﻿THE 
  TABANIDAE 
  OF 
  SOUTHERN 
  NYASALAND. 
  291 
  

  

  various 
  Muscid 
  flies, 
  collected 
  from 
  the 
  carcases 
  of 
  rats, 
  etc., 
  trapped 
  for 
  the 
  purpose. 
  

   These 
  larvae 
  buried 
  themselves 
  at 
  once 
  in 
  the 
  mud, 
  where 
  they 
  were 
  apparently- 
  

   consumed 
  by 
  the 
  Tabanid 
  larvae, 
  which 
  thrived 
  under 
  these 
  conditions. 
  The 
  

   larger 
  species 
  also 
  greedily 
  attacked 
  the 
  freshly-killed 
  bodies 
  of 
  small 
  tadpoles, 
  

   molluscs 
  and 
  fish-fry 
  placed 
  on 
  the 
  surface 
  of 
  the 
  mud, 
  though 
  they 
  were 
  seldom 
  

   actually 
  seen 
  to 
  do 
  this, 
  unless 
  examined 
  at 
  night. 
  It 
  was 
  found 
  in 
  most 
  cases 
  that 
  

   the 
  Tabanid 
  larvae 
  did 
  best 
  in 
  mud 
  or 
  sand 
  (this 
  point 
  being 
  usually 
  decided 
  

   by 
  the 
  conditions 
  under 
  which 
  they 
  had 
  been 
  found) 
  which 
  was 
  very 
  wet, 
  but 
  

   without 
  standing 
  water 
  on 
  the 
  surface. 
  Before 
  the 
  larvae 
  have 
  reached 
  their 
  full 
  

   growth, 
  which 
  in 
  many 
  cases 
  signifies 
  the 
  beginning 
  of 
  a 
  resting 
  period, 
  they 
  

   usually 
  lie 
  buried 
  in 
  the 
  mud, 
  head 
  downwards, 
  with 
  their 
  syphons 
  projecting 
  

   immediately 
  above 
  the 
  surface 
  of 
  the 
  mud 
  or 
  of 
  a 
  shallow 
  layer 
  of 
  water 
  above 
  it, 
  

   if 
  it 
  be 
  present. 
  In 
  the 
  resting 
  stage 
  the 
  syphons 
  do 
  not 
  seem 
  to 
  be 
  made 
  use 
  of 
  

   and 
  the 
  larvae 
  remain 
  several 
  inches 
  below 
  the 
  surface 
  for 
  weeks 
  or 
  even 
  months. 
  

   This 
  is 
  presumably 
  an 
  adaptation 
  connected 
  with 
  a 
  climate 
  in 
  which 
  there 
  is 
  a 
  

   very 
  marked 
  dry 
  season, 
  and 
  consequently, 
  a 
  risk 
  of 
  the 
  mud 
  in 
  which 
  they 
  are 
  

   lying, 
  more 
  or 
  less 
  drying 
  up. 
  

  

  If 
  it 
  is 
  necessary 
  to 
  transport 
  for 
  any 
  distance 
  larvae 
  which 
  have 
  not 
  reached 
  

   the 
  resting 
  stage, 
  it 
  is 
  important 
  that 
  the 
  jars, 
  etc., 
  in 
  which 
  they 
  are 
  placed 
  

   should 
  only 
  contain 
  wet 
  mud 
  or 
  sand 
  and 
  that 
  there 
  should 
  be 
  no 
  standing 
  

   water 
  on 
  the 
  surface. 
  Some 
  of 
  my 
  earliest 
  captures, 
  which 
  had 
  to 
  be 
  transported 
  

   some 
  50 
  or 
  60 
  miles 
  from 
  the 
  Shire 
  Kiver 
  to 
  Mlanje, 
  were 
  nearly 
  all 
  lost 
  from 
  this 
  

   cause, 
  the 
  larvae 
  being 
  apparently 
  drowned 
  by 
  the 
  movements 
  of 
  the 
  water 
  on 
  

   the 
  surface. 
  

  

  Pupation 
  appears 
  to 
  take 
  place 
  in 
  normal 
  circumstances 
  an 
  inch 
  or 
  more 
  below 
  

   the 
  surface, 
  though 
  occasionally 
  in 
  captivity, 
  individuals 
  pupated 
  lying 
  horizontally 
  

   upon 
  it. 
  The 
  pupa 
  is 
  normally 
  upright 
  in 
  the 
  mud 
  and 
  after 
  pupation, 
  as 
  soon 
  

   as 
  the 
  case 
  has 
  hardened, 
  it 
  works 
  its 
  way 
  up 
  by 
  means 
  of 
  its 
  rings 
  of 
  spines 
  and 
  

   the 
  aster 
  (a 
  name 
  proposed 
  for 
  the 
  terminal 
  whorl 
  of 
  spines), 
  until 
  the 
  pupal 
  head 
  

   lies 
  just 
  below 
  the 
  surface, 
  being 
  often 
  visible 
  from 
  above. 
  The 
  pupa 
  at 
  first 
  is 
  

   usually 
  of 
  a 
  pale 
  yellowish 
  or 
  greenish 
  colour, 
  but 
  darkens 
  as 
  the 
  imago 
  develops 
  

   within, 
  the 
  process 
  beginning 
  with 
  the 
  eyes. 
  

  

  In 
  normally 
  fine 
  weather 
  the 
  imagines 
  of 
  all 
  species 
  almost 
  invariably 
  emerged 
  

   between 
  noon 
  and 
  3 
  p.m. 
  They 
  were 
  more 
  irregular 
  during 
  spells 
  of 
  dull 
  and 
  rainy 
  

   weather. 
  The 
  process 
  of 
  emergence 
  seems 
  to 
  be 
  quite 
  similar 
  in 
  individuals 
  of 
  all 
  

   genera, 
  whether 
  Chrysops, 
  Haematopota 
  or 
  Tabanus. 
  The 
  head 
  of 
  the 
  pupa 
  splits 
  

   in 
  the 
  median 
  dorsal 
  line 
  and 
  the 
  imago 
  rapidly 
  emerges 
  until 
  only 
  the 
  end 
  of 
  the 
  

   abdomen, 
  which 
  is 
  at 
  first 
  enormously 
  elongated, 
  remains 
  in 
  the 
  pupa-case. 
  The 
  

   wings 
  at 
  this 
  stage 
  are 
  milky 
  white 
  and 
  the 
  darker 
  markings, 
  if 
  any, 
  are 
  barely 
  

   visible. 
  The 
  imago 
  usually 
  remains 
  in 
  this 
  position 
  for 
  some 
  two 
  or 
  three 
  minutes 
  

   before 
  completely 
  leaving 
  the 
  pupa-case. 
  It 
  is 
  capable 
  of 
  flight 
  very 
  soon 
  after 
  this, 
  

   but 
  if 
  undisturbed 
  sits 
  for 
  about 
  half 
  an 
  hour 
  on 
  any 
  suitable 
  object 
  near 
  by 
  while 
  

   the 
  wings 
  dry 
  and 
  assume 
  their 
  normal 
  coloration 
  and 
  the 
  abdomen 
  its 
  normal 
  

   shape. 
  During 
  this 
  period 
  several 
  drops 
  of 
  a 
  milky 
  white 
  fluid 
  are 
  passed 
  per 
  

   anum. 
  Flight, 
  however, 
  seems 
  invariably 
  to 
  take 
  place 
  before 
  the 
  wings 
  are 
  

   (C120) 
  B 
  2 
  

  

  