﻿INVESTIGATIONS 
  INTO 
  THE 
  BIONOMICS 
  OF 
  GLOSSINA 
  PALPALIS. 
  427 
  

  

  proportionately, 
  of 
  hatched 
  shells 
  to 
  whole 
  puparia 
  (see 
  Table 
  XXVIII, 
  p. 
  414) 
  as 
  

   to 
  prove 
  that 
  a 
  more 
  dense 
  infestation 
  had 
  recently 
  existed 
  ; 
  and 
  reduction 
  in 
  density 
  

   was 
  explicable 
  because 
  of 
  the 
  fact 
  that 
  this 
  particular 
  spot 
  also 
  bore 
  evidence 
  of 
  

   having 
  been 
  recently 
  abandoned 
  as 
  a 
  basking 
  ground 
  by 
  Varanus. 
  A 
  similar 
  

   instance 
  was 
  encountered 
  on 
  Karambidi, 
  where 
  in 
  what 
  plainly 
  had 
  been 
  until 
  very 
  

   recently 
  the 
  basking 
  spot 
  of 
  Varanus 
  had 
  also 
  been 
  a 
  favoured 
  breeding 
  spot 
  of 
  tsetse,, 
  

   which 
  had 
  been 
  very 
  recently 
  abandoned, 
  as 
  proved 
  in 
  this 
  case 
  by 
  the 
  most 
  excep- 
  

   tional 
  proportion 
  of 
  puparia 
  in 
  a 
  late 
  stage 
  of 
  development. 
  

  

  Of 
  most 
  particular 
  interest 
  in 
  this 
  connection 
  are 
  the 
  circumstances 
  surrounding 
  

   the 
  occurrence 
  of 
  an 
  island 
  colony 
  of 
  tsetse, 
  breeding 
  exclusively 
  in 
  vegetable 
  debris 
  

   on 
  the 
  very 
  crest 
  of 
  a 
  heavily 
  forested 
  hill. 
  In 
  this 
  case, 
  cited 
  more 
  at 
  length 
  in 
  

   Sect. 
  V 
  (d), 
  isolation 
  was 
  produced 
  by 
  the 
  forest, 
  which 
  is, 
  like 
  open 
  water, 
  an 
  

   obstruction 
  to 
  dispersion 
  without 
  being 
  an 
  insuperable 
  obstacle 
  to 
  it. 
  

  

  It 
  can 
  safely 
  be 
  predicted 
  that 
  if 
  any 
  long 
  reach 
  of 
  shore 
  which 
  provides 
  good 
  

   shelter 
  and 
  plenty 
  of 
  food 
  is 
  found 
  with 
  breeding 
  places 
  in 
  vegetable 
  debris 
  at 
  

   sufficiently 
  frequent 
  intervals, 
  it 
  will 
  be 
  found 
  infested 
  by 
  fly 
  ; 
  for 
  then 
  flies 
  dispersing 
  

   from 
  one 
  would 
  find 
  another. 
  But 
  such 
  conditions 
  had 
  not 
  been 
  found 
  at 
  the 
  close 
  

   of 
  these 
  investigations. 
  

  

  VIII. 
  The 
  Shelter 
  Required 
  by 
  Glossina 
  Palpalis. 
  

  

  Two 
  points 
  in 
  the 
  bionomics 
  of 
  Glossina 
  palpalis 
  are 
  so 
  conspicuous 
  as 
  to 
  be 
  noted 
  

   by 
  every 
  observer 
  : 
  its 
  riparian 
  habit, 
  and 
  its 
  dependence 
  on 
  the 
  shelter 
  provided 
  

   by 
  arborescent 
  or 
  rankly-growing 
  herbaceous 
  vegetation. 
  It 
  is 
  rarely 
  found 
  far 
  from 
  

   open 
  water 
  and 
  never 
  far 
  from 
  sheltering 
  vegetation. 
  

  

  The 
  effect 
  of 
  water 
  upon 
  range 
  and 
  density 
  of 
  the 
  species 
  appears 
  to 
  be 
  indirect 
  

   and 
  coincidental, 
  as 
  concluded 
  in 
  Sect. 
  IV 
  ; 
  that 
  of 
  shelter 
  is 
  certainly 
  not 
  so. 
  The 
  

   flies 
  absolutely 
  require 
  the 
  kind 
  of 
  protection 
  it 
  affords 
  them, 
  and 
  the 
  species 
  could 
  

   not 
  exist 
  in 
  the 
  absence 
  of 
  it. 
  

  

  It 
  was 
  not 
  expected 
  that 
  these 
  studies 
  would 
  lead 
  to 
  any 
  new 
  discoveries 
  concerning 
  

   the 
  specific 
  types 
  of 
  sheltering 
  vegetation 
  that 
  provide 
  necessary 
  protection, 
  but 
  

   it 
  was 
  taken 
  too 
  much 
  for 
  granted 
  that 
  where 
  the 
  flies 
  were 
  found 
  in 
  largest 
  numbers 
  

   the 
  shelter 
  would 
  be, 
  at 
  least, 
  adequate. 
  This 
  proved 
  not 
  so 
  ; 
  and 
  it 
  was 
  discovered 
  

   that 
  the 
  shelter 
  most 
  attractive 
  to 
  the 
  active 
  flies, 
  or 
  that 
  serves 
  best 
  to 
  shade 
  breeding 
  

   grounds 
  and 
  as 
  protection 
  for 
  the 
  puparia, 
  is 
  frequently 
  inadequate 
  as 
  protection 
  

   for 
  the 
  inactive 
  flies. 
  Two 
  kinds 
  of 
  shelter 
  are 
  requisite, 
  (a) 
  light, 
  such 
  as 
  serves 
  

   at 
  breeding 
  grounds 
  and 
  for 
  the 
  active 
  flies 
  ; 
  and 
  (b) 
  massive, 
  or 
  forest-like, 
  which 
  

   is 
  required 
  by 
  the 
  inactive 
  flies. 
  

  

  In 
  no 
  other 
  manner 
  was 
  it 
  possible 
  to 
  explain 
  the 
  distribution 
  of 
  fly 
  on 
  the 
  islands, 
  

   as 
  disclosed 
  by 
  the 
  island 
  survey. 
  The 
  idea 
  was 
  made 
  a 
  working 
  hypothesis, 
  and 
  

   subsequent 
  survey 
  work 
  sufficiently 
  confirmed 
  it, 
  as 
  recounted 
  in 
  the 
  following 
  pages. 
  

  

  VIII 
  (a). 
  Correlation 
  between 
  Character 
  of 
  Shelter 
  and 
  Infestation 
  of 
  small 
  

   Islands 
  by 
  Fly. 
  

  

  Reference 
  to 
  Table 
  XXXII 
  will 
  show 
  that 
  though 
  on 
  certain 
  small 
  islands, 
  notably 
  

   Lukalu 
  East 
  and 
  Kukassu, 
  infestation 
  was 
  nil 
  despite 
  the 
  presence 
  of 
  " 
  very 
  good 
  " 
  

  

  (659) 
  f 
  

  

  