﻿286 
  BEITISH 
  LEPIDOPTERA. 
  

  

  larva 
  of 
  this 
  species 
  on 
  Ononis. 
  Stainton 
  refers 
  thereto, 
  Ent. 
  Ann., 
  

   1856, 
  p. 
  59. 
  

  

  Variation 
  of 
  larva. 
  — 
  We 
  have 
  already 
  noted 
  two 
  colour 
  forms 
  of 
  

   larva 
  in 
  this 
  species 
  (antea, 
  pp. 
  283-285), 
  and 
  their 
  connection 
  with 
  each 
  

   other 
  (see 
  also 
  p. 
  287). 
  Porritt 
  says 
  that, 
  in 
  shape, 
  the 
  larva 
  is 
  exactly 
  

   like 
  the 
  larva 
  of 
  A. 
  punctidactyla 
  (cosmodactyla)] 
  as 
  described 
  (postea), 
  

   and, 
  as 
  in 
  that 
  species, 
  there 
  are 
  two 
  distinct 
  colour 
  forms, 
  whilst 
  inter- 
  

   mediate 
  varieties 
  occur, 
  partaking 
  more 
  or 
  less 
  of 
  the 
  characters 
  of 
  each 
  

   of 
  these 
  extreme 
  forms. 
  The 
  latter, 
  he 
  says, 
  may 
  be 
  described 
  as 
  : 
  

  

  1. 
  The 
  ground 
  colour 
  deep 
  purple; 
  head 
  yellowish-grey 
  or 
  yellowish-brown, 
  

   marked 
  on 
  the 
  crown 
  and 
  sides 
  with 
  black 
  ; 
  the 
  mandibles 
  brown 
  ; 
  mediodorsal 
  

   stripe 
  smoke-coloured 
  ; 
  subdorsal 
  lines, 
  and 
  another 
  line 
  of 
  equal 
  width 
  below 
  it, 
  

   white, 
  but 
  interrupted 
  and 
  not 
  very 
  conspicuous, 
  and, 
  below 
  these, 
  is 
  another, 
  

   scarcely 
  so 
  pale, 
  line 
  along 
  the 
  spiracles 
  ; 
  hairs, 
  and 
  the 
  distinct 
  tubercles, 
  white. 
  

   Ventral 
  surface, 
  andprolegs, 
  greenish-olive 
  ; 
  anterior 
  legs 
  shining 
  black, 
  ringed 
  with 
  

   paler. 
  

  

  2. 
  The 
  ground 
  colour 
  bright 
  pale 
  green 
  ; 
  head 
  as 
  in 
  var. 
  1 
  ; 
  the 
  dark, 
  smoky 
  

   pulsating, 
  vessel 
  — 
  in 
  some 
  specimens 
  tinged 
  with 
  pink 
  anteriorly 
  — 
  forms 
  the 
  dorsal 
  

   stripe 
  ; 
  subdorsal 
  lines 
  indistinct, 
  whitish 
  ; 
  below 
  these 
  is 
  another 
  line, 
  but 
  much 
  

   interrupted 
  and 
  broken 
  into 
  short 
  lengths 
  ; 
  there 
  are 
  no 
  lines 
  along 
  the 
  spiracular 
  

   region 
  ; 
  hairs 
  and 
  tubercles 
  white. 
  Ventral 
  surface, 
  and 
  prolegs, 
  of 
  the 
  bright 
  green 
  

   of 
  the 
  dorsal 
  area 
  ; 
  the 
  legs 
  shining 
  black, 
  ringed 
  with 
  white. 
  

  

  Comparison 
  of 
  the 
  larvae 
  of 
  Amblyptilia 
  cosmodactyla 
  and 
  A. 
  

   punctidactyla. 
  — 
  The 
  real 
  structural 
  differences 
  observable 
  in 
  these 
  larvae 
  

   have 
  already 
  been 
  noted 
  {antea, 
  p. 
  273). 
  Of 
  the 
  colour 
  differences 
  

   Porritt 
  writes 
  : 
  " 
  The 
  chief 
  points 
  of 
  distinction 
  between 
  these 
  larvae 
  

   that 
  appear 
  to 
  be 
  reliable 
  are 
  : 
  (1) 
  The 
  deep 
  purple 
  ground 
  colour 
  in 
  

   the 
  larva 
  of 
  A. 
  cosmodactyla 
  as 
  compared 
  with 
  the 
  purplish-pink 
  of 
  

   that 
  of 
  A. 
  punctidactyla. 
  (2) 
  The 
  white 
  subdorsal 
  lines 
  less 
  conspicu- 
  

   ous 
  in 
  A. 
  cosmodactyla. 
  (3) 
  The 
  head 
  yellowish-brown, 
  marked 
  with 
  

   black, 
  in 
  place 
  of 
  the 
  very 
  dark 
  sienna-brown, 
  almost 
  black, 
  in 
  A. 
  

   punctidactyla." 
  Bankes 
  is, 
  however, 
  not 
  altogether 
  satisfied 
  

   with 
  this 
  conclusion, 
  and 
  writes 
  (in 
  litt.): 
  "Although 
  the 
  imaginal 
  

   characteristics 
  of 
  punctidactyla, 
  Haw. 
  (acanthadactyla, 
  Hb.), 
  are 
  of 
  

   themselves 
  more 
  than 
  sufficient 
  to 
  prove 
  that 
  it 
  is 
  specifically 
  distinct 
  

   from 
  cosmodactyla, 
  Hb. 
  (acanthodactyla, 
  Tr.), 
  I 
  have 
  taken 
  great 
  

   trouble 
  to 
  put 
  to 
  the 
  test, 
  as 
  far 
  as 
  possible, 
  the 
  reputed 
  larval 
  differ- 
  

   ences 
  to 
  which 
  my 
  friend, 
  Mr. 
  Porritt, 
  drew 
  attention 
  (Ent. 
  Mo. 
  May., 
  

   xxiii., 
  132-3, 
  1886), 
  but, 
  it 
  must 
  be 
  confessed, 
  with 
  disappointing 
  

   results, 
  and 
  I 
  am 
  still 
  as 
  far 
  as 
  ever 
  from 
  being 
  able 
  to 
  satisfactorily 
  

   separate 
  the 
  larvae 
  of 
  these 
  species 
  by 
  colour. 
  The 
  special 
  points 
  of 
  distinc- 
  

   tion 
  noted 
  by 
  Mr. 
  Porritt 
  are 
  mentioned 
  above. 
  In 
  1892, 
  I 
  collected 
  on 
  

   Stachys 
  sylvatica, 
  probably 
  quite 
  1000 
  Alucitid 
  larvae 
  and 
  pupae, 
  mostly 
  

   in 
  the 
  former 
  stage, 
  from 
  which 
  about 
  450 
  cosmodactyla, 
  Hb., 
  and 
  21 
  

   punctidactyla, 
  Haw., 
  together 
  with 
  numbers 
  of 
  ichneumons 
  (Apanteles 
  

   fuliginosus, 
  Wesm.), 
  subsequently 
  emerged. 
  Finding 
  that 
  the 
  purplish- 
  

   pink 
  ground 
  colour 
  in 
  the 
  larva 
  was 
  frequently 
  not 
  associated 
  with 
  

   either 
  particularly 
  conspicuous 
  white 
  subdorsal 
  lines, 
  or 
  a 
  blackish 
  

   head, 
  I 
  carefully 
  sorted 
  out 
  the 
  larvae, 
  when 
  in 
  their 
  last 
  skin, 
  into 
  

   separate, 
  labelled, 
  cages, 
  to 
  test 
  these 
  supposed 
  characteristics, 
  each 
  in 
  

   turn, 
  and 
  soon 
  proved, 
  by 
  breeding 
  the 
  imagines, 
  that 
  no 
  reliance 
  

   whatever 
  could 
  be 
  placed 
  on 
  the 
  colour 
  of 
  the 
  body 
  of 
  the 
  larva, 
  or 
  

   the 
  conspicuousness 
  of 
  the 
  subdorsal 
  stripes. 
  A 
  batch, 
  separated 
  

   solely 
  because 
  their 
  subdorsal 
  stripes 
  were 
  specially 
  conspicuous, 
  

   yielded 
  many 
  cosmodactyla, 
  Hb., 
  but 
  no 
  punctidactyla, 
  Haw., 
  whereas 
  

  

  