﻿THE 
  LARVAL 
  AND 
  PUPAL 
  STAGES 
  OF 
  THE 
  BIBIONIDAE 
  — 
  PART 
  II. 
  

  

  191 
  

  

  i 
  The 
  body 
  is 
  light 
  brown 
  in 
  colour 
  and 
  almost 
  cylindrical, 
  but 
  somewhat 
  flattened 
  

   dorso-ventrally 
  ; 
  it 
  is 
  normally 
  slightly 
  curved, 
  with 
  the 
  ventral 
  surface 
  concave, 
  

   and 
  is 
  divided 
  into 
  12 
  segments, 
  of 
  which 
  the 
  first 
  is 
  the 
  largest. 
  

  

  Fig. 
  3. 
  Right 
  mandible 
  of 
  larva 
  cf 
  

   Dilophus 
  fcbrilis, 
  X 
  140. 
  

  

  Fig. 
  4. 
  Left 
  maxilla 
  of 
  same, 
  

   ventral 
  view, 
  x 
  140. 
  

  

  There 
  are 
  10 
  pairs 
  of 
  spiracles,* 
  a 
  pair 
  on 
  each 
  segment, 
  except 
  the 
  second 
  and 
  

   eleventh, 
  and 
  they 
  project 
  slightly 
  from 
  the 
  body. 
  The 
  spiracles 
  on 
  the 
  first 
  segment 
  

   are 
  situated 
  laterally 
  near 
  the 
  posterior 
  margin 
  of 
  the 
  segment 
  ; 
  those 
  on 
  segments 
  

   3-10 
  are 
  situated 
  laterally 
  near 
  the 
  anterior 
  margins, 
  and 
  are 
  about 
  half 
  the 
  size 
  

   of 
  those 
  on 
  the 
  first 
  segment. 
  The 
  spiracles 
  on 
  the 
  twelfth 
  segment 
  are 
  in 
  a 
  more 
  

   dorsal 
  position 
  near 
  its 
  anterior 
  margin, 
  and 
  are 
  about 
  twice 
  the 
  size 
  of 
  those 
  on 
  the 
  

   first 
  segment. 
  Each 
  posterior 
  spiracle 
  has 
  three 
  openings 
  (fig. 
  7), 
  although 
  there 
  

   appears 
  to 
  be 
  an 
  occasional 
  tendency 
  for 
  two 
  of 
  the 
  openings 
  to 
  fuse, 
  so 
  that 
  the 
  

   spiracle 
  then 
  has 
  only 
  two 
  openings. 
  

  

  Fig. 
  5. 
  Labium 
  of 
  larva 
  of 
  D.febrilis, 
  

   ventral 
  view, 
  x 
  140. 
  

  

  Fig. 
  6. 
  Antenna 
  of 
  same, 
  X 
  S70. 
  

  

  Each 
  segment 
  bears 
  a 
  few 
  stout 
  conical 
  processes 
  similar 
  to 
  those 
  of 
  Bibio 
  larvae, 
  

   but 
  in 
  this 
  species 
  they 
  are 
  fewer 
  in 
  number 
  and 
  smaller. 
  The 
  first 
  segment 
  bears 
  

   a 
  single 
  pair 
  of 
  processes 
  of 
  moderate 
  size, 
  each 
  process 
  lying 
  immediately 
  above 
  the 
  

   spiracle. 
  Segments 
  2-10 
  bear 
  each 
  a 
  similar 
  pair 
  of 
  processes 
  in 
  a 
  dorso-lateral 
  

  

  position 
  at 
  about 
  the 
  middle 
  of 
  

  

  the 
  segment. 
  

  

  In 
  addition, 
  segments 
  4-10 
  bear 
  

  

  a 
  smaller 
  pair 
  of 
  processes 
  just 
  posterior 
  to 
  the 
  spiracle. 
  The 
  eleventh 
  segment 
  

   bears 
  a 
  row 
  of 
  6 
  processes 
  on 
  its 
  dorsal 
  surface, 
  somewhat 
  behind 
  the 
  middle 
  of 
  the 
  

   segment, 
  and 
  the 
  twelfth 
  segment 
  has 
  a 
  row 
  of 
  4 
  rather 
  larger 
  processes 
  near 
  its 
  

   posterior 
  margin. 
  

  

  * 
  In 
  the 
  account 
  of 
  the 
  larva 
  of 
  B. 
  marci 
  (Morris, 
  1921), 
  owing 
  apparently 
  to 
  a 
  flaw 
  in 
  the 
  

   block, 
  the 
  spiracles 
  on 
  the 
  fifth 
  and 
  sixth 
  segments 
  are 
  omitted 
  in 
  fig. 
  3. 
  

  

  