﻿REPORT 
  OF 
  TSETSE-FLY 
  INVESTIGATION 
  IN 
  NIGERIA. 
  375 
  

  

  Torrents 
  such 
  as 
  those 
  described 
  are 
  common 
  in 
  the 
  hilly 
  country 
  from 
  Kaduna 
  to 
  

   Benue 
  Bridge, 
  and 
  palpalis 
  was 
  found 
  upon 
  all 
  these. 
  Similar 
  torrents, 
  palpalis- 
  

   infested, 
  were 
  met 
  with 
  around 
  the 
  north 
  base 
  of 
  the 
  Bauchi 
  Plateau, 
  on 
  tributaries 
  

   of 
  the 
  Bunga 
  River, 
  which 
  is 
  a 
  feeder 
  of 
  Lake 
  Chad, 
  in 
  seven 
  instances 
  alone 
  and 
  

   in 
  one, 
  where 
  the 
  river-bed 
  was 
  less 
  ravine-like, 
  in 
  company 
  with 
  tachinoides. 
  This 
  

   species 
  is 
  similarly 
  found 
  without 
  tachinoides 
  on 
  the 
  torrents 
  around 
  Zungeru 
  and 
  

   from 
  this 
  place 
  up 
  to 
  Gwari. 
  East 
  of 
  this 
  point 
  the 
  country 
  flattens 
  out, 
  the 
  streams 
  

   are 
  no 
  longer 
  torrents 
  in 
  ravines, 
  palpalis 
  becomes 
  rare, 
  and 
  tachinoides 
  is 
  the 
  common 
  

   riverside 
  tsetse. 
  G. 
  palpalis 
  is 
  also 
  met 
  with 
  alone 
  in 
  the 
  rainy 
  season 
  in 
  the 
  inundated 
  

   forests 
  around 
  the 
  Niger, 
  while 
  the 
  other 
  species 
  keep 
  on, 
  or 
  close 
  to, 
  well 
  drained 
  

   ground. 
  

  

  It 
  is 
  of 
  great 
  importance 
  that 
  palpalis 
  is 
  very 
  scarce 
  in 
  excessively 
  dense 
  rain 
  

   forest, 
  since 
  this 
  allows 
  no 
  space 
  for 
  flight 
  (cf. 
  Fiske 
  (3) 
  ) 
  and 
  is 
  also 
  perhaps 
  rather 
  

   devoid 
  of 
  food. 
  A 
  broad 
  road 
  cut 
  through 
  such 
  a 
  forest 
  does 
  not 
  satisfy 
  these 
  

   requirements, 
  and, 
  so 
  far 
  as 
  we 
  have 
  seen, 
  village 
  clearings 
  in 
  the 
  heart 
  of 
  them 
  

   are 
  uninfested 
  by 
  the 
  fly 
  except 
  for 
  rare 
  stragglers. 
  

  

  The 
  change 
  in 
  the 
  character 
  of 
  the 
  country 
  from 
  that 
  which 
  is 
  suitable 
  to 
  palpalis 
  

   to 
  that 
  which 
  is 
  suitable 
  to 
  tachinoides 
  is 
  well 
  seen 
  on 
  the 
  Benue 
  River 
  in 
  a 
  journey 
  

   from 
  Benue 
  Bridge 
  to 
  Numan 
  in 
  the 
  dry 
  season. 
  From 
  Benue 
  Bridge 
  to 
  the 
  mouth 
  

   of 
  the 
  Katsina 
  River 
  there 
  is 
  almost 
  continuous 
  heavy 
  forest 
  of 
  dark 
  evergreens 
  

   with 
  the 
  larger 
  climbing 
  plants, 
  such 
  as 
  lianas 
  and 
  wine 
  palms 
  (Raphia 
  vinifera). 
  

   G. 
  palpalis 
  is 
  the 
  dominant 
  tsetse 
  in 
  these, 
  but 
  tachinoides 
  also 
  occurs. 
  From 
  Benue 
  

   Bridge 
  to 
  Abinsi 
  indiscriminate 
  catches 
  of 
  tsetse 
  contained 
  89 
  per 
  -cent, 
  palpalis 
  to 
  

   11 
  per 
  cent, 
  tachinoides 
  ; 
  from 
  the 
  latter 
  place 
  to 
  a 
  point 
  just 
  past 
  the 
  mouth 
  of 
  the 
  

   Katsina 
  River 
  similar 
  catches 
  contained 
  22 
  per 
  cent, 
  palpalis 
  and 
  78 
  per 
  cent. 
  

   tachinoides 
  ; 
  from 
  there 
  onwards 
  no 
  more 
  palpalis 
  were 
  seen, 
  though 
  individuals 
  

   have 
  occasionally 
  been 
  taken 
  here 
  and 
  there 
  since 
  the 
  tributaries 
  of 
  the 
  Benue 
  are 
  

   palpalis-haunted 
  away 
  from 
  the 
  main 
  river 
  and 
  a 
  few 
  of 
  the 
  flies 
  straggle 
  down 
  to 
  

   the 
  Benue. 
  East 
  of 
  the 
  last 
  point 
  mentioned 
  the 
  banks 
  become 
  drier 
  and 
  the 
  ever- 
  

   green 
  forest 
  is 
  more 
  patchy, 
  with 
  intervening 
  savannah 
  plains. 
  The 
  large 
  forest 
  

   trees 
  are 
  still 
  plentiful, 
  but 
  lianas 
  are 
  being 
  replaced 
  by 
  trailing 
  plants 
  (bramble 
  type), 
  

   such 
  as 
  Dichrostachys 
  platycarpa 
  (sarkakiya) 
  and 
  herbaceous 
  climbers, 
  such 
  as 
  the 
  

   " 
  wild 
  yam 
  " 
  (Vitis 
  pallida). 
  Most 
  of 
  these 
  die 
  back 
  in 
  the 
  dry 
  season, 
  and 
  the 
  

   patches 
  of 
  forest 
  contain 
  an 
  increasing 
  proportion 
  of 
  deciduous 
  trees. 
  Fierce 
  bush 
  

   fires 
  occasionally 
  pass 
  through 
  these 
  bits 
  of 
  forest, 
  consuming 
  the 
  dry 
  undergrowth. 
  

   Such 
  a 
  forest 
  is 
  shown 
  in 
  Plate 
  xix, 
  fig. 
  1, 
  a 
  spot 
  near 
  Ibi. 
  The 
  next 
  marked 
  change 
  

   in 
  the 
  flora 
  is 
  the 
  appearance 
  of 
  forests 
  of 
  fan 
  palms 
  (Borassus 
  flabellifera) 
  and 
  these 
  

   are 
  tsetse-free 
  in 
  the 
  dry 
  season. 
  Mimosa 
  occurs 
  all 
  the 
  way 
  up 
  the 
  river, 
  but 
  near 
  

   Mutum 
  Biu 
  it 
  begins 
  to 
  predominate, 
  and 
  some 
  20 
  miles 
  below 
  Lau 
  dense 
  mimosa 
  

   shrubberies 
  replace 
  the 
  forest 
  and 
  tsetse-flies 
  are 
  no 
  longer 
  found. 
  Shade 
  trees 
  are 
  

   scanty 
  and 
  isolated,* 
  and 
  this 
  condition 
  obtains 
  up 
  to 
  Numan, 
  the 
  river 
  flowing 
  

   through 
  long-grassed 
  plains 
  cut 
  up 
  by 
  mimosa-filled 
  creeks. 
  Plate 
  xix, 
  fig. 
  2, 
  shows 
  

   a 
  mimosa 
  creek 
  with 
  scanty 
  shade 
  trees 
  some 
  20 
  miles 
  below 
  Lau, 
  the 
  last 
  spot 
  on 
  

   the 
  river 
  where 
  we 
  found 
  tachinoides. 
  Above 
  Yola, 
  however, 
  the 
  vegetation 
  again 
  

   changes 
  to 
  forest 
  and 
  tsetse-flies 
  occur. 
  

  

  Throughout 
  the 
  northern 
  and 
  eastern 
  parts 
  of 
  the 
  Northern 
  Provinces 
  are 
  many 
  

   places 
  where 
  tachinoides 
  is 
  found 
  in 
  the 
  absence 
  of 
  palpalis. 
  These 
  are 
  always 
  areas 
  

   of 
  primary 
  forest, 
  often 
  of 
  very 
  small 
  extent, 
  with 
  shade 
  sufficiently 
  dense 
  to 
  prohibit 
  

   the 
  growth 
  of 
  grass 
  or 
  a 
  continuous 
  undergrowth 
  of 
  dense 
  shrubs, 
  and 
  with 
  water 
  

   on 
  or 
  very 
  near 
  the 
  surface. 
  The 
  fly 
  seems 
  to 
  require 
  open 
  spaces 
  apart 
  from 
  the 
  

   bed 
  of 
  the 
  stream 
  itself 
  and 
  this 
  is 
  probably 
  the 
  reason 
  why 
  it 
  is 
  absent 
  from 
  the 
  

  

  * 
  Isolated 
  trees 
  do 
  not 
  inhibit 
  the 
  growth 
  of 
  long 
  grass 
  — 
  a 
  condition 
  which 
  appears 
  to 
  be 
  

   unsuitable 
  for 
  the 
  fly. 
  

  

  (8455) 
  2 
  d 
  2 
  

  

  