﻿ENTOMOLOGICAL 
  ASPECTS 
  OF 
  AN 
  OUTBREAK 
  OF 
  SLEEPING 
  SICKNESS. 
  333 
  

  

  an 
  excess 
  of 
  females. 
  A 
  complicating 
  factor 
  in 
  such 
  experiments 
  was 
  suggested 
  

   by 
  the 
  fact 
  that 
  on 
  several 
  occasions 
  in 
  the 
  Simiyu 
  area 
  it 
  seemed 
  that 
  females 
  were 
  

   merely 
  slower 
  to 
  attack 
  than 
  males. 
  Thus 
  in 
  one 
  case 
  the 
  first 
  six 
  flies 
  were 
  all 
  

   males, 
  but 
  continuing 
  to 
  stand 
  in 
  the 
  same 
  place, 
  our 
  final 
  bag 
  was 
  11 
  ihales 
  and 
  

   9 
  females. 
  A 
  marked 
  excess 
  of 
  males 
  became 
  the 
  rule 
  after 
  we 
  had, 
  at 
  Ngasamo, 
  

   passed 
  out 
  into 
  the 
  country 
  of 
  unimpeded 
  movement 
  of 
  game. 
  The 
  grass 
  was 
  

   unburned 
  in 
  this 
  area 
  also, 
  so 
  that 
  it 
  was 
  no 
  difficulty 
  connected 
  with 
  this 
  that 
  

   caused 
  the 
  flies 
  to 
  be 
  more 
  eager 
  for 
  food 
  in 
  the 
  enclosed 
  area 
  than 
  here. 
  

  

  A 
  striking 
  point 
  about 
  this 
  fly 
  was 
  that 
  it 
  showed 
  no 
  appreciable 
  preference 
  for 
  

   cattle 
  as 
  against 
  man. 
  My 
  fly-boys 
  also 
  remarked 
  with 
  surprise 
  on 
  this 
  contrast 
  

   with 
  all 
  their 
  previous 
  experience. 
  On 
  several 
  occasions 
  when 
  I 
  was 
  present 
  the 
  

   initial 
  attack 
  was 
  on 
  the 
  cattle 
  ; 
  the 
  fly 
  then 
  spreading 
  from 
  them 
  to 
  the 
  men 
  around 
  

   and 
  being 
  mostly 
  caught 
  on 
  the 
  latter. 
  On 
  numerous 
  occasions 
  the 
  natives 
  actually 
  

   catching 
  at 
  the 
  cattle 
  had 
  no 
  flies 
  on 
  them, 
  while 
  the 
  cattle 
  and 
  the 
  men 
  five 
  or 
  six 
  

   yards 
  away 
  were 
  attacked, 
  so 
  that 
  it 
  was 
  likely 
  that 
  the 
  cattle 
  acted 
  as 
  some 
  protection 
  

   to 
  the 
  natives 
  actually 
  working 
  with 
  them 
  ; 
  but 
  this, 
  and 
  the 
  possibility 
  that 
  the 
  

   cattle 
  did 
  tend 
  to 
  induce 
  more 
  flies 
  to 
  leave 
  the 
  bush 
  in 
  the 
  first 
  instance, 
  is 
  the 
  most 
  

   that 
  can 
  be 
  said, 
  and 
  the 
  tsetse 
  boys 
  themselves 
  considered 
  that 
  the 
  fly 
  liked 
  man 
  

   better. 
  I 
  was 
  myself 
  much 
  reminded 
  during 
  these 
  observations 
  of 
  my 
  experiments 
  

   on 
  birds. 
  These, 
  when 
  hungry 
  enough, 
  made 
  no 
  choice 
  between 
  insect 
  and 
  insect 
  

   when 
  laid 
  down 
  together, 
  but 
  took 
  them 
  as 
  they 
  came, 
  the 
  most 
  " 
  nauseous 
  " 
  species 
  

   .as 
  readily 
  as 
  the 
  more 
  " 
  palatable," 
  except 
  that 
  they 
  preferred 
  the 
  largest. 
  

  

  About 
  Ngasamo, 
  in 
  spots 
  where 
  game 
  was 
  present, 
  boys 
  working 
  with 
  cattle 
  

   brought 
  in 
  nearly 
  the 
  same 
  large 
  proportion 
  of 
  males 
  as 
  boys 
  working 
  without. 
  

  

  In 
  general, 
  I 
  am 
  inclined 
  to 
  regard 
  this 
  tsetse 
  as 
  having 
  become, 
  under 
  the 
  local 
  

   conditions, 
  an 
  unusually 
  dangerous 
  fly 
  to 
  man. 
  Mr. 
  G. 
  G. 
  Griffiths 
  also 
  testifies 
  

   to 
  the 
  savageness 
  of 
  its 
  attacks 
  in 
  the 
  Chinyanga 
  fly-belt. 
  

  

  XI. 
  — 
  Breeding-places 
  of 
  the 
  Fly. 
  

  

  The 
  high 
  grass 
  everywhere 
  made 
  it 
  difficult 
  to 
  find 
  logs, 
  but 
  in 
  the 
  thickets 
  

   (mainly 
  of 
  a 
  xerophilous 
  type 
  and 
  characterised 
  by 
  Sanseviera) 
  a 
  considerable 
  number 
  

   of 
  puparia 
  were 
  found 
  under 
  leaning 
  trunks 
  or 
  at 
  the 
  bases 
  of 
  standing 
  trees 
  (especially 
  

   Albizzia 
  hypoleuca, 
  PI. 
  xvi, 
  fig. 
  1), 
  as 
  well 
  as 
  under 
  woody 
  scrub 
  and 
  the 
  heavy 
  coils 
  of 
  

   lianas. 
  Most 
  were 
  empty, 
  as 
  on 
  the 
  granite 
  kopjes. 
  In 
  its 
  apparent 
  partiality 
  for 
  

   thickets 
  as 
  a 
  place 
  of 
  deposition 
  the 
  fly 
  would 
  appear 
  to 
  resemble 
  pallidipcs 
  and 
  differ 
  

   from 
  typical 
  morsitans, 
  for, 
  in 
  the 
  west 
  of 
  the 
  territory 
  at 
  any 
  rate, 
  few 
  morsitans 
  

   pupae 
  but 
  many 
  pallidipes 
  are 
  found 
  in 
  these 
  thickets, 
  while 
  under 
  the 
  logs 
  in 
  the 
  

   grass 
  outside 
  them 
  the 
  proportions 
  are 
  reversed. 
  

  

  However, 
  even 
  the 
  thickets 
  were 
  by 
  no 
  means 
  more 
  productive 
  of 
  result 
  than 
  the 
  

   granite 
  rocks. 
  Single 
  great 
  boulders 
  standing 
  out 
  from 
  the 
  base 
  of 
  a 
  kopje 
  would 
  

   often 
  be 
  found 
  to 
  shelter 
  puparia 
  if 
  they 
  had 
  even 
  a 
  slightly 
  over-leaning 
  side, 
  and 
  

   in 
  dark 
  places 
  between 
  cleft 
  rocks, 
  or 
  under 
  rocks 
  strongly 
  shelving, 
  the 
  puparia 
  

   were 
  sometimes 
  most 
  numerous, 
  in 
  sand 
  or 
  vegetable 
  debris 
  (PI. 
  xvi, 
  fig. 
  2). 
  

  

  In 
  one 
  place 
  they 
  were 
  found 
  in 
  numbers 
  where 
  this 
  layer 
  was 
  a 
  mere 
  half-inch 
  

   thick 
  on 
  the 
  surface 
  of 
  an 
  underlying 
  rock. 
  In 
  another, 
  what 
  amounted 
  to 
  a 
  cave 
  

   sheltered 
  both 
  puparia 
  and 
  numerous 
  Argasid 
  ticks 
  (Oruithodorus) 
  , 
  though 
  villages 
  

   which 
  had 
  been 
  near 
  had 
  been 
  abandoned 
  some 
  years 
  before. 
  Under 
  single 
  rocks 
  

   near 
  Ngasamo 
  as 
  many 
  as 
  300 
  and 
  400 
  puparia 
  were 
  taken. 
  The 
  conditions 
  were 
  

   always 
  dry, 
  and 
  in 
  some 
  cases 
  ant-lion 
  pits 
  were 
  present 
  also. 
  In 
  the 
  case 
  of 
  the 
  log 
  

   shown 
  in 
  PI. 
  xvii, 
  fig. 
  2, 
  no 
  shade 
  at 
  all 
  was 
  present. 
  This 
  I 
  have 
  found 
  to 
  be 
  not 
  

   infrequent 
  in 
  the 
  case 
  of 
  G. 
  morsitans. 
  Puparia 
  were 
  also 
  taken 
  immediately 
  

   round 
  individual 
  sleeping-sickness 
  villages. 
  

  

  