﻿THE 
  BIONOMICS 
  OF 
  SOME 
  MALAYAN 
  ANOPHELINES. 
  149 
  

  

  at 
  the 
  bottom, 
  usually 
  ventral 
  surface 
  uppermost 
  with 
  the 
  " 
  tail 
  " 
  at 
  an 
  angle 
  of 
  

   45 
  degrees 
  to 
  the 
  body, 
  an 
  attitude 
  often 
  seen 
  in 
  dead 
  larvae, 
  whereby 
  it 
  would 
  almost 
  

   appear 
  that 
  they 
  might 
  be 
  hoping 
  to 
  deceive 
  enemies 
  in 
  search 
  of 
  them. 
  It 
  was 
  noted 
  

   that 
  a 
  family 
  of 
  larvae 
  of 
  A. 
  hyrcanus 
  var. 
  paeditaeniatus 
  were 
  particularly 
  wary, 
  

   remaining 
  under 
  the 
  turbid 
  water 
  so 
  long 
  (some 
  for 
  two 
  minutes) 
  that 
  it 
  would 
  have 
  

   been 
  easy 
  for 
  any 
  inexperienced 
  passer-by 
  to 
  doubt 
  their 
  existence 
  even 
  in 
  bowls. 
  

   The 
  larvae 
  of 
  A 
  . 
  barbirostris 
  seemed 
  to 
  be 
  less 
  alert 
  than 
  these 
  until 
  a 
  rather 
  later 
  age, 
  

   but 
  were 
  yet 
  quite 
  wary 
  in 
  the 
  last 
  moult. 
  A 
  little 
  experience 
  with 
  a 
  family 
  of 
  these 
  

   will 
  probably 
  be 
  always 
  remembered 
  by 
  the 
  writer. 
  There 
  had 
  been 
  at 
  first 
  considerable 
  

   difficulty 
  in 
  breeding 
  the 
  species, 
  most 
  of 
  the 
  larvae 
  in 
  families 
  dying 
  off 
  and 
  only 
  a 
  

   few 
  attaining 
  maturity. 
  Trial 
  with 
  a 
  new 
  food 
  material 
  seemed 
  to 
  afford 
  promise 
  of 
  

   far 
  better 
  results, 
  for 
  out 
  of 
  a 
  very 
  large 
  family 
  of 
  half-grown 
  larvae 
  none 
  had 
  died 
  for 
  

   days, 
  and 
  all 
  were 
  active. 
  It 
  was 
  with 
  no 
  small 
  dismay, 
  therefore, 
  that 
  on 
  approaching 
  

   the 
  basins 
  containing 
  them, 
  a 
  day 
  or 
  two 
  before 
  the 
  expected 
  pupations, 
  many 
  were 
  

   seen, 
  lying 
  at 
  the 
  bottom 
  in 
  various 
  position 
  of 
  distortion 
  and 
  upside-down. 
  At 
  each 
  

   previous 
  inspection 
  all 
  had 
  been 
  quietly 
  feeding 
  at 
  the 
  surface, 
  and 
  it 
  was 
  felt 
  that 
  

   those 
  at 
  the 
  bottom 
  must 
  be 
  dead, 
  for 
  no 
  movement 
  at 
  all 
  was 
  made. 
  However, 
  on 
  

   an 
  attempt 
  to 
  move 
  them, 
  the 
  apparently 
  dead 
  larvae 
  scuttled 
  off 
  elsewhere 
  with 
  

   great 
  activity. 
  

  

  The 
  alarm 
  manifested 
  by 
  the 
  larvae 
  would 
  seem 
  to 
  suggest 
  that 
  their 
  instinct 
  had 
  

   apprised 
  them 
  of 
  menace 
  both 
  from 
  above 
  and 
  from 
  the 
  water 
  itself 
  ; 
  indeed, 
  the 
  

   polymorphism 
  of 
  species 
  (A. 
  hyrcanus 
  and 
  A. 
  barbirostris 
  in 
  particular) 
  breeding 
  by 
  

   preference 
  in 
  large 
  open 
  sheets 
  of 
  water, 
  affording 
  many 
  varied 
  conditions 
  of 
  environ- 
  

   ment 
  (to 
  which 
  the 
  variations 
  both 
  of 
  colour 
  and 
  pattern 
  are 
  due, 
  in 
  part 
  at 
  all 
  events 
  

   — 
  as 
  some 
  experiments 
  by 
  the 
  writer, 
  as 
  yet 
  unpublished, 
  have 
  shown) 
  would 
  seem 
  

   to 
  suggest 
  constant 
  attack 
  from 
  above. 
  From 
  lack 
  of 
  opportunity 
  the 
  nature 
  of 
  this 
  

   attack 
  was 
  not, 
  unfortunately, 
  enquired 
  into 
  very 
  fully 
  ; 
  but 
  Anthomyiid 
  flies 
  of 
  

   the 
  genus 
  Lispa, 
  described 
  by 
  Atkinson 
  in 
  Hong 
  Kong 
  and 
  by 
  the 
  writer 
  in 
  Nyasaland 
  

   as 
  attacking 
  Culicid 
  larvae, 
  were 
  present 
  often 
  in 
  very 
  great 
  abundance 
  on 
  the 
  water 
  

   at 
  its 
  edge, 
  and 
  may 
  well 
  take 
  some 
  toll 
  of 
  the 
  Anopheline 
  larvae. 
  Furthermore, 
  

   particular 
  dragonflies 
  were 
  seen 
  frequently 
  stooping 
  over 
  the 
  water, 
  head 
  down, 
  as 
  

   if 
  at 
  some 
  prey 
  on 
  the 
  surface. 
  It 
  is 
  not 
  beyond 
  the 
  powers 
  of 
  dragonflies 
  to 
  take 
  

   creeping 
  insects 
  (the 
  writer 
  has 
  repeatedly 
  watched 
  a 
  particular 
  species 
  in 
  Nyasaland 
  

   catching 
  ants), 
  and 
  so 
  these 
  may 
  well 
  be 
  among 
  the 
  agents 
  which 
  cause 
  the 
  larvae 
  of 
  

   Anophelines 
  to 
  feel 
  apprehension. 
  

  

  Other 
  Natural 
  Enemies 
  of 
  Larvae. 
  

  

  It 
  is 
  said 
  that 
  the 
  larvae 
  of 
  Anophelines 
  do 
  not 
  as 
  a 
  rule 
  coexist 
  in 
  breeding-places 
  

   with 
  those 
  of 
  Chironomidae. 
  This 
  is 
  true 
  of 
  small 
  muddy 
  pools 
  in 
  the 
  Malay 
  States, 
  

   in 
  some 
  of 
  which 
  the 
  Chironomidae 
  larvae 
  exist 
  in 
  enormous 
  numbers. 
  So 
  far 
  as 
  could 
  

   be 
  ascertained 
  their 
  influence 
  on 
  the 
  Anophelines 
  is 
  indirect 
  only 
  ; 
  for, 
  in 
  basins, 
  the 
  

   Chironomids 
  collected 
  up 
  all 
  the 
  floating 
  algae 
  with 
  such 
  assiduity, 
  for 
  the 
  purpose 
  of 
  

   forming 
  their 
  larva 
  cases, 
  that 
  the 
  Anophelines 
  soon 
  became 
  reduced 
  to 
  the 
  verge 
  of 
  

   starvation. 
  No 
  direct 
  attack 
  was 
  ever 
  seen. 
  

  

  In 
  certain 
  ponds 
  in 
  which 
  no 
  Anopheline 
  larvae 
  were 
  ever 
  found 
  in 
  the 
  course 
  of 
  

   searches 
  made 
  between 
  April 
  and 
  July, 
  certain 
  predacious 
  insects 
  existed 
  in 
  great 
  

   numbers, 
  particularly 
  the 
  larvae 
  of 
  Neuroptera, 
  which 
  were 
  never 
  bred 
  out 
  (but 
  were 
  

   not 
  those 
  of 
  dragonflies), 
  and 
  some 
  Belostomatidae, 
  the 
  females 
  of 
  which 
  were 
  

   frequently 
  seen 
  with 
  masses 
  of 
  ova 
  on 
  their 
  elytra. 
  The 
  Neuroptera 
  in 
  particular 
  

   were 
  highly 
  predacious, 
  devouring 
  each 
  other 
  when 
  confined 
  in 
  basins, 
  even 
  though 
  

   supplied 
  with 
  ample 
  other 
  food 
  material 
  in 
  the 
  shape 
  of 
  Culicid 
  larvae. 
  

  

  The 
  writer 
  has 
  to 
  acknowledge 
  his 
  obligation 
  to 
  the 
  most 
  efficient 
  staff, 
  trained 
  by 
  

   Dr. 
  H. 
  P. 
  Hacker, 
  the 
  officer 
  in 
  charge 
  of 
  the 
  Malaria 
  Bureau, 
  and 
  particularly 
  to 
  

   Mr. 
  Daniel 
  Rajamoney 
  and 
  Mr. 
  M. 
  C. 
  Chuen, 
  for 
  their 
  untiring 
  enthusiasm 
  and 
  patience 
  

   in 
  carrying 
  out 
  the 
  details 
  of 
  the 
  tedious 
  breeding 
  experiments. 
  

  

  