﻿INVESTIGATIONS 
  INTO 
  THE 
  BIONOMICS 
  OF 
  GLOSSINA 
  PALPALIS. 
  419 
  

  

  Mbugwe 
  Island, 
  March 
  1915. 
  

  

  The 
  one 
  case 
  in 
  which 
  what 
  appeared 
  certainly 
  to 
  be 
  an 
  independent 
  inland 
  

   colony, 
  and 
  the 
  only 
  case 
  of 
  a 
  colony 
  independent 
  of 
  breeding 
  grounds 
  in 
  sand 
  or 
  

   gravel 
  except 
  those 
  on 
  tiny 
  islets, 
  is 
  described 
  in 
  Sect. 
  V 
  (d). 
  This 
  is 
  a 
  unique 
  and 
  

   important 
  observation. 
  

  

  VII 
  (d). 
  The 
  "Fly 
  Beaches." 
  

  

  The 
  very 
  notable 
  attractiveness 
  of 
  shaded 
  deposits 
  of 
  beach 
  sand 
  or 
  gravel 
  to 
  

   the 
  females 
  of 
  Glossina 
  palpalis, 
  coupled 
  with 
  the 
  need 
  of 
  the 
  species 
  for 
  protection 
  

   during 
  the 
  pupal 
  stages 
  and 
  the 
  high 
  degree 
  of 
  protection 
  provided 
  by 
  the 
  most 
  

   attractive 
  breeding 
  places, 
  suggested, 
  naturally 
  enough, 
  that 
  these 
  deposits 
  of 
  sand 
  

   or 
  gravel 
  are 
  requisite 
  to 
  the 
  life 
  of 
  the 
  species, 
  and 
  that 
  a 
  careful 
  survey 
  of 
  the 
  

   region 
  would 
  reveal 
  a 
  close 
  correlation 
  between 
  extent 
  of 
  breeding 
  ground 
  of 
  this 
  

   particular 
  character 
  and 
  prevailing 
  local 
  density 
  of 
  the 
  fly. 
  

  

  Attention 
  was 
  first 
  directed 
  toward 
  the 
  " 
  fly 
  beaches," 
  of 
  which 
  there 
  are 
  many 
  

   on 
  island 
  and 
  mainland 
  shores. 
  They 
  are 
  merely 
  open 
  beaches 
  of 
  anything 
  from 
  

   fine 
  white 
  sand 
  to 
  coarse 
  brown 
  gravel 
  or 
  small 
  pebbles 
  mingled 
  with 
  more 
  or 
  less 
  

   sand 
  ; 
  sometimes 
  600 
  to 
  1,000 
  yards 
  or 
  more 
  in 
  length, 
  but 
  usually 
  less, 
  and 
  backed 
  

   up, 
  first 
  by 
  low, 
  bushy, 
  semi-open 
  shelter 
  and 
  secondly, 
  by 
  more 
  massive 
  shelter 
  

   such 
  as 
  may 
  be 
  provided 
  by 
  vine-clad 
  cliffs, 
  but 
  which 
  is 
  nearly 
  always 
  provided 
  by 
  

   forest. 
  

  

  When, 
  as 
  is 
  usually 
  the 
  case, 
  food 
  is 
  plentiful, 
  this 
  combination 
  undoubtedly 
  

   provides 
  the 
  most 
  favourable 
  conditions 
  of 
  life 
  for 
  tsetse 
  that 
  occur 
  in 
  this 
  region. 
  

   The 
  combination 
  of 
  light 
  backed 
  by 
  massive 
  shelter 
  is 
  the 
  most 
  attractive 
  of 
  any 
  

   to 
  the 
  relatively 
  idle 
  male 
  flies, 
  and 
  the 
  combination 
  of 
  light 
  shelter 
  and 
  masses 
  of 
  

   beach 
  sand 
  or 
  gravel 
  affords 
  the 
  type 
  of 
  breeding 
  ground 
  most 
  attractive 
  to 
  female 
  

   flies. 
  

  

  In 
  consequence 
  the 
  maximum 
  degree 
  of 
  density 
  (measured 
  always 
  by 
  density 
  of 
  male 
  

   flies 
  — 
  since 
  activity 
  of 
  females 
  is 
  so 
  variable 
  a 
  quantity) 
  anywhere 
  encountered 
  in 
  the 
  

   course 
  of 
  these 
  investigations, 
  was 
  along 
  such 
  a 
  beach 
  (Zinga 
  Island 
  — 
  Table 
  XXXI). 
  

  

  But 
  though 
  the 
  fly 
  beaches 
  afford 
  the 
  very 
  best 
  condition 
  of 
  life 
  for 
  Glossina 
  

   jpalpalis, 
  other 
  combinations 
  are 
  nearly 
  as 
  good. 
  This 
  is 
  brought 
  out 
  by 
  the 
  table 
  

   ■accompanying 
  (Table 
  XXXI) 
  in 
  which 
  are 
  compared 
  : 
  — 
  

  

  I. 
  Maximum 
  degree 
  of 
  infestation 
  (male 
  density) 
  encountered 
  during 
  fly 
  survey 
  

  

  of 
  islands 
  in 
  January 
  and 
  February 
  1914 
  along 
  fly 
  beaches, 
  with 
  maximum 
  

   infestation 
  encountered 
  elsewhere 
  during 
  same 
  period. 
  

  

  II. 
  Maximum 
  degree 
  of 
  infestation 
  encountered 
  at 
  any 
  time 
  during 
  course 
  

  

  of 
  investigations 
  along 
  fly 
  beaches, 
  with 
  maximum 
  infestation 
  encountered 
  

   at 
  any 
  other 
  points. 
  

  

  These 
  data 
  indicate 
  the 
  absolute 
  maximum 
  of 
  density 
  encountered 
  in 
  the 
  course 
  

   of 
  the 
  investigations. 
  The 
  average 
  density 
  for 
  the 
  entire 
  region 
  was 
  calculated 
  on 
  

   the 
  basis 
  of 
  data 
  from 
  the 
  first 
  300 
  observation 
  points 
  to 
  be 
  very 
  close 
  to 
  12-5. 
  

  

  The 
  density 
  at 
  fly 
  beaches 
  is 
  seen 
  to 
  average 
  something 
  over 
  20'0 
  points 
  higher 
  

   than 
  at 
  the 
  most 
  densely 
  infested 
  points 
  other 
  than 
  fly 
  beaches. 
  At 
  the 
  same 
  time 
  

   infestation 
  elsewhere 
  is 
  often 
  very 
  heavy. 
  

  

  