﻿INVESTIGATIONS 
  INTO 
  THE 
  BIONOMICS 
  OF 
  GLOSSINA 
  PALPALIS. 
  

  

  353 
  

  

  But 
  what 
  becomes 
  of 
  the 
  surplus 
  males 
  in 
  localities 
  where 
  females 
  predominate, 
  

   or 
  of 
  surplus 
  females, 
  when, 
  as 
  usually 
  is 
  the 
  case, 
  males 
  predominate, 
  were 
  questions 
  

   that 
  had 
  not 
  been 
  answered 
  when 
  these 
  investigations 
  were 
  begun. 
  Whatever 
  

   the 
  explanation 
  might 
  be, 
  it 
  was 
  certain 
  to 
  be 
  intimately 
  involved 
  with 
  phases 
  in 
  

   the 
  bionomics 
  of 
  tsetse 
  the 
  nature 
  of 
  which 
  could 
  only 
  be 
  guessed, 
  but 
  the 
  importance 
  

   of 
  which 
  could 
  not 
  be 
  doubted. 
  

  

  A 
  minor 
  problem 
  was 
  thus 
  denned 
  which 
  served 
  as 
  a 
  starting 
  point 
  for 
  further 
  

   investigations 
  into 
  the 
  broad 
  and 
  complicated 
  subject 
  of 
  the 
  bionomics 
  of 
  Glossina 
  

   palpalis, 
  and 
  the 
  first 
  field-work 
  done 
  was 
  the 
  series 
  of 
  experiments 
  an 
  account 
  of 
  

   which 
  follows. 
  

  

  1(a). 
  Experiment 
  to 
  determine 
  if 
  Variations 
  in 
  Sex 
  Ratio 
  of 
  Glossina 
  palpalis 
  are 
  

   due 
  to 
  differences 
  in 
  the 
  purely 
  local, 
  or 
  in 
  the 
  climatic 
  or 
  seasonal 
  Conditions 
  

   of 
  Life. 
  

  

  The 
  Islands 
  of 
  Bulago 
  and 
  Tavu 
  (fig. 
  1) 
  are 
  separated 
  by 
  only 
  a 
  few 
  thousand 
  

   yards. 
  Tavu 
  is 
  much 
  the 
  smaller 
  and 
  differs 
  also 
  in 
  topography 
  and 
  vegetation. 
  

   But 
  the 
  two 
  islands 
  are 
  so 
  near 
  together 
  that 
  any 
  difference 
  in 
  sex 
  ratio, 
  if 
  constant 
  

   and 
  if 
  occurring 
  at 
  the 
  same 
  seasons 
  of 
  the 
  year, 
  would 
  necessarily 
  be 
  due 
  to 
  purely 
  

   local 
  conditions. 
  

  

  Large 
  collections 
  of 
  fly 
  were 
  made 
  on 
  the 
  two 
  islands 
  as 
  shown 
  in 
  Table 
  I. 
  There 
  

   was 
  considerable 
  variation 
  in 
  sex 
  ratio 
  observed 
  on 
  Bulago 
  on 
  different 
  days 
  

   (when 
  collections 
  were 
  made 
  at 
  different 
  points 
  on 
  the 
  island), 
  but 
  in 
  the 
  total 
  

   catch 
  of 
  4,405 
  flies 
  there 
  were 
  proportionately 
  twice 
  as 
  many 
  females 
  as 
  in 
  the 
  

   total 
  catch 
  of 
  3,126 
  flies 
  from 
  Tavu. 
  This 
  difference 
  could 
  only 
  be 
  attributed 
  to 
  

   purely 
  local 
  differences 
  in 
  conditions 
  of 
  life 
  between 
  these 
  two 
  islands. 
  

  

  Table 
  I. 
  

  

  Catch 
  of 
  Fly 
  from 
  Bulago 
  and 
  Tavu 
  Islands, 
  showing 
  relatively 
  constant 
  difference 
  

  

  in 
  Sex 
  Ratio. 
  

  

  1913. 
  

  

  Island. 
  

  

  Daily 
  Catch. 
  

  

  Total 
  Catch. 
  

  

  Total. 
  

  

  Females. 
  

  

  Total. 
  

  

  Females. 
  

  

  1st 
  No 
  

  

  2nd 
  , 
  

  

  3rd 
  , 
  

  

  4th 
  , 
  

  

  5th 
  , 
  

  

  6th 
  , 
  

  

  10th 
  , 
  

  

  11th 
  , 
  

  

  12th 
  , 
  

  

  13 
  th 
  , 
  

  

  5th 
  , 
  

  

  6th 
  , 
  

  

  7th 
  , 
  

  

  8th 
  , 
  

  

  v. 
  . 
  . 
  

  

  9 
  * 
  • 
  

  

  Bulago 
  

  

  >5 
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  • 
  

  

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  * 
  ' 
  

   J, 
  • 
  • 
  

  

  >5 
  • 
  • 
  

  

  5, 
  • 
  • 
  

  

  Tavu 
  '. 
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   >t 
  . 
  . 
  

   j» 
  • 
  • 
  

  

  170 
  

   18 
  

   60 
  

   630 
  

   564 
  

   656 
  

   651 
  

  

  1057 
  

   167 
  

   435 
  

   136 
  

  

  1179 
  

   945 
  

   866 
  

  

  35 
  % 
  

  

  IV 
  % 
  

  

  24 
  % 
  

  

  25 
  % 
  

  

  27 
  % 
  

  

  18 
  % 
  

   20 
  o 
  /o 
  

  

  27 
  o 
  /o 
  

  

  18 
  % 
  

   29 
  % 
  

  

  4 
  % 
  

   8-3 
  % 
  

  

  18 
  % 
  

   13 
  % 
  

  

  170 
  

  

  188 
  

  

  248 
  

  

  878 
  

  

  1442 
  

  

  2098 
  

  

  2749 
  

  

  3803 
  

  

  3970 
  

  

  4405 
  

  

  136 
  

  

  1315 
  

  

  2260 
  

  

  3126 
  

  

  35 
  % 
  

   33 
  % 
  

  

  32 
  % 
  

   28 
  % 
  

   27 
  % 
  

   25 
  % 
  

   24 
  o/ 
  

   24-5 
  % 
  

  

  24 
  o/o 
  

  

  25 
  % 
  

   4 
  % 
  

   7-8 
  % 
  

  

  12 
  % 
  

   12-4 
  % 
  

  

  