﻿366 
  

  

  W. 
  F. 
  FISKE. 
  

  

  Table 
  XII. 
  

  

  Catch 
  of 
  Fly 
  at 
  Crocodile 
  Point, 
  Bulago 
  Island, 
  showing 
  Existence 
  of 
  Rapid 
  

  

  Movement 
  along 
  Shore. 
  

  

  Date. 
  

  

  Catch 
  of 
  Fly. 
  

  

  Density 
  of 
  Active 
  Fly.* 
  

  

  Total. 
  

  

  Females. 
  

  

  Males. 
  

  

  Females. 
  Total. 
  

  

  .1 
  

  

  5th 
  November 
  1913 
  

  

  10th 
  „ 
  „ 
  

  

  11th 
  „ 
  „ 
  

  

  12th 
  

  

  13th 
  „ 
  „ 
  

  

  564 
  

   630 
  

   944 
  

   167 
  

   435 
  

  

  27 
  % 
  

   20 
  % 
  

  

  28 
  % 
  

   18 
  % 
  

  

  29 
  % 
  

  

  14-2 
  

   16-0 
  

   125 
  

   103 
  

   14-7 
  

  

  5-8 
  

   4-0 
  

   5-0 
  

   2-4 
  

   6-0 
  

  

  20-0 
  

   20-0 
  

   175 
  

   12-5f 
  

  

  20-7 
  

  

  Totals 
  and 
  averages 
  1st 
  experiment 
  

  

  2740 
  

  

  24-4 
  % 
  

  

  135 
  

  

  4-6 
  

  

  18-1 
  

  

  17th 
  January 
  1914 
  . 
  . 
  

  

  20th 
  „ 
  „ 
  

  

  21st 
  „ 
  „ 
  

  

  22nd 
  „ 
  „ 
  

  

  912 
  

  

  1102 
  

  

  303 
  

  

  606 
  

  

  40-3 
  % 
  

  

  48-2 
  % 
  

   44-2 
  % 
  

   48-0 
  % 
  

  

  24-4 
  

   27-5 
  

   11-3 
  

   26-5 
  

  

  17-1 
  

  

  26-4 
  

  

  9-0 
  

  

  28-9 
  

  

  42-5 
  

   53-9 
  

   20*3t 
  

   55-4 
  

  

  Totals 
  and 
  averages 
  2nd 
  experiment 
  

  

  2923 
  

  

  45-2 
  % 
  

  

  227 
  

  

  20-3 
  

  

  42-9 
  

  

  * 
  " 
  Density 
  " 
  is 
  the 
  number 
  of 
  flies 
  caught 
  per 
  fly-boy 
  per 
  hour. 
  

  

  f 
  These 
  days 
  were 
  somewhat 
  dull 
  and 
  overcast, 
  rendering 
  flies 
  inactive. 
  

  

  The 
  fact 
  that 
  density 
  of 
  both 
  sexes 
  was 
  perfectly 
  maintained 
  on 
  the 
  13th 
  November 
  

   after 
  four 
  consecutive 
  days 
  of 
  catching, 
  when 
  viewed 
  in 
  the 
  light 
  of 
  the 
  results 
  of 
  less 
  

   extensive 
  catchings 
  on 
  Tavu 
  (Table 
  V) 
  and 
  Lu]a 
  (Tables 
  VI 
  and 
  VII), 
  can 
  only 
  be 
  

   explained 
  by 
  the 
  movements 
  of 
  fly 
  along 
  shore, 
  and 
  these 
  movements 
  must 
  be 
  quite 
  

   free 
  and 
  rapid 
  in 
  order 
  to 
  account 
  for 
  it. 
  

  

  Notwithstanding 
  the 
  semi-isolated 
  position 
  of 
  Crocodile 
  Point, 
  as 
  many 
  flies 
  

   penetrated 
  its 
  area 
  each 
  day 
  as 
  were 
  caught 
  on 
  it, 
  leaving 
  no 
  other 
  conclusion 
  possible 
  

   than 
  that, 
  if 
  no 
  flies 
  had 
  been 
  caught, 
  as 
  many 
  would 
  have 
  moved 
  away 
  from 
  it. 
  

   Otherwise 
  stated, 
  the 
  fly 
  population 
  of 
  this 
  region 
  was 
  so 
  far 
  from 
  permanently 
  

   fixed 
  there 
  that 
  hardly 
  any 
  individuals 
  sojourned 
  there 
  for 
  more 
  than 
  a 
  single 
  day. 
  

  

  The 
  experiment 
  of 
  the 
  5th 
  to 
  13th 
  November 
  1913 
  was 
  repeated 
  on 
  the 
  17th 
  to 
  

   22nd 
  January 
  1914 
  (Table 
  XII) 
  and 
  completely 
  confirmed 
  it. 
  The 
  conclusions 
  

   were 
  subsequently 
  confirmed 
  in 
  various 
  other 
  ways, 
  and 
  there 
  is 
  no 
  doubt 
  that 
  the 
  

   flies 
  of 
  this 
  species 
  move 
  freely 
  about 
  from 
  place 
  to 
  place, 
  forming 
  continuous 
  streams 
  

   of 
  fly 
  traffic 
  along 
  the 
  shores 
  of 
  lakes, 
  banks 
  of 
  streams, 
  and, 
  it 
  was 
  subsequently 
  

   ascertained, 
  along 
  the 
  borders 
  of 
  woodland, 
  game 
  trails 
  or 
  human 
  pathways, 
  etc. 
  

  

  Ill 
  (b). 
  Movement 
  of 
  the 
  Sexes 
  along 
  the 
  Lake 
  Shore. 
  

  

  Although 
  it 
  was 
  impossible 
  to 
  reduce 
  the 
  local 
  density 
  of 
  fly 
  under 
  such 
  conditions 
  

   as 
  exist 
  at 
  Crocodile 
  Point 
  if 
  an 
  interval 
  of 
  several 
  hours 
  is 
  permitted 
  to 
  elapse 
  between 
  

   periods 
  of 
  catching, 
  it 
  was 
  easily 
  possible 
  to 
  reduce 
  the 
  density 
  of 
  male 
  flies 
  — 
  not 
  

   of 
  active 
  females 
  — 
  by 
  even 
  a 
  single 
  hour's 
  catching, 
  provided 
  no 
  interval 
  elapsed 
  

  

  