﻿THE 
  EARLY 
  STAGES 
  OF 
  WEST 
  AFRICAN 
  MOSQUITOS. 
  

  

  427 
  

  

  Aedes 
  (Aedimorphus) 
  irritans, 
  Theo. 
  

  

  Larva. 
  — 
  The 
  larva 
  has 
  already 
  been 
  described 
  (Bull. 
  Ent. 
  Res. 
  vii, 
  p. 
  5). 
  

  

  Pupa. 
  — 
  The 
  pupa 
  is 
  of 
  moderate 
  size, 
  length 
  about 
  4 
  mm. 
  when 
  extended. 
  

  

  Cephalothorax. 
  The 
  respiratory 
  trumpets 
  (fig. 
  15, 
  a) 
  are 
  about 
  0-4 
  mm. 
  long 
  ', 
  

   they 
  are 
  rather 
  narrow 
  and 
  have 
  small 
  apertures. 
  The 
  ratio 
  of 
  the 
  length 
  of 
  the 
  meatus 
  

   to 
  the 
  total 
  length 
  of 
  the 
  trumpets 
  is 
  about 
  1 
  to 
  1-2. 
  The 
  cephalothoracic 
  setae 
  

   are 
  all 
  small, 
  the 
  dorsal 
  setae 
  being 
  small 
  tufts 
  of 
  two 
  or 
  three 
  hairs 
  about 
  half 
  the 
  

   length 
  of 
  the 
  trumpets. 
  

  

  Abdomen 
  (fig. 
  15). 
  The 
  paddles, 
  which 
  are 
  nearly 
  0-7 
  mm. 
  long, 
  are 
  oval, 
  the 
  

   ratio 
  of 
  length 
  to 
  greatest 
  breadth 
  being 
  about 
  1 
  • 
  3 
  to 
  1 
  ; 
  they 
  are 
  supported 
  by 
  a 
  

   well-developed 
  midrib 
  and 
  a 
  rather 
  ill-defined 
  external 
  buttress. 
  The 
  terminal 
  

   seta 
  is 
  single, 
  long, 
  nearly 
  one-third 
  the 
  length 
  of 
  the 
  paddle 
  (about 
  0-2 
  mm.), 
  and 
  

   usually 
  slightly 
  curved 
  at 
  its 
  extremity. 
  There 
  is 
  no 
  proper 
  fringe, 
  but 
  only 
  a 
  few 
  

   denticulations 
  along 
  the 
  external 
  borders 
  of 
  the 
  paddles. 
  

  

  The 
  lateral 
  setae 
  (A) 
  of 
  the 
  abdomen 
  are 
  highly 
  developed 
  only 
  on 
  segments 
  

   vii 
  and 
  viii 
  ; 
  on 
  the 
  other 
  segments 
  they 
  are 
  rather 
  long 
  and 
  delicate 
  single 
  or 
  

   double 
  hairs. 
  On 
  segment 
  viii 
  they 
  are 
  well-developed 
  tufts 
  composed 
  of 
  from 
  two 
  

   to 
  six 
  subplumose 
  hairs, 
  the 
  longest 
  hairs 
  being 
  aboufe 
  half 
  the 
  length 
  of 
  the 
  paddles. 
  

   On 
  segment 
  vii 
  they 
  are 
  smaller 
  tufts 
  of 
  two 
  or 
  three 
  pubescent 
  hairs. 
  The 
  sublateral 
  

   setae 
  (B) 
  on 
  the 
  dorsal 
  surface 
  of 
  segments 
  iv 
  to 
  vi 
  are 
  long, 
  reaching 
  to 
  about 
  the 
  

   posterior 
  border 
  of 
  the 
  following 
  segment, 
  single 
  or 
  double. 
  The 
  submedian 
  setae 
  

   are 
  rather 
  small 
  on 
  all 
  segments, 
  and 
  are 
  composed 
  of 
  one 
  to 
  four 
  fine 
  hairs. 
  The 
  

   other 
  setae, 
  which 
  are 
  mostly 
  small, 
  call 
  for 
  no 
  special 
  mention. 
  In 
  the 
  male 
  the 
  

   cases 
  for 
  the 
  claspers 
  are 
  very 
  large 
  and 
  long. 
  

  

  Diagnosis. 
  — 
  See 
  Aedes 
  (Ochlerotahis) 
  wellmani. 
  

  

  Habitat. 
  — 
  Accra 
  ; 
  abundant 
  at 
  all 
  times 
  of 
  the 
  year 
  in 
  crab-holes 
  and 
  in 
  collections 
  

   of 
  brackish 
  water. 
  

  

  Fig. 
  15. 
  Pupa 
  of 
  Aedes 
  irritans, 
  Theo., 
  dorsal 
  view 
  of 
  abdomen 
  : 
  a, 
  trumpet. 
  

  

  Aedes 
  (Finlaya) 
  wellmani, 
  Theo. 
  

  

  Larva. 
  — 
  Head 
  not 
  strongly 
  chitinised 
  and 
  not 
  large 
  relatively 
  to 
  the 
  thorax. 
  

   Mouth-brushes 
  rather 
  conspicuous. 
  The 
  antenna 
  is 
  stout 
  and 
  curved, 
  with 
  the 
  

   convexity 
  external, 
  sparsely 
  covered 
  with 
  spicules 
  ; 
  hair-tuft 
  situated 
  about 
  three- 
  

   seventh's 
  of 
  the 
  length 
  of 
  the 
  shaft 
  from 
  the 
  base, 
  and 
  composed 
  of 
  six 
  or 
  more 
  

   subplumose 
  hairs. 
  The 
  shaft 
  of 
  the 
  antenna 
  tapers 
  gradually 
  from 
  the 
  insertion 
  

   of 
  the 
  hair-tuft 
  to 
  the 
  apex. 
  The 
  ante-antennal 
  tuft 
  (outer 
  post-antennal 
  of 
  Lang) 
  

  

  