﻿INVESTIGATIONS 
  INTO 
  THE 
  BIONOMICS 
  OP 
  GLOSSINA 
  PALPALIS. 
  

  

  401 
  

  

  YI 
  (c). 
  Experiments 
  with 
  Animals 
  under 
  Constraint 
  to 
  determine 
  Host 
  

   Preferences 
  of 
  Glossina 
  palpalis. 
  

  

  1. 
  Comparison 
  between 
  Goat, 
  Pig, 
  Varanus 
  and 
  Man. 
  

  

  This 
  experiment 
  was 
  made 
  on 
  Lugazi 
  Island 
  in 
  December 
  1913. 
  Mention 
  has 
  

   already 
  been 
  made 
  of 
  it 
  (Sect. 
  II 
  (b) 
  ). 
  The 
  animals 
  were 
  exposed 
  as 
  equally 
  as 
  possible 
  

   along 
  a 
  bit 
  of 
  beach. 
  The 
  goats 
  were 
  native 
  stock 
  and 
  full-grown 
  ; 
  the 
  pigs 
  of 
  

   European 
  stock 
  and 
  only 
  about 
  one-quarter 
  grown 
  ; 
  the 
  Varanus 
  were 
  newly 
  caught, 
  

   one 
  being 
  full-grown 
  and 
  the 
  other 
  about 
  half. 
  

  

  The 
  bites 
  inflicted 
  upon 
  man 
  were 
  counted 
  for 
  comparative 
  purposes, 
  but 
  the 
  

   comparison 
  is 
  not 
  exact, 
  because 
  only 
  the 
  flies 
  actually 
  engorging 
  on 
  the 
  animals 
  

   were 
  counted, 
  and 
  some 
  bit 
  without 
  engorging. 
  The 
  goats 
  appeared 
  to 
  have 
  been 
  

   bitten 
  several 
  times, 
  and 
  each 
  time 
  prevented 
  the 
  fly 
  from 
  feeding. 
  The 
  complete 
  

   immunity 
  of 
  goats 
  and 
  man, 
  in 
  so 
  far 
  as 
  engorgement 
  is 
  concerned, 
  is 
  due 
  to 
  the 
  same 
  

   cause 
  — 
  an 
  instinctive 
  movement 
  in 
  self-protection 
  which 
  causes 
  the 
  fly 
  to 
  desist 
  

   from 
  attack. 
  Neither 
  were 
  immune 
  from 
  being 
  bitten, 
  and 
  bites 
  on 
  goats 
  were 
  

   probably 
  about 
  as 
  numerous 
  as 
  on 
  man. 
  

  

  Table 
  XXII. 
  

  

  The 
  Relative 
  Attractiveness 
  of 
  Varanus, 
  Goat, 
  Pig 
  and 
  Man 
  to 
  Glossina 
  palpalis. 
  

  

  Host. 
  

  

  No. 
  of 
  hours 
  exposed 
  

  

  No. 
  of 
  bites 
  inflicted. 
  

  

  No, 
  of 
  bites 
  per 
  hour. 
  

  

  Varanus 
  

  

  Pig 
  

  

  Goat 
  

  

  Man, 
  African 
  . 
  . 
  

   ,, 
  European 
  

  

  24 
  

  

  32i 
  

  

  76 
  

   38 
  

  

  202 
  

  

  60 
  

   1 
  

   

   1 
  

   5 
  

  

  2-50 
  

   •03 
  

   "00 
  

   •03 
  

  

  •02 
  

  

  Infestation 
  by 
  fly 
  at 
  the 
  point 
  where 
  the 
  experiment 
  was 
  made 
  was 
  : 
  — 
  Male 
  density 
  

   6*0 
  ; 
  female 
  percentage 
  15*5. 
  

  

  The 
  strong 
  preference 
  displayed 
  by 
  fly 
  for 
  Varanus 
  over 
  the 
  other 
  hosts 
  was 
  

   confirmed 
  in 
  subsequent 
  experiments. 
  The 
  results 
  with 
  pig 
  proved 
  untrustworthy. 
  

   It 
  was 
  later 
  discovered 
  (p. 
  381) 
  that 
  this 
  animal 
  is 
  sometimes, 
  at 
  least, 
  a 
  favoured 
  

   host. 
  

  

  2. 
  Comparison 
  between 
  Goat, 
  Varanus 
  and 
  Crocodile. 
  

  

  Two 
  goats, 
  one 
  Varanus 
  and 
  one 
  crocodile 
  were 
  used 
  in 
  a 
  short 
  experiment 
  on 
  

   Kimmi 
  Island 
  on 
  the 
  27th 
  January 
  1914. 
  The 
  crocodile 
  was 
  young 
  and 
  active, 
  

   and 
  between 
  3 
  and 
  4 
  feet 
  in 
  length. 
  The 
  Varanus 
  was 
  slightly 
  larger. 
  All 
  animals 
  

   were 
  exposed 
  as 
  equally 
  as 
  possible. 
  The 
  crocodile 
  first, 
  and 
  soon 
  after 
  the 
  Varanus, 
  

   became 
  intractable, 
  apparently 
  because 
  of 
  the 
  swarms 
  of 
  flies 
  which 
  assailed 
  them, 
  

   and 
  the 
  experiment 
  had 
  to 
  be 
  discontinued. 
  

  

  The 
  infestation 
  of 
  this 
  island 
  at 
  this 
  time 
  was 
  : 
  — 
  Male 
  density 
  24*3 
  ; 
  female 
  

  

  percentage 
  57*5. 
  

  

  