﻿HEIGHT 
  AT 
  WHICH 
  SWARMS 
  MOVE. 
  99 
  

  

  at 
  a 
  height 
  which 
  carries 
  them 
  eDtirely 
  out 
  of 
  view 
  is 
  well 
  known, 
  as 
  

   their 
  notes 
  can 
  frequently 
  be 
  heard 
  overhead 
  when 
  the 
  eye 
  searches 
  in 
  

   vain 
  for 
  them. 
  At 
  what 
  elevation 
  these 
  move 
  it 
  is 
  impossible 
  to 
  tell, 
  

   but 
  it 
  is 
  not 
  probable 
  that 
  it 
  is 
  much, 
  if 
  any. 
  over 
  two 
  miles; 
  and 
  it 
  is 
  

   reasonable 
  to 
  suppose 
  that 
  a 
  height 
  which 
  would 
  render 
  ihem 
  invisible 
  

   would 
  render 
  a 
  swarm 
  of 
  locusts 
  invisible 
  when 
  passing 
  overhead, 
  as 
  the 
  

   latter, 
  as 
  before 
  stated, 
  are 
  seen, 
  not 
  as 
  a 
  mass, 
  but 
  as 
  individuals. 
  

  

  The 
  statement 
  by 
  Mr. 
  Byers, 
  197 
  that 
  while 
  on 
  Long's 
  Peak 
  he 
  observed 
  

   swarms 
  flying 
  over 
  as 
  high 
  as 
  the 
  eye 
  could 
  reach, 
  and 
  that 
  of 
  Mr. 
  Put- 
  

   nam 
  to 
  the 
  same 
  effect, 
  show 
  very 
  conclusively 
  that 
  it 
  is 
  possible 
  for 
  

   them 
  to 
  fly 
  as 
  much 
  above 
  the 
  reach 
  of 
  the 
  natural 
  eye 
  .as 
  the 
  tops 
  of 
  

   Long's 
  and 
  Parry's 
  Peaks 
  are 
  above 
  the 
  plains 
  of 
  Kansas 
  and 
  Nebraska 
  — 
  

   about 
  10,000 
  feet. 
  The 
  writer 
  has 
  taken 
  specimens 
  on 
  the 
  very 
  summit 
  

   of 
  Pike's 
  Peak, 
  brought 
  down, 
  probably, 
  by 
  a 
  preceding 
  shower 
  of 
  rain, 
  

   yet 
  no 
  swarm 
  had 
  been 
  noticed 
  passing 
  over 
  by 
  the 
  Signal 
  Service 
  offi- 
  

   cer 
  in 
  charge 
  of 
  the 
  station. 
  The 
  Signal 
  Service 
  officer 
  at 
  Bismarck 
  

   states 
  that 
  with 
  a 
  glass 
  he 
  observed 
  a 
  swarm 
  on 
  one 
  occasion 
  flying 
  

   above 
  the 
  clouds. 
  

  

  The 
  careful 
  and 
  interesting 
  observations 
  of 
  Dr. 
  A. 
  L. 
  Child, 
  of 
  Platts- 
  

   mouth, 
  Xebr., 
  whose 
  letter 
  has 
  already 
  been 
  quoted, 
  appear 
  to 
  settle 
  

   this 
  point 
  beyond 
  dispute 
  ; 
  and 
  although 
  we 
  have 
  other 
  evidence 
  point- 
  

   ing 
  to 
  the 
  same 
  conclusion, 
  we 
  deem 
  it 
  unnecessary 
  to 
  present 
  it. 
  We 
  

   conclude, 
  therefore, 
  that 
  as 
  a 
  general 
  rule 
  swarms 
  of 
  C. 
  spretus 
  are 
  not 
  

   visible 
  to 
  the 
  natural 
  eye 
  at 
  a 
  height 
  of 
  more 
  than 
  seven 
  or 
  eight 
  thou- 
  

   sand 
  feet 
  above 
  the 
  plains 
  of 
  the 
  temporary 
  region 
  ; 
  that 
  in 
  their 
  long 
  

   flights, 
  when 
  invading 
  and 
  returning, 
  they 
  not 
  only 
  often, 
  but 
  probably 
  

   generally, 
  fly, 
  during 
  part 
  of 
  the 
  distance 
  traversed, 
  so 
  high 
  as 
  to 
  be 
  out 
  

   of 
  sight, 
  and 
  that 
  sometimes 
  they 
  pass 
  above 
  the 
  lower 
  and 
  rain 
  clouds, 
  

   though 
  as 
  a 
  general 
  rule 
  it 
  is 
  only 
  during 
  clear 
  weather, 
  when 
  the 
  sky 
  is 
  

   cloudless, 
  that 
  they 
  fly. 
  

  

  If 
  we 
  are 
  correct 
  in 
  these 
  conclusions, 
  they, 
  together 
  with 
  the 
  fact 
  that 
  

   the 
  locusts 
  also 
  occasionally 
  fly 
  at 
  night, 
  will 
  enable 
  us 
  to 
  understand 
  

   why 
  it 
  is 
  so 
  difficult 
  to 
  trace 
  the 
  flight 
  of 
  a 
  swarm, 
  and 
  will 
  also 
  serve 
  

   as 
  an 
  explanation 
  of 
  much 
  of 
  the 
  mystery 
  that 
  has 
  surrounded 
  their 
  

   movements. 
  

  

  It 
  is 
  somewhat 
  strange 
  that 
  this 
  question 
  should 
  have 
  been 
  overlooked 
  

   by 
  European 
  entomologists, 
  when 
  it 
  would 
  have 
  sufficed 
  as 
  an 
  explana- 
  

   tion 
  of 
  some 
  of 
  the 
  points 
  long 
  in 
  controversy. 
  

  

  Koppen 
  1% 
  says 
  : 
  

  

  The 
  height 
  of 
  the 
  flight 
  is 
  quite 
  variable 
  ; 
  they 
  direct 
  themselves 
  according 
  to 
  the 
  

   wind 
  and 
  weather, 
  and 
  may 
  vary 
  during 
  the 
  continuation 
  of 
  the 
  flight. 
  I 
  observed 
  

   the 
  flight 
  of 
  locusts 
  soon 
  after 
  their 
  last 
  moult 
  ; 
  it 
  was 
  in 
  the 
  evening 
  and 
  on 
  a 
  mod- 
  

   erate 
  west 
  wind; 
  they 
  mostly 
  flew 
  at 
  a 
  height 
  of 
  15 
  or 
  20 
  feet 
  ; 
  single 
  individuals 
  only 
  

   reached 
  a 
  height 
  of 
  40 
  or 
  50 
  feet. 
  

  

  197 
  First 
  Eeport, 
  144. 
  WHeuschr. 
  Siid-Etiss, 
  52. 
  

  

  