﻿444 
  W. 
  F. 
  FISKE. 
  

  

  It 
  is 
  very 
  difficult 
  to 
  study 
  the 
  effect 
  of 
  storms 
  on 
  adult 
  flies 
  — 
  mainly 
  because 
  

   they 
  are 
  almost 
  impossible 
  to 
  find 
  except 
  when 
  active. 
  One 
  can 
  only 
  be 
  sure 
  that 
  

   their 
  hiding 
  places 
  have 
  been 
  discovered 
  by 
  searching 
  at 
  hours 
  when 
  none 
  are 
  

   active 
  — 
  for 
  they 
  are 
  quick 
  to 
  take 
  flight 
  if 
  disturbed 
  and 
  quickly 
  confused 
  with 
  

   active 
  flies 
  if 
  there 
  are 
  any 
  about. 
  

  

  It 
  is 
  a 
  strongly 
  marked 
  characteristic 
  of 
  the 
  active 
  flies 
  to 
  seek 
  shelter 
  when 
  a 
  

   storm 
  is 
  brewing, 
  especially 
  the 
  females, 
  as 
  shown 
  by 
  the 
  accompanying 
  graph 
  

   (fig. 
  10), 
  which 
  was 
  secured 
  in 
  the 
  course 
  of 
  an 
  experiment 
  with 
  the 
  streams 
  of 
  

   moving 
  flies. 
  The 
  catches 
  were 
  made 
  at 
  a 
  point 
  when 
  all 
  the 
  " 
  resident 
  " 
  flies 
  

   had 
  been 
  caught 
  off, 
  and 
  only 
  those 
  in 
  the 
  passing 
  streams 
  were 
  being 
  caught. 
  

   About 
  11 
  o'clock 
  a 
  storm 
  gathered 
  on 
  the 
  horizon. 
  The 
  temperature 
  fell 
  a 
  few 
  

   degrees, 
  and 
  a 
  light 
  breeze 
  sprung 
  up. 
  This 
  was 
  all 
  that 
  happened. 
  The 
  sun 
  

   was 
  not 
  obscured, 
  and 
  the 
  storm 
  did 
  not 
  come 
  within 
  miles 
  of 
  the 
  island 
  (Manene, 
  

   17th 
  March 
  1915), 
  but 
  almost 
  half 
  the 
  females 
  sought 
  shelter, 
  and 
  remained 
  secluded 
  

   until 
  the 
  cool 
  breeze 
  dropped. 
  Then 
  they 
  quickly 
  became 
  even 
  more 
  active 
  than 
  

   before. 
  

  

  Certainly 
  the 
  insects 
  would 
  not 
  flee 
  so 
  quickly 
  at 
  first 
  signs 
  of 
  a 
  storm 
  unless 
  

   they 
  were 
  fearful 
  of 
  it, 
  and 
  next 
  to 
  sun, 
  storms 
  are 
  probably 
  the 
  most 
  dangerous 
  

   " 
  enemy 
  " 
  of 
  the 
  species. 
  

  

  (3). 
  Flood. 
  

  

  The 
  rising 
  waters 
  of 
  lake 
  or 
  stream 
  may 
  destroy 
  many 
  puparia 
  in 
  breeding 
  grounds 
  

   in 
  sand 
  or 
  gravel 
  deposits, 
  and 
  would 
  destroy 
  many 
  more 
  than 
  is 
  in 
  fact 
  the 
  case 
  

   were 
  it 
  not 
  that 
  the 
  females 
  avoid 
  depositing 
  their 
  larvae 
  in 
  spots 
  too 
  near 
  the 
  

   water. 
  Even 
  on 
  the 
  " 
  fly 
  beaches 
  " 
  it 
  is 
  in 
  the 
  old 
  beach 
  line 
  beyond 
  reach 
  of 
  even 
  

   the 
  heaviest 
  waves 
  that 
  nearly 
  all 
  the 
  large 
  deposits 
  of 
  pupae 
  have 
  been 
  found. 
  

  

  The 
  effect 
  of 
  such 
  a 
  flood 
  tide 
  as 
  that 
  of 
  1906 
  upon 
  the 
  puparia 
  must 
  be 
  very 
  

   destructive, 
  for 
  in 
  May 
  and 
  June 
  of 
  that 
  year 
  there 
  could 
  have 
  been 
  very 
  few 
  good 
  

   breeding 
  places 
  — 
  relatively 
  — 
  beyond 
  reach 
  of 
  the 
  waves 
  (see 
  p. 
  457). 
  

  

  In 
  the 
  bed 
  of 
  the 
  Victoria 
  Nile, 
  some 
  miles 
  from 
  its 
  source, 
  excellent 
  and 
  much 
  

   frequented 
  breeding 
  grounds 
  were 
  found 
  (April 
  1914) 
  at 
  points 
  where 
  they 
  would 
  

   almost 
  certainly 
  be 
  destroyed 
  in 
  May 
  or 
  June. 
  

  

  (4). 
  Fire. 
  

  

  Bush 
  or 
  grass 
  fires 
  are 
  potent 
  factors 
  in 
  the 
  bionomics 
  of 
  Glossina 
  morsitans, 
  but 
  

   at 
  no 
  point 
  visited 
  on 
  the 
  islands 
  or 
  riparian 
  zone 
  of 
  Victoria 
  Nyanza 
  was 
  fire 
  likely 
  

   to 
  affect 
  Glossina 
  palpalis 
  to 
  an 
  appreciable 
  extent. 
  

  

  IX 
  (e). 
  Secondary 
  Environmental 
  Factors 
  detrimental 
  to 
  Glossina. 
  

  

  Whatever 
  benefit 
  may 
  be 
  derived 
  by 
  humanity 
  from 
  the 
  activities 
  of 
  the 
  two 
  

   natural 
  enemies 
  of 
  Glossina 
  palpalis 
  which 
  produced 
  an 
  appreciable 
  effect 
  on 
  its 
  

   density 
  — 
  spider 
  and 
  dragonfly 
  — 
  is 
  inseparably 
  associated 
  with 
  whatever 
  it 
  is 
  which 
  

   permits 
  these 
  entomophagids 
  to 
  multiply 
  to 
  such 
  excessive 
  numbers 
  as 
  is 
  required 
  

   to 
  produce 
  that 
  effect. 
  

  

  