﻿194 
  HUBERT 
  M. 
  MORRIS. 
  

  

  Segments 
  1-7 
  with 
  a 
  stout 
  blunt 
  process 
  posterior 
  to 
  the 
  spiracle 
  ; 
  all 
  the 
  segments 
  

   except 
  last 
  with 
  a 
  slight 
  ridge 
  dorsally 
  and 
  ventrally 
  towards 
  the 
  posterior 
  margins, 
  

   the 
  ridge 
  on 
  the 
  dorsal 
  surface 
  of 
  the 
  eighth 
  segment 
  bearing 
  two 
  pairs 
  of 
  short 
  blunt 
  

   processes. 
  

  

  Note 
  on 
  Imago. 
  

  

  Out 
  of 
  278 
  larvae 
  which 
  were 
  reared, 
  including 
  those 
  killed 
  in 
  the 
  pupal 
  stage, 
  

   140 
  were 
  females 
  and 
  138 
  males. 
  This 
  slight 
  excess 
  of 
  females 
  is 
  rather 
  surprising, 
  

   as 
  in 
  the 
  field 
  there 
  usually 
  appears 
  to 
  be 
  a 
  considerable 
  excess 
  of 
  males. 
  The 
  

   males, 
  on 
  the 
  whole, 
  emerged 
  earlier 
  from 
  the 
  pupa. 
  

  

  Dilophus 
  albipennis, 
  Mg. 
  

  

  Egg- 
  

   In 
  the 
  case 
  of 
  Dilophus 
  albipennis 
  oviposition 
  is 
  carried 
  out 
  in 
  a 
  similar 
  manner 
  

   to 
  that 
  of 
  D. 
  febrilis. 
  Females 
  of 
  this 
  species 
  were 
  observed 
  to 
  oviposit 
  at 
  depths 
  of 
  

   6-5 
  cm., 
  7-5 
  cm. 
  and 
  5-0 
  cm. 
  in 
  the 
  soil. 
  

  

  The 
  eggs 
  are 
  similar 
  to 
  those 
  of 
  D. 
  febrilis, 
  but 
  are 
  slightly 
  larger, 
  being 
  about 
  

   0-62 
  mm. 
  long, 
  and 
  about 
  0-15 
  mm. 
  broad. 
  Eggs 
  laid 
  on 
  31st 
  May 
  1920 
  and 
  kept 
  

   in 
  the 
  laboratory 
  were 
  observed 
  to 
  hatch 
  on 
  30th 
  August 
  1920, 
  91 
  days 
  later. 
  Eggs 
  

   laid 
  between 
  30th 
  May 
  and 
  1st 
  June 
  1921, 
  and 
  also 
  kept 
  in 
  the 
  laboratory, 
  hatched 
  

   between 
  19th 
  September 
  and 
  22nd 
  September 
  1921, 
  112-116 
  days 
  later. 
  

  

  First 
  Stage 
  Larva 
  (newly 
  hatched). 
  

  

  The 
  first 
  stage 
  larva 
  has 
  no 
  apparent 
  difference 
  from 
  that 
  of 
  Dilophus 
  febrilis, 
  

   but 
  is 
  slightly 
  larger 
  in 
  size, 
  being 
  about 
  1 
  -3 
  mm. 
  long 
  and 
  about 
  0-16 
  mm. 
  broad. 
  

  

  Second 
  Stage 
  Larva. 
  

  

  The 
  larva 
  in 
  this 
  stage 
  appears 
  to 
  differ 
  very 
  slightly 
  from 
  that 
  of 
  Dilophus 
  

   febrilis 
  in 
  the 
  corresponding 
  stage. 
  The 
  only 
  apparent 
  difference 
  is 
  that 
  the 
  2 
  

   median 
  anterior 
  processes 
  on 
  the 
  labium 
  of 
  the 
  larva 
  of 
  D. 
  febrilis 
  are, 
  in 
  the 
  case 
  of 
  

   D. 
  albipennis, 
  replaced 
  by 
  a 
  single 
  median 
  process. 
  

  

  Third 
  Stage 
  Larva. 
  

  

  The 
  larva 
  in 
  the 
  third 
  stage 
  appears, 
  except 
  for 
  its 
  smaller 
  size, 
  to 
  be 
  almost 
  indis- 
  

   tinguishable 
  from 
  the 
  fully 
  grown 
  larva. 
  The 
  stout 
  conical 
  processes 
  of 
  the 
  body 
  are 
  

   present 
  in 
  the 
  same 
  positions 
  as 
  in 
  the 
  full-grown 
  larva. 
  

  

  The 
  tracheal 
  system 
  is 
  peripneustic, 
  with 
  ten 
  pairs 
  of 
  spiracles, 
  which 
  are 
  arranged 
  

   as 
  in 
  the 
  fully 
  grown 
  larva. 
  Each 
  spiracle 
  on 
  the 
  last 
  segment 
  has 
  two 
  openings, 
  of 
  

   which 
  the 
  posterior 
  one 
  is 
  distinctly 
  larger 
  than 
  the 
  other. 
  

  

  Fourth 
  Stage 
  Larva 
  (fully 
  grown). 
  

  

  The 
  larva 
  in 
  this 
  stage 
  is 
  distinguished 
  from 
  the 
  corresponding 
  stage 
  of 
  D. 
  febrilis 
  

   by 
  the 
  absence 
  of 
  all 
  the 
  stout 
  conical 
  processes 
  excepting 
  those 
  on 
  the 
  eleventh 
  and 
  

   twelfth 
  segments, 
  these 
  being 
  similar 
  to 
  those 
  of 
  D. 
  febrilis. 
  The 
  structure 
  of 
  the 
  

   mouth-parts 
  and 
  of 
  the 
  scales 
  on 
  the 
  cuticle 
  appears 
  to 
  be 
  identical, 
  and 
  the 
  alimentary 
  

   canal 
  is 
  also 
  similar 
  to 
  that 
  of 
  D. 
  febrilis. 
  

  

  Pupa. 
  

  

  There 
  appears 
  to 
  be 
  very 
  little 
  difference 
  in 
  either 
  sex 
  from 
  the 
  pupa 
  of 
  D. 
  febrilis. 
  

   The 
  only 
  difference 
  appears 
  to 
  be 
  that 
  the 
  processes 
  at 
  the 
  anterior 
  end 
  are 
  slightly 
  

   less 
  well 
  developed 
  in 
  this 
  species 
  than 
  in 
  the 
  former. 
  

  

  