﻿INVESTIGATIONS 
  INTO 
  THE 
  BIONOMICS 
  OF 
  GLOSSINA 
  PALPALIS. 
  411 
  

  

  designed 
  in 
  part 
  to 
  confirm 
  conclusions 
  drawn 
  from 
  co-ordination 
  of 
  data 
  collected 
  

   in 
  the 
  course 
  of 
  the 
  Island 
  survey, 
  viz. 
  : 
  — 
  

  

  I. 
  If 
  protection 
  (shelter 
  and 
  breeding 
  ground) 
  is 
  more 
  than 
  adequate, 
  range 
  

  

  and 
  density 
  of 
  Glossina 
  palpalis 
  are 
  controlled 
  by 
  quantity 
  of 
  food 
  of 
  

   preferred 
  sorts 
  occurring 
  within 
  range 
  or 
  reach 
  of 
  flies 
  from 
  both 
  kinds 
  

   of 
  protection 
  required 
  (see 
  fig. 
  6 
  and 
  note 
  following). 
  

  

  II. 
  Food, 
  even 
  of 
  the 
  most 
  favoured 
  sorts, 
  is 
  valueless 
  to 
  the 
  species 
  unless 
  

  

  protection 
  (of 
  both 
  sorts, 
  shelter 
  and 
  breeding 
  grounds) 
  occurs 
  within 
  

   range 
  or 
  reach 
  of 
  individual 
  flies 
  from 
  it. 
  

  

  III. 
  The 
  distance 
  separating 
  food 
  from 
  protection 
  (as 
  it 
  may 
  be 
  measured 
  

   by 
  yards) 
  is 
  a 
  factor 
  of 
  the 
  very 
  first 
  importance 
  in 
  determining 
  the 
  

   prevailing 
  degree 
  of 
  infestation 
  by 
  the 
  species. 
  

  

  VI 
  (g). 
  Effect 
  of 
  Crocodile 
  m 
  Range 
  and 
  Density 
  of 
  Fly 
  a§@ng 
  Shore. 
  

  

  The 
  curve 
  in 
  the 
  accompanying 
  graph 
  (fig. 
  6) 
  illustrates 
  the 
  variations 
  in 
  local 
  

   density 
  of 
  Glossina 
  palpalis 
  along 
  a 
  reach 
  of 
  four 
  miles 
  of 
  shore 
  which 
  was 
  surveyed 
  

   in 
  May 
  and 
  June 
  1915. 
  

  

  The 
  foreshore 
  at 
  these 
  points 
  was 
  an 
  open 
  sandy 
  beach, 
  continuous 
  except 
  at 
  

   observation 
  points 
  5 
  and 
  9, 
  where 
  it 
  was 
  cut 
  by 
  small 
  creeks. 
  Immediately 
  behind 
  

   the 
  beach 
  was 
  a 
  belt 
  of 
  open 
  grass-land 
  with 
  a 
  few 
  scattered 
  bushes 
  — 
  not 
  enough 
  

   to 
  afford 
  shelter 
  for 
  fly. 
  The 
  soil 
  was 
  beach 
  sand, 
  and 
  this 
  open 
  belt 
  or 
  natural 
  

   clearing 
  was 
  from 
  40 
  to 
  100 
  yards 
  in 
  width. 
  Behind 
  it 
  was 
  thick 
  bush, 
  jungle 
  

   and 
  forest, 
  affording 
  excellent 
  shelter 
  for 
  fly; 
  good 
  breeding 
  ground 
  was 
  almost 
  

   continuous 
  along 
  the 
  border 
  of 
  the 
  woodland 
  from 
  point 
  1 
  to 
  point 
  9. 
  

  

  Food 
  only 
  was 
  lacking. 
  There 
  were 
  tracks 
  of 
  hippo, 
  bush-buck, 
  bush-pig, 
  water- 
  

   buck 
  and 
  buffalo 
  in 
  the 
  open 
  belt, 
  but 
  the 
  animals 
  were 
  not 
  seen 
  ; 
  their 
  spoor 
  was 
  

   not 
  fresh, 
  and 
  they 
  were 
  obviously 
  only 
  occasional 
  visitors. 
  Crocodiles 
  and 
  the 
  

   fresh 
  spoor 
  of 
  crocodiles 
  were 
  seen 
  along 
  the 
  water's 
  edge, 
  but 
  they 
  were 
  effectually 
  

   cut 
  off 
  from 
  shelter 
  by 
  the 
  open 
  belt, 
  and 
  beyond 
  reach 
  of 
  flies. 
  

  

  Only 
  at 
  points 
  5 
  and 
  9, 
  where 
  the 
  creeks 
  cut 
  through 
  the 
  open 
  belt 
  and 
  sand 
  

   beach, 
  did 
  the 
  crocodiles 
  come 
  into 
  range 
  or 
  reach 
  of 
  flies 
  from 
  shelter. 
  At 
  these- 
  

   points 
  they 
  found 
  harbour 
  in 
  the 
  mouths 
  of 
  the 
  creeks, 
  and 
  basked 
  on 
  their 
  banks 
  

   within 
  easy 
  reach 
  of 
  the 
  flies 
  from 
  shelter, 
  and 
  here, 
  as 
  the 
  graph 
  clearly 
  shows, 
  

   two 
  small 
  semi-distinct 
  colonies 
  of 
  fly 
  existed. 
  There 
  could 
  be 
  no 
  doubt 
  that 
  the 
  

   existence 
  of 
  these 
  colonies 
  was 
  due 
  to 
  the 
  presence 
  of 
  a 
  regular 
  supply 
  of 
  food, 
  

   represented 
  by 
  the 
  crocodiles, 
  within 
  range 
  or 
  reach 
  of 
  the 
  flies 
  from 
  shelter. 
  

  

  VII. 
  The 
  Breeding 
  Grounds 
  of 
  Glossina 
  Palpalis. 
  

   It 
  is 
  a 
  strongly 
  marked 
  characteristic 
  of 
  Glossina 
  palpalis 
  to 
  seek 
  specifically 
  pro- 
  

   tected 
  spots 
  wherein 
  to 
  deposit 
  its 
  larvae, 
  and 
  extraordinary 
  accumulations 
  of 
  puparia 
  

   and 
  the 
  empty 
  shells 
  of 
  them 
  (from 
  which 
  adults 
  have 
  issued) 
  may 
  be 
  found 
  in 
  

   especially 
  attractive 
  situations. 
  

  

  To 
  what 
  extent 
  the 
  species 
  is 
  dependent 
  on 
  breeding 
  grounds 
  of 
  sorts 
  easily 
  

   found, 
  and 
  recognisable 
  as 
  such, 
  was 
  unknown, 
  and 
  it 
  was 
  one 
  of 
  the 
  principle 
  objects 
  

   of 
  these 
  investigations 
  to 
  secure 
  positive 
  information 
  on 
  this 
  point, 
  and 
  in 
  the 
  hope 
  

   that 
  it 
  would 
  prove 
  practicable 
  to 
  control 
  the 
  density 
  of 
  the 
  insect 
  by 
  seeking 
  and 
  

   destroying 
  its 
  specific 
  breeding 
  places. 
  

   (659) 
  e 
  

  

  