﻿INVESTIGATIONS 
  INTO 
  THE 
  BIONOMICS 
  OF 
  GLOSSINA 
  PALPALIS. 
  

  

  439 
  

  

  accompanying 
  table 
  (Table 
  XXXVI). 
  The 
  two 
  islands 
  of 
  Ziro 
  and 
  Kerenge 
  were 
  

   very 
  densely 
  infested 
  by 
  spiders, 
  but 
  otherwise 
  they 
  appeared 
  to 
  be 
  in 
  all 
  respects 
  

   as 
  favourable 
  to 
  tsetse 
  as 
  the 
  other 
  islands 
  named 
  in 
  the 
  table. 
  Both 
  were 
  accounted 
  

   * 
  better 
  than 
  Namba 
  " 
  and 
  " 
  as 
  good 
  as 
  Bulago 
  " 
  in 
  the 
  final 
  summing 
  up 
  of 
  

   impressions 
  gained 
  during 
  the 
  several 
  days 
  spent 
  in 
  the 
  survey 
  of 
  each. 
  

  

  Table 
  XXXVI. 
  

   Effect 
  of 
  Spider 
  on 
  Density 
  of 
  Glossina 
  palpalis. 
  

  

  Island. 
  

  

  Date. 
  

  

  Character 
  of 
  Environment. 
  

  

  Shelter. 
  

  

  Breeding 
  

   grounds. 
  

  

  Food. 
  

  

  Spider. 
  

  

  Infestation. 
  

  

  Male 
  

   density. 
  

  

  Female 
  

   ratio. 
  

  

  Bulago 
  

   Nsadzi 
  . 
  

   Kitebo 
  . 
  

   Namba 
  

   Ziro 
  . 
  

   Kerenge 
  

  

  Jan. 
  

  

  1914 
  

  

  Dec. 
  

   Jan. 
  

   Feb. 
  

  

  1913 
  

   1914 
  

   1914 
  

  

  >j 
  

  

  » 
  

  

  Good 
  

  

  Very 
  good 
  

   Good 
  

  

  Good 
  

  

  J 
  J 
  

  

  Poor 
  

   Good 
  

  

  Good 
  

  

  None 
  

  

  27-5 
  

  

  ,5 
  . 
  . 
  

  

  59 
  • 
  • 
  

  

  18-4 
  

  

  »> 
  • 
  • 
  

  

  5» 
  * 
  * 
  

  

  14-5 
  

  

  Very 
  good 
  

  

  >J 
  • 
  • 
  

  

  9-4 
  

  

  Good 
  ^\ 
  

  

  Exceeding- 
  

  

  / 
  54 
  

  

  / 
  

  

  ly 
  many 
  

  

  I 
  3*8 
  

  

  29*0 
  

   24-6 
  

   33-7 
  

   7'9 
  

   23*7 
  

   24*7 
  

  

  /o 
  

   /o 
  

   /o 
  

   /o 
  

  

  Average 
  infestation 
  of 
  islands 
  with 
  no 
  spider 
  . 
  . 
  

  

  „ 
  „ 
  many 
  spiders 
  

  

  Reduced 
  infestation 
  attributed 
  to 
  spider 
  

  

  17*2 
  

   4-6 
  

  

  23-3 
  % 
  

   24'2 
  % 
  

  

  12'6 
  = 
  73'3 
  

  

  Numerous 
  other 
  islands 
  were 
  found 
  to 
  be 
  heavily 
  or 
  excessively 
  infested 
  by 
  

   spiders, 
  but 
  in 
  the 
  case 
  of 
  no 
  others 
  was 
  comparison 
  with 
  spider-free 
  islands 
  so 
  

   generally 
  fair. 
  

  

  •It 
  is 
  possible 
  that 
  if 
  conditions 
  of 
  life 
  otherwise 
  were 
  less 
  favourable 
  than 
  on 
  

   Ziro 
  and 
  Kerenge, 
  the 
  spiders 
  in 
  comparable 
  density 
  might 
  prove 
  an 
  exterminative 
  

   destructor. 
  The 
  islands 
  of 
  Dwanga 
  Mkuru, 
  Dwanga 
  Mto 
  and 
  Dwasengwe 
  noted 
  

   in 
  Table 
  XXXII 
  (p. 
  422) 
  as 
  very 
  lightly 
  or 
  not 
  at 
  all 
  infested 
  may 
  possibly 
  owe 
  

   freedom 
  from 
  fly 
  to 
  infestations 
  by 
  spiders, 
  which 
  was 
  fairly 
  heavy 
  in 
  each 
  case, 
  

   as 
  well 
  as 
  to 
  absence 
  of 
  breeding 
  grounds. 
  

  

  (2). 
  Dragonflies. 
  

  

  A 
  dragonfly 
  of 
  a 
  rather 
  small 
  and 
  undetermined 
  species 
  occurs 
  commonly, 
  but 
  

   irregularly 
  distributed, 
  throughout 
  the 
  islands 
  and 
  riparian 
  belt. 
  There 
  are 
  other 
  

   species, 
  but 
  this 
  one 
  is 
  conspicuous 
  for 
  its 
  numbers 
  and 
  for 
  a 
  well 
  marked 
  habit 
  of 
  

   following 
  moving 
  animals 
  and 
  man 
  and 
  feeding 
  ofT 
  the 
  flies 
  which 
  are 
  attracted 
  to 
  

   them. 
  Large 
  numbers 
  — 
  in 
  exceptional 
  cases 
  perhaps 
  as 
  many 
  as 
  40 
  or 
  50 
  — 
  of 
  these 
  

   dragonflies 
  may 
  follow 
  a 
  man 
  along 
  the 
  open 
  shore, 
  and 
  they 
  have 
  been 
  observed 
  to 
  

   capture 
  tsetse 
  many 
  times. 
  

  

  The 
  species 
  varies 
  greatly 
  in 
  local 
  density 
  from 
  one 
  island 
  or 
  district 
  to 
  another. 
  

   It 
  was 
  observed 
  most 
  abundantly 
  along 
  the 
  western 
  shore 
  of 
  Bukone 
  Island 
  in 
  

   September 
  1914. 
  A 
  fairly 
  complete 
  survey 
  of 
  the 
  island 
  was 
  made 
  and 
  the 
  infesta- 
  

   tion 
  indicated 
  (male 
  density 
  8*6 
  ; 
  female 
  ratio 
  23*4 
  per 
  cent.) 
  was 
  considerably 
  

  

  