﻿84 
  REPORT 
  UNITED 
  STATES 
  ENTOMOLOGICAL 
  COMMISSION. 
  

  

  full) 
  we 
  are 
  warranted 
  in 
  saying 
  they 
  were 
  from 
  some 
  point 
  still 
  farther 
  

   south. 
  These 
  facts 
  make 
  it 
  certain 
  that 
  the 
  swarms 
  of 
  May 
  were 
  from 
  

   Texas 
  ; 
  and, 
  as 
  we 
  know 
  from 
  the 
  abundant 
  data 
  received 
  from 
  that 
  

   State, 
  chiefly 
  from 
  the 
  central 
  part. 
  The 
  distance 
  traveled 
  over 
  in 
  this 
  

   movement 
  was 
  some 
  900 
  or 
  1,000 
  miles. 
  From 
  similar 
  testimony 
  it 
  can 
  

   be 
  shown 
  that 
  the 
  locusts 
  hatched 
  in 
  Kansas 
  and 
  Nebraska, 
  in 
  1875, 
  

   moved 
  as 
  far 
  north 
  in 
  their 
  return 
  flights 
  as 
  the 
  Saskatchewan 
  in 
  British 
  

   Columbia, 
  or 
  about 
  thirteen 
  degrees 
  of 
  latitude. 
  Invading 
  swarms 
  from 
  

   the 
  northwest 
  can 
  be 
  occasionally 
  traced 
  an 
  equal 
  distance 
  in 
  their 
  

   movements 
  southward 
  and 
  southeast. 
  

  

  If 
  we 
  count 
  the 
  entire 
  distance 
  back 
  and 
  forth, 
  north 
  and 
  south, 
  which 
  

   some 
  of 
  the 
  locusts 
  evidently 
  traveled 
  in 
  1877, 
  it 
  will 
  certainly 
  exceed 
  a 
  

   thousand 
  miles. 
  It 
  is, 
  therefore, 
  possible 
  for 
  a 
  swarm 
  of 
  the 
  Eocky 
  Mount- 
  

   ain 
  locusts 
  to 
  travel 
  in 
  the 
  course 
  of 
  their 
  migrations 
  a 
  distance 
  of 
  at 
  

   least 
  a 
  thousand 
  miles, 
  with 
  favorable 
  winds, 
  and 
  it 
  is 
  also 
  certain 
  that 
  

   they 
  do 
  frequently 
  traverse 
  this 
  distance. 
  The 
  fact 
  that 
  our 
  locust 
  can 
  

   and 
  frequently 
  does 
  travel 
  a 
  thousand 
  miles 
  being 
  established, 
  there 
  is 
  

   nothing 
  to 
  forbid 
  the 
  supposition 
  that 
  P. 
  migratorius 
  may 
  extend 
  its 
  

   migrations 
  in 
  a 
  single 
  season 
  from 
  the 
  Crimea 
  or 
  farther 
  east 
  to 
  Poland 
  

   and 
  Germany, 
  and 
  that 
  the 
  resulting 
  brood 
  may 
  reach 
  England 
  the 
  fol- 
  

   lowing 
  season 
  if 
  the 
  climatic 
  conditions 
  are 
  "favorable. 
  Nor 
  is 
  there 
  

   anything 
  impossible 
  in 
  the 
  statement 
  of 
  Major 
  Moore, 
  that 
  A. 
  pere- 
  

   grinum 
  passed 
  from 
  Arabia 
  into 
  India 
  in 
  a 
  single 
  migration. 
  C. 
  italicus 
  

   does 
  not 
  appear 
  to 
  be 
  capable 
  of 
  such 
  extended 
  movements. 
  

  

  As 
  a 
  matter 
  of 
  course 
  the 
  extent 
  of 
  their 
  movements 
  depends 
  very 
  

   largely 
  on 
  the 
  winds, 
  as 
  we 
  shall 
  hereafter 
  see 
  when 
  we 
  touch 
  upon 
  this 
  

   point. 
  

  

  3. 
  THE 
  SPACE 
  OVER 
  WHICH 
  A 
  SINGLE 
  FLIGHT 
  MAY 
  EXTEND. 
  

  

  This 
  is 
  a 
  question 
  more 
  difficult 
  to 
  decide, 
  and 
  one 
  in 
  reference 
  to 
  

   which 
  there 
  are 
  still 
  greater 
  differences 
  of 
  opinion. 
  

  

  That 
  it 
  is 
  the 
  usual 
  rule 
  for 
  swarms 
  to 
  alight 
  in 
  the 
  evening 
  and 
  arise 
  

   again 
  in 
  the 
  morning 
  if 
  the 
  wind 
  and 
  weather 
  favor 
  is 
  undoubtedly 
  true, 
  

   as 
  will 
  hereafter 
  be 
  shown 
  ; 
  but 
  that 
  they 
  may, 
  and 
  sometimes 
  do, 
  fly 
  in 
  

   the 
  night, 
  can 
  be 
  clearly 
  shown. 
  As 
  they 
  rely 
  chiefly 
  upon 
  the 
  wind 
  to 
  

   bear 
  them 
  along, 
  the 
  distance 
  to 
  which 
  a 
  single 
  flight 
  may 
  extend 
  de- 
  

   pends 
  upon 
  the 
  rate 
  at 
  which 
  the 
  wind 
  moves 
  and 
  the 
  length 
  of 
  time 
  the 
  

   locusts 
  can 
  sustain 
  themselves 
  in 
  the 
  air. 
  That 
  they 
  can 
  sustain 
  them- 
  

   selves 
  an 
  entire 
  day 
  in 
  the 
  air 
  is 
  too 
  well 
  established 
  to 
  require 
  any 
  fur- 
  

   ther 
  proof 
  here. 
  The 
  experience 
  of 
  1877 
  led 
  many 
  persons 
  in 
  the 
  West 
  

   to 
  the 
  conclusion 
  that 
  they 
  can 
  remain 
  in 
  the 
  air 
  for 
  days 
  without 
  com- 
  

   ing 
  down. 
  While 
  this 
  is 
  an 
  extreme 
  opinion, 
  there 
  are 
  incontrovertible 
  

   facts 
  which 
  go 
  to 
  prove 
  that 
  they 
  do 
  sometimes 
  continue 
  their 
  flights 
  

   for 
  at 
  least 
  an 
  entire 
  day 
  or 
  more. 
  

  

  The 
  rate 
  at 
  which 
  they 
  travel 
  is 
  variously 
  estimated 
  at 
  from 
  three 
  to 
  

  

  