﻿ENTOMOLOGICAL 
  ASPECTS 
  OF 
  AN 
  OUTBREAK 
  OF 
  SLEEPING 
  SICKNESS. 
  331 
  

  

  Water-holes 
  and 
  Swamps. 
  — 
  On 
  three 
  occasions 
  in 
  the 
  Simiyu 
  area, 
  working 
  with 
  

   the 
  cattle, 
  I 
  sustained 
  considerable 
  attacks 
  on 
  arriving 
  at 
  water-holes. 
  Two 
  of 
  

   these 
  were 
  beside 
  bushy 
  granite 
  kopjes, 
  but 
  themselves 
  in 
  lightly 
  infested 
  bush 
  (in 
  

   one 
  case 
  mere 
  brakes 
  of 
  a 
  shrubby 
  Combretum), 
  and 
  the 
  third 
  has 
  just 
  been 
  described. 
  

   In 
  general, 
  we 
  seemed 
  able 
  to 
  count 
  on 
  an 
  attack, 
  large 
  or 
  small, 
  on 
  reaching 
  a 
  water- 
  

   hole 
  (as 
  opposed 
  to 
  a 
  pool 
  in 
  a 
  stream). 
  

  

  The 
  edges 
  of 
  open 
  swamps 
  bordered 
  by 
  numerous 
  ilula 
  acacias, 
  and 
  for 
  the 
  most 
  

   part 
  now 
  dry, 
  were 
  sometimes 
  points 
  of 
  attack 
  by 
  several 
  flies 
  together, 
  or 
  (if 
  we 
  

   stood) 
  a 
  succession 
  of 
  them. 
  Such 
  points 
  were 
  regarded 
  as 
  bad 
  by 
  the 
  natives, 
  who 
  

   said 
  of 
  the 
  seasonal 
  connection 
  between 
  the 
  fly 
  and 
  the 
  ilula 
  (and 
  mkwata), 
  " 
  The 
  

   fly 
  never 
  leaves 
  them." 
  I 
  failed 
  to 
  find 
  at 
  these 
  places 
  the 
  visible 
  fly-concentrations 
  

   on 
  grass 
  and 
  paths 
  that 
  I 
  found 
  in 
  the 
  case 
  of 
  typical 
  morsilans 
  in 
  similar 
  situations 
  

   in 
  Portuguese 
  East 
  Africa 
  — 
  though 
  Turnbull 
  one 
  day 
  sustained 
  an 
  extraordinarily 
  

   heavy 
  attack 
  at 
  a 
  spot 
  in 
  a 
  small 
  open 
  vlei 
  near 
  kopjes 
  in 
  which 
  I 
  failed 
  to 
  obtain 
  

   any 
  tsetse 
  on 
  a 
  subsequent 
  special 
  visit 
  — 
  but 
  they 
  were 
  definitely 
  regarded 
  by 
  the 
  

   natives 
  as 
  bad. 
  The 
  same, 
  it 
  may 
  be 
  added, 
  applies 
  to 
  G. 
  morsitans. 
  Vleis 
  lined 
  

   with 
  ilula 
  that 
  Major 
  Murray 
  and 
  myself 
  had 
  traversed 
  in 
  motoring 
  from 
  Tabora 
  to 
  

   Kahama 
  had 
  provided 
  fairly 
  heavy 
  onslaughts 
  by 
  the 
  latter 
  fly. 
  This 
  was 
  on 
  

   3rd 
  May, 
  when 
  the 
  surrounding 
  bush 
  was 
  still 
  full 
  of 
  leaf. 
  

  

  When 
  thickets 
  such 
  as 
  I 
  have 
  described 
  as 
  of 
  the 
  pallidipes 
  type 
  bounded 
  a 
  swamp, 
  

   the 
  presence 
  of 
  more 
  or 
  less 
  numerous 
  tsetse 
  (G. 
  swynnertoni) 
  was 
  nearly 
  certain. 
  

   Such 
  a 
  spot, 
  where 
  there 
  was 
  a 
  severe 
  onslaught 
  by 
  tsetses, 
  is 
  shown 
  in 
  fig. 
  2 
  of 
  

   Plate 
  xiii. 
  

  

  Rivers. 
  — 
  It 
  is 
  curious 
  that 
  in 
  the 
  infected 
  area 
  we 
  failed 
  to 
  take 
  this 
  fly 
  at 
  all 
  

   definitely 
  in 
  any 
  of 
  the 
  formations 
  which 
  I 
  have 
  described 
  above 
  as 
  " 
  fringing." 
  

   These 
  were 
  very 
  thoroughly 
  searched 
  where 
  found 
  in 
  order 
  to 
  make 
  sure 
  of 
  the 
  presence 
  

   or 
  absence 
  of 
  palpalis, 
  brevipalpis, 
  or 
  anstcni. 
  The 
  incriminated 
  fly 
  was 
  not 
  even 
  

   taken 
  in 
  the 
  more 
  open 
  mgu 
  acacia 
  formation 
  prominent 
  on 
  the 
  Duma 
  and 
  lower 
  

   Simiyu, 
  except 
  as 
  individuals 
  that 
  had 
  followed 
  us 
  in, 
  yet 
  was 
  present 
  in 
  some 
  

   numbers 
  just 
  outside. 
  Pangonia, 
  on 
  the 
  other 
  hand, 
  was 
  particularly 
  abundant 
  

   in 
  such 
  places. 
  

  

  It 
  is 
  likely 
  enough 
  that 
  the 
  dry 
  season 
  and 
  the 
  fires 
  may 
  drive 
  the 
  fly 
  to 
  the 
  very 
  

   spots 
  from 
  which 
  we 
  found 
  it 
  to 
  be 
  nearly 
  absent 
  — 
  these 
  fringing 
  formations 
  and 
  

   the 
  kopjes. 
  Dr. 
  Maclean 
  found 
  on 
  12th 
  June 
  many 
  more 
  flies 
  on 
  the 
  streams 
  in 
  

   Msanza 
  Mdogo 
  than 
  between 
  them, 
  and 
  this 
  may 
  have 
  been 
  the 
  beginning 
  of 
  a 
  

   concentration. 
  Manangwa 
  Masalu, 
  a 
  headman 
  who 
  accompanied 
  me 
  northwards 
  

   from 
  Nasa 
  to 
  Kalemera 
  in 
  Msanza 
  Mdogo, 
  informed 
  me 
  that 
  the 
  bush 
  on 
  the 
  small 
  

   dry 
  streams 
  we 
  crossed 
  here 
  was 
  also, 
  a 
  little 
  later, 
  a 
  concentrating-place 
  for 
  this 
  

   tsetse. 
  It 
  was 
  composed 
  of 
  Acacia 
  spirocarpa, 
  some 
  Albizzia 
  brachycalyx, 
  some 
  

   tamarinds 
  and 
  dense 
  thicket 
  of 
  Grewia 
  and 
  other 
  genera. 
  

  

  Fly 
  was 
  taken 
  also 
  at 
  the 
  Mbarangeti 
  and 
  Rowana 
  fords 
  — 
  that 
  is, 
  in 
  secondary 
  

   fringing 
  forest 
  sandwiched 
  between 
  great 
  open 
  mbugas 
  — 
  by 
  both 
  parties 
  which 
  

   preceded 
  me, 
  each 
  travelling 
  by 
  the 
  main 
  road. 
  My 
  personal 
  party, 
  which 
  met 
  

   the 
  Mbarangeti 
  lower 
  and 
  followed 
  the 
  Rowana 
  up 
  from 
  its 
  mouth, 
  searching 
  it 
  slowly 
  

   and 
  carefully 
  and 
  taking 
  numerous 
  brevipalpis, 
  but 
  striking 
  off 
  before 
  reaching 
  the 
  

   main 
  road, 
  found 
  none. 
  This 
  difference 
  in 
  result 
  was 
  explained, 
  I 
  am 
  inclined 
  to 
  

   think, 
  by 
  a 
  previous 
  observation 
  on 
  the 
  little 
  Gudama 
  stream. 
  

  

  IX. 
  — 
  An 
  Apparent 
  Method 
  of 
  Concentration. 
  

  

  In 
  the 
  observation 
  just 
  referred 
  to, 
  on 
  the 
  Gudama, 
  Turnbull 
  and 
  I 
  took 
  several 
  

   flies 
  in 
  a 
  stream-bed 
  thicket 
  at 
  a 
  ford, 
  yet 
  I 
  could 
  find 
  none 
  in 
  similar 
  thickets 
  in 
  the 
  

   same 
  stream 
  bed 
  anywhere 
  away 
  from 
  the 
  ford, 
  in 
  spite 
  of 
  stays 
  of 
  half 
  an 
  hour 
  in 
  

   each 
  place 
  tested. 
  In 
  this 
  instance, 
  at 
  the 
  ford, 
  we 
  first 
  took 
  five 
  females 
  fairly 
  

  

  