﻿106 
  RUPERT 
  W. 
  JACK 
  — 
  TSETSE 
  FLY 
  

  

  in 
  the 
  case 
  of 
  palpalis, 
  Koch 
  has 
  shown 
  that, 
  in 
  the 
  presence 
  of 
  other 
  sources 
  of 
  blood, 
  

   birds 
  are 
  not 
  laid 
  under 
  contribution 
  to 
  any 
  great 
  extent, 
  and 
  his 
  observations 
  have 
  

   been 
  confirmed 
  by 
  Bruce. 
  Similar 
  observations 
  do 
  not 
  seem 
  to 
  have 
  been 
  made 
  with 
  

   morsitans, 
  but 
  it 
  should 
  be 
  noted 
  that 
  this 
  species 
  has 
  little 
  opportunity 
  of 
  feeding 
  

   upon 
  the 
  quiescent 
  water-loving 
  birds 
  suggested 
  as 
  the 
  source 
  of 
  the 
  avian 
  blood 
  found 
  

   in 
  palpalis. 
  Moreover, 
  the 
  tsetse's 
  habit 
  of 
  awaiting 
  its 
  prey 
  not 
  far 
  from 
  the 
  ground 
  

   renders 
  it 
  probable 
  that 
  the 
  vast 
  majority 
  of 
  birds 
  come 
  comparatively 
  rarely 
  within 
  

   the 
  ken 
  of 
  the 
  fly.* 
  Small 
  birds, 
  also, 
  in 
  addition 
  to 
  their 
  restlesness, 
  activity 
  and 
  

   tendency 
  to 
  catch 
  insects, 
  probably 
  have 
  but 
  little 
  power 
  of 
  attracting 
  tsetse, 
  for 
  

   there 
  is 
  some 
  evidence 
  to 
  show 
  that 
  the 
  size 
  of 
  an 
  animal 
  and 
  the 
  amount 
  of 
  

   disturbance 
  created 
  in 
  moving 
  about 
  have 
  a 
  direct 
  influence 
  on 
  the 
  number 
  of 
  tsetse 
  

   attracted, 
  at 
  least 
  in 
  the 
  case 
  of 
  morsitans. 
  It 
  would 
  in 
  fact 
  seem 
  that 
  the 
  distance 
  

   a 
  tsetse 
  is 
  led 
  by 
  scent 
  alone 
  is 
  a 
  comparatively 
  short 
  one. 
  The 
  writer 
  has 
  frequently 
  

   had 
  the 
  experience 
  that 
  when 
  sitting 
  quietly 
  in 
  a 
  fly-belt 
  few 
  tsetse 
  would 
  be 
  in 
  

   attendance, 
  but 
  that 
  a 
  movement 
  of 
  only 
  a 
  few 
  yards 
  brought 
  a 
  considerable 
  accession 
  

   of 
  numbers, 
  the 
  newcomers 
  showing 
  a 
  desire 
  to 
  bite 
  that 
  proved 
  they 
  were 
  hungry. 
  

   On 
  the 
  other 
  hand, 
  movement 
  through 
  infested 
  forest 
  invariably 
  attracts 
  a 
  number 
  

   of 
  the 
  flies, 
  even 
  when 
  it 
  is 
  as 
  soundless 
  as 
  progress 
  along 
  a 
  path 
  on 
  a 
  bicycle. 
  The 
  

   flies 
  in 
  such 
  circumstances 
  do 
  not 
  always 
  evince 
  a 
  desire 
  to 
  feed, 
  but 
  on 
  the 
  other 
  hand 
  

   they 
  quite 
  commonly 
  do 
  so. 
  From 
  this 
  it 
  appears 
  that 
  the 
  range 
  of 
  sight 
  is 
  greater 
  

   than 
  that 
  of 
  scent, 
  and 
  that 
  large 
  moving 
  bodies 
  constitute 
  a 
  particular 
  attraction. 
  

   If 
  this 
  is 
  the 
  main 
  method 
  by 
  which 
  flies 
  are 
  attracted, 
  the 
  range 
  of 
  attraction 
  of 
  an 
  

   animal 
  should, 
  within 
  certain 
  limits, 
  vary 
  in 
  direct 
  ratio 
  with 
  its 
  size, 
  and 
  one 
  can 
  

   understand 
  that, 
  apart 
  from 
  all 
  other 
  considerations, 
  small 
  mammals, 
  small 
  birds 
  

   and 
  small 
  reptiles 
  could 
  on 
  this 
  account 
  alone 
  form 
  only 
  a 
  casual 
  source 
  of 
  sustenance. 
  

   There 
  are, 
  however, 
  certain 
  birds 
  which 
  live 
  almost 
  entirely 
  on 
  the 
  ground, 
  are 
  of 
  

   sufficient 
  size 
  to 
  attract 
  tsetse 
  from 
  some 
  distance 
  by 
  vision, 
  and 
  are 
  often 
  found 
  in 
  

   great 
  abundance 
  in 
  the 
  particular 
  haunts 
  of 
  the 
  fly. 
  These 
  comprise 
  several 
  species 
  

   known 
  as 
  game 
  birds, 
  and 
  include 
  Numida, 
  Pternistes, 
  Francolinus 
  and 
  others. 
  The 
  

   fact 
  of 
  tsetse 
  feeding 
  on 
  fowls 
  in 
  captivity 
  would 
  seem 
  to 
  show 
  that 
  attempts 
  would 
  

   be 
  made 
  to 
  feed 
  on 
  other 
  gallinaceous 
  birds 
  in 
  a 
  state 
  of 
  nature, 
  at 
  least 
  when 
  pressed 
  

   by 
  hunger. 
  The 
  writer 
  has, 
  nevertheless, 
  found 
  on 
  entering 
  a 
  limited 
  belt 
  where 
  

   enormous 
  numbers 
  of 
  game 
  birds 
  were 
  congregated, 
  the 
  flies 
  were 
  as 
  eager 
  for 
  

   mammalian 
  blood 
  as 
  elsewhere, 
  and 
  the 
  collapsed 
  state 
  of 
  the 
  abdomen 
  showed 
  that 
  

   they 
  had 
  not 
  fed 
  to 
  the 
  full 
  for 
  days. 
  At 
  this 
  spot 
  the 
  birds 
  rose 
  from 
  the 
  grass 
  at 
  

   almost 
  every 
  step, 
  and 
  if 
  the 
  flies 
  were 
  in 
  the 
  habit 
  of 
  finding 
  the 
  birds 
  and 
  feeding 
  

   on 
  them 
  there 
  was 
  certainly 
  not 
  the 
  least 
  difficulty 
  in 
  every 
  fly 
  doing 
  so, 
  nor 
  

   any 
  apparent 
  reason 
  for 
  the 
  presence 
  of 
  swarms 
  of 
  desperately 
  hungry 
  individuals. 
  

   There 
  is 
  therefore 
  some 
  ground 
  for 
  belief 
  that 
  for 
  some 
  constitutional 
  cause, 
  such 
  as 
  

   their 
  conformation, 
  their 
  armature 
  of 
  feathers, 
  their 
  activity, 
  their 
  habit 
  of 
  pecking 
  

   at 
  insects, 
  or 
  such 
  causes 
  combined, 
  birds 
  as 
  a 
  class 
  do 
  not 
  form 
  a 
  very 
  suitable 
  source 
  

   of 
  sustenance 
  to 
  tsetse. 
  f 
  That 
  some 
  such 
  disability 
  exists 
  in 
  respect 
  to 
  most 
  other 
  

  

  * 
  [In 
  a 
  series 
  of 
  captured 
  G. 
  morsitans 
  examined 
  by 
  Lloyd 
  in 
  Northern 
  Rhodesia, 
  he 
  

   found 
  that 
  of 
  the 
  specimens 
  in 
  which 
  the 
  blood 
  content 
  could 
  be 
  identified 
  15 
  per 
  cent, 
  

   contained 
  non 
  -mammalian 
  blood. 
  — 
  Ed.] 
  

  

  t 
  On 
  admittedly 
  somewhat 
  slender 
  grounds 
  Mr. 
  Lloyd, 
  of 
  the 
  Luangwa 
  Sleeping 
  

   Sickness 
  Commission, 
  is 
  inclined 
  to 
  the 
  belief 
  that 
  morsitans 
  does 
  not 
  thrive 
  on 
  avian 
  

   blood 
  in 
  the 
  same 
  way 
  as 
  it 
  does 
  on 
  mammalian. 
  — 
  Bull. 
  Ent. 
  Research, 
  iii, 
  part 
  3. 
  

  

  