now 
  greatly 
  swollen 
  and 
  corrugated 
  for 
  the 
  attachment 
  of 
  the 
  maxillary 
  

   muscles. 
  The 
  upper 
  claw 
  of 
  the 
  fore 
  tarsus 
  is 
  definitely 
  longer 
  than 
  the 
  maxilla, 
  

   and 
  the 
  tibio-tarsus 
  shows 
  distinct 
  signs 
  of 
  division 
  into 
  three 
  segments, 
  of 
  which 
  

   the 
  basal 
  one 
  is 
  twice 
  as 
  long 
  as 
  the 
  other 
  two 
  together. 
  The 
  whole 
  series 
  of 
  spiracles 
  

   now 
  appears 
  as 
  a 
  row 
  of 
  transverse 
  slits, 
  very 
  much 
  longer 
  than 
  broad. 
  The 
  pro- 
  

   thoracic 
  spiracle 
  is 
  1-13 
  mm. 
  long, 
  the 
  first 
  abdominal 
  0-60 
  mm. 
  ; 
  the 
  internal 
  

   apertures 
  are 
  very 
  narrow 
  slits 
  extending 
  nearly 
  the 
  whole 
  length 
  of 
  the 
  spiracle. 
  

   The 
  edges 
  of 
  the 
  internal 
  apertures 
  can 
  be 
  seen 
  to 
  be 
  curved 
  over 
  and 
  definitely 
  

   marked 
  with 
  transverse 
  ribs, 
  as 
  are 
  also 
  the 
  lips 
  of 
  the 
  spiracle 
  itself. 
  The' 
  9th 
  

   abdominal 
  segment 
  carries 
  a 
  ring 
  of 
  conspicuous 
  dark 
  hairs, 
  not 
  noticeable 
  in 
  the 
  

   previous 
  instar. 
  

  

  Formation 
  of 
  the 
  Cocoon 
  (Plate 
  iv, 
  fig. 
  9). 
  

  

  When 
  the 
  larva 
  is 
  full-grown, 
  it 
  ceases 
  to 
  feed 
  for 
  some 
  considerable 
  time, 
  and 
  

   makes 
  its 
  way 
  down 
  to 
  a 
  somewhat 
  lower 
  level 
  where 
  the 
  soil 
  is 
  slightly 
  moister 
  

   than 
  that 
  in 
  which 
  it 
  lives 
  as 
  a 
  larva. 
  Having 
  chosen 
  a 
  suitable 
  place, 
  it 
  hollows 
  

   out 
  an 
  elongated 
  oval 
  cell 
  in 
  the 
  moist 
  soil, 
  by 
  continually 
  coiling 
  itself 
  round 
  and 
  

  

  