﻿TSETSE 
  FLY 
  IN 
  SOUTHERN 
  RHODESIA, 
  1918. 
  81 
  

  

  particular 
  spot 
  with 
  its 
  prevalence 
  in 
  November 
  is 
  August, 
  between 
  which 
  month 
  

   and 
  the 
  past 
  wet 
  season 
  the 
  cold 
  months 
  of 
  May, 
  June 
  and 
  July 
  have 
  intervened, 
  

   we 
  are 
  in 
  a 
  similiar 
  position 
  with 
  regard 
  to 
  judging 
  whether 
  the 
  fly 
  loses 
  ground 
  in 
  

   the 
  wet 
  season 
  or 
  not, 
  as 
  in 
  estimating 
  the 
  comparative 
  breeding 
  rates. 
  Although 
  

   the 
  connection 
  may 
  not 
  be 
  apparent, 
  such 
  facts 
  might 
  well 
  shed 
  some 
  light 
  on 
  the 
  

   question 
  of 
  the 
  dependence 
  of 
  G. 
  morsitans 
  on 
  the 
  larger 
  fauna 
  of 
  the 
  forest. 
  The 
  

   matter 
  will 
  be 
  referred 
  to 
  again 
  under 
  its 
  own 
  heading. 
  

  

  Transmission 
  of 
  T. 
  pecorum 
  in 
  the 
  Absence 
  of 
  Tsetse. 
  

  

  In 
  spite 
  of 
  the 
  fact 
  that 
  direct 
  experimental 
  proof 
  is 
  still 
  apparently 
  lacking, 
  

   evidence 
  indicating 
  that 
  Trypanosoma 
  pecorum 
  is 
  commonly 
  spread 
  amongst 
  asso- 
  

   ciated 
  animals 
  in 
  the 
  absence 
  of 
  Glossina 
  has 
  accumulated 
  in 
  different 
  parts 
  of 
  

   Africa 
  during 
  recent 
  years 
  to 
  such 
  an 
  extent 
  that 
  the 
  fact 
  appears 
  now 
  to 
  be 
  

   widely 
  accepted. 
  (Bull. 
  Ent. 
  Res., 
  viii, 
  pp. 
  35-41.) 
  In 
  any 
  division 
  of 
  the 
  

   continent 
  where 
  fly 
  belts 
  occur 
  this 
  danger 
  must 
  necessarily 
  be 
  of 
  considerable 
  im- 
  

   portance, 
  and 
  not 
  least 
  in 
  Southern 
  Rhodesia 
  with 
  its 
  comparatively 
  large 
  European 
  

   population. 
  Not 
  only 
  is 
  there 
  conclusive 
  evidence 
  with 
  regard 
  to 
  this 
  form 
  of 
  trans- 
  

   mission 
  in 
  the 
  territory, 
  but 
  fresh 
  instances 
  demonstrating 
  its 
  practical 
  importance 
  

   occur 
  almost 
  every 
  season. 
  If 
  all 
  cattle 
  owners 
  within 
  measurable 
  distance 
  of 
  the 
  

   fly 
  areas 
  were 
  aware 
  of 
  the 
  danger 
  of 
  allowing 
  cattle 
  which 
  have 
  been 
  exposed 
  to 
  

   fly 
  to 
  mingle 
  with 
  healthy 
  cattle, 
  it 
  is 
  apparent 
  that 
  the 
  losses 
  from 
  trypanosomiasis 
  

   in 
  the 
  territory 
  would 
  be 
  materially 
  reduced. 
  Unfortunately, 
  transport 
  riders 
  and 
  

   others 
  who 
  are 
  most 
  likely 
  to 
  penetrate 
  fly 
  country 
  with 
  their 
  waggons 
  are 
  not 
  easily 
  

   reached 
  through 
  the 
  usual 
  mediums 
  of 
  publication. 
  

  

  It 
  may 
  be 
  pointed 
  out 
  that 
  considerable 
  confusion 
  concerning 
  the 
  occurrence 
  of 
  

   tsetse 
  in 
  various 
  parts, 
  particularly 
  in 
  the 
  Hartley 
  district, 
  has 
  been 
  occasioned 
  by 
  

   the 
  spread 
  of 
  "fly 
  disease 
  " 
  amongst 
  animals 
  which 
  have 
  never 
  been 
  in 
  a 
  known 
  

   fly 
  belt, 
  and 
  that 
  in 
  drawing 
  conclusions 
  as 
  to 
  the 
  former 
  extent 
  and 
  abundance 
  

   of 
  tsetse 
  in 
  this 
  district 
  the 
  possible 
  role 
  of 
  other 
  vectors 
  must 
  not 
  be 
  ignored. 
  

  

  Relation 
  between 
  G. 
  morsitans 
  and 
  Big 
  Game. 
  

  

  Whilst 
  it 
  is 
  obvious 
  that 
  there 
  are 
  still 
  considerable 
  grounds 
  for 
  a 
  contrary 
  

   opinion, 
  accumulated 
  evidence 
  in 
  Southern 
  Rhodesia 
  constitutes 
  a 
  case 
  for 
  a 
  vital 
  

   association 
  between 
  G. 
  morsitans 
  and 
  the 
  larger 
  fauna 
  of 
  the 
  forest, 
  which 
  it 
  is 
  

   impossible 
  to 
  ignore. 
  As 
  already 
  stated, 
  it 
  is 
  possible 
  that 
  baboons 
  play 
  a 
  more 
  

   important 
  part 
  in 
  some 
  areas 
  than 
  was 
  previously 
  recognised. 
  

  

  The 
  weakness 
  of 
  the 
  contrary 
  theory 
  appears 
  to 
  the 
  writer 
  to 
  lie 
  in 
  the 
  fact 
  that 
  no 
  

   alternative 
  explanation 
  has 
  been 
  forthcoming 
  of 
  the 
  extremely 
  striking 
  phenomena 
  

   that 
  support 
  the 
  assumption 
  of 
  a 
  vital 
  association 
  between 
  the 
  two 
  forms 
  of 
  life, 
  

   at 
  least 
  in 
  South 
  Africa. 
  It 
  is 
  not 
  the 
  writer's 
  intention 
  to 
  detail 
  the 
  arguments 
  in 
  

   favour 
  of 
  the 
  theory, 
  as 
  these 
  have 
  already 
  been 
  dealt 
  with 
  in 
  a 
  previous 
  paper, 
  

   but 
  it 
  may 
  be 
  as 
  well 
  to 
  consider 
  such 
  facts 
  as 
  have 
  been 
  made 
  public 
  which 
  weigh 
  

   on 
  the 
  other 
  side. 
  That 
  there 
  are 
  difficulties 
  in 
  accommodating 
  all 
  the 
  known 
  facts 
  

   is 
  freely 
  admitted, 
  but 
  these, 
  surely, 
  sink 
  into 
  insignificance 
  in 
  comparison 
  with 
  the 
  

   difficulties 
  of 
  explaining 
  a 
  vast 
  amount 
  of 
  evidence 
  on 
  any 
  other 
  basis. 
  It 
  is 
  possibly 
  

   true 
  that 
  G. 
  morsitans 
  is 
  not 
  everywhere 
  dependent 
  upon 
  big 
  game, 
  in 
  the 
  restricted 
  

   sense, 
  but 
  that 
  the 
  fly 
  is 
  and 
  has 
  been 
  dependent 
  upon 
  the 
  larger 
  mammals 
  through- 
  

   out 
  the 
  greater 
  portion 
  of 
  its 
  range 
  in 
  South 
  Africa 
  is 
  more 
  than 
  probable. 
  

   (C572) 
  p 
  

  

  