﻿INVESTIGATIONS 
  INTO 
  THE 
  BIONOMICS 
  OF 
  GLOSSINA 
  PALPALIS. 
  

  

  367 
  

  

  before 
  the 
  experiment 
  was 
  repeated. 
  In 
  other 
  words, 
  if 
  catching 
  is 
  continued 
  over 
  

   several 
  consecutive 
  hours, 
  the 
  density 
  of 
  male 
  flies, 
  but 
  not 
  of 
  active 
  females, 
  will 
  

   be 
  reduced 
  during 
  the 
  first 
  hour, 
  and 
  will 
  not 
  rise 
  again 
  to 
  normal 
  until 
  several 
  hours 
  

   have 
  elapsed. 
  

  

  Table 
  XIII. 
  

  

  Catches 
  of 
  Fly 
  for 
  consecutive 
  hours 
  at 
  points 
  on 
  Lake 
  Shore, 
  showing 
  Reduction 
  

   in 
  Density 
  of 
  Males 
  but 
  not 
  of 
  Active 
  Females, 
  and 
  demonstrating 
  more 
  rapid 
  

  

  movement 
  of 
  Females. 
  

  

  Locality. 
  

  

  Date. 
  

  

  Hour. 
  

  

  Catch 
  of 
  Fly. 
  

  

  Total. 
  

  

  Females. 
  

  

  Density 
  of 
  Active 
  Fly. 
  

  

  Males. 
  

  

  Females. 
  

  

  Total. 
  

  

  Crocodile 
  Point, 
  

   Bulago 
  Island 
  

  

  Landing 
  Place. 
  

   Tavu 
  Island 
  . 
  

  

  fl7th 
  Jan. 
  

   \ 
  1914 
  .. 
  

  

  /15th 
  Jan. 
  

   \ 
  1914 
  . 
  . 
  

  

  1st 
  

  

  343 
  

  

  2nd 
  

  

  319 
  

  

  3rd 
  

  

  250 
  

  

  1st 
  

  

  419 
  

  

  2nd 
  

  

  250 
  

  

  3rd 
  

  

  183 
  

  

  4th 
  

  

  163 
  

  

  5th 
  

  

  167 
  

  

  30-9 
  % 
  

   41-4 
  °/ 
  

  

  2 
  

   7 
  

   4 
  

  

  3 
  

  

  2 
  

  

  56 
  

   10 
  

   10 
  

   21 
  

  

  25 
  

  

  26-8 
  

  

  o 
  

  

  /o 
  

   /o 
  

   /o 
  

  

  /o 
  

  

  °L 
  

   /o 
  

  

  /o 
  

  

  35-0 
  

  

  141 
  

  

  26-7 
  

  

  18-5 
  

  

  145 
  

  

  18-7 
  

  

  62-3 
  

  

  7-5 
  

  

  37-4 
  

  

  43 
  

  

  24-0 
  

  

  6-5 
  

  

  20-3 
  

  

  6-8 
  

  

  20-3 
  

  

  7-5 
  

  

  49-1 
  

   45'2 
  

   33-2 
  

  

  698 
  

   41-7 
  

   30-5 
  

   27-1 
  

  

  27-8 
  

  

  These 
  experiments 
  were 
  many 
  times 
  repeated 
  with 
  results 
  similar 
  to 
  those 
  presented 
  

   in 
  Table 
  XIII. 
  It 
  was 
  found 
  that 
  the 
  local 
  density 
  of 
  male 
  flies 
  could 
  be 
  very 
  quickly 
  

   and 
  easily 
  reduced, 
  whereas 
  that 
  of 
  active 
  females 
  was 
  not 
  affected 
  in 
  this 
  manner. 
  

   It 
  was 
  conclusively 
  proved 
  by 
  experiments 
  cited 
  on 
  p. 
  365, 
  and 
  illustrated 
  by 
  

   Table 
  XII, 
  that 
  reduction 
  in 
  density 
  of 
  males 
  would 
  be 
  made 
  good 
  by 
  incoming 
  

   flies 
  if 
  some 
  hours 
  were 
  allowed 
  to 
  elapse 
  before 
  a 
  second 
  catch 
  was 
  made, 
  but 
  that 
  

   no 
  period 
  of 
  waiting 
  was 
  required 
  to 
  make 
  good 
  any 
  reduction 
  in 
  density 
  of 
  active 
  

   females 
  caused 
  by 
  catching. 
  

  

  The 
  only 
  conclusion 
  that 
  can 
  be 
  drawn 
  is 
  that 
  the 
  active 
  females 
  habitually 
  move 
  

   along 
  shore 
  much 
  more 
  rapidly 
  than 
  the 
  males, 
  or 
  than 
  many 
  of 
  the 
  males. 
  This 
  

   is 
  entirely 
  in 
  accord 
  with 
  the 
  conclusions 
  reached 
  through 
  experiments 
  cited 
  in 
  Sect. 
  I, 
  

   that 
  active 
  females 
  are 
  hungry, 
  and 
  actively 
  seeking 
  food, 
  and 
  that 
  degree 
  of 
  activity 
  

   is 
  correlated 
  with 
  abundance 
  or 
  scarcity 
  of 
  food. 
  Their 
  movements 
  along 
  shore 
  

   are 
  stimulated 
  by 
  hunger. 
  The 
  movements 
  of 
  the 
  males 
  are 
  in 
  part 
  stimulated 
  by 
  

   hunger, 
  but 
  also 
  in 
  part 
  (see 
  Sect. 
  IV) 
  by 
  sex 
  instinct. 
  The 
  object 
  of 
  the 
  females 
  — 
  ■ 
  

   and 
  of 
  such 
  males 
  as 
  require 
  it 
  — 
  is 
  to 
  seek 
  food 
  ; 
  the 
  object 
  of 
  many 
  of 
  the 
  males 
  

   (forming 
  a 
  majority 
  when 
  females 
  are 
  inactive 
  and 
  the 
  female 
  percentage 
  low) 
  is 
  

   merely 
  to 
  seek 
  the 
  females, 
  and 
  this 
  is 
  accomplished 
  by 
  loitering 
  along 
  the 
  routes 
  

   most 
  freely 
  followed 
  by 
  the 
  food-hunting 
  flies. 
  

  

  This 
  conclusion 
  found 
  ample 
  confirmation 
  as 
  the 
  investigations 
  progressed 
  ; 
  as, 
  

   for 
  example, 
  by 
  the 
  fact 
  that 
  when 
  food 
  is 
  so 
  scanty 
  on 
  an 
  island 
  (as 
  on 
  Kimmi 
  

   Island 
  in 
  January 
  1914) 
  that 
  the 
  female 
  percentage 
  is 
  very 
  high, 
  it 
  is 
  impossible 
  

   to 
  reduce 
  the 
  local 
  density 
  of 
  either 
  males 
  or 
  females 
  by 
  catching 
  experiments 
  at 
  

  

  