﻿76 
  REPOET 
  UNITED 
  STATES 
  ENTOMOLOGICAL 
  COMMISSION. 
  

  

  move 
  northward, 
  as 
  was 
  the 
  case 
  in 
  1867 
  and 
  1874, 
  and 
  to 
  a 
  large 
  extent 
  

   in 
  1876. 
  Experience 
  has 
  now 
  also 
  enabled 
  those 
  who 
  have 
  carefully 
  

   .studied 
  their 
  characteristics 
  to 
  distinguish, 
  in 
  most 
  cases, 
  " 
  invaders" 
  

   from 
  those 
  hatched 
  in 
  the 
  temporary 
  regions. 
  A 
  corresponding 
  fact 
  in 
  

   the 
  case 
  of 
  A. 
  peregrinum 
  will 
  hereafter 
  be 
  noticed, 
  where 
  the 
  difference 
  

   in 
  color 
  alone 
  is 
  sufficient 
  to 
  distinguish 
  between 
  the 
  invading 
  and 
  

   returning 
  swarms. 
  In 
  the 
  case 
  of 
  C. 
  spretus 
  the 
  difference 
  in 
  color 
  is 
  

   slight, 
  the 
  most 
  marked 
  being 
  the 
  somewhat 
  fiery 
  red 
  of 
  the 
  pronotum 
  

   in 
  the 
  invaders 
  ; 
  and 
  the 
  position 
  of 
  the 
  wings 
  in 
  repose 
  presents 
  also 
  a 
  

   variation, 
  Practice 
  and 
  experience 
  will 
  even 
  enable 
  those 
  who 
  have 
  

   never 
  paid 
  any 
  attention 
  to 
  the 
  study 
  of 
  entomology 
  to 
  distinguish 
  

   between 
  the 
  two. 
  

  

  The 
  first 
  supposition, 
  which 
  appears 
  very 
  plausible, 
  fails 
  also, 
  in 
  part 
  

   at 
  least, 
  when 
  we 
  test 
  it 
  by 
  the 
  facts. 
  In 
  the 
  first 
  place, 
  the 
  intermediate 
  

   plains 
  where 
  he 
  swarms 
  would 
  have 
  to 
  develop 
  are 
  so 
  frequently 
  traversed 
  

   now 
  by 
  stockmen 
  that 
  the 
  fact 
  of 
  their 
  presence 
  would 
  be 
  communicated. 
  

   In 
  the 
  second 
  place, 
  it 
  is 
  now 
  a 
  well-ascertained 
  fact 
  that 
  locusts 
  hatched 
  

   .anywhere 
  in 
  the 
  temporary 
  region 
  south 
  of 
  the 
  southern 
  line 
  of 
  Dakota 
  

   almost 
  always 
  move 
  northward 
  when 
  they 
  begin 
  to 
  fly, 
  whereas 
  the 
  sup- 
  

   position 
  requires 
  them 
  to 
  go 
  south 
  or 
  southeast. 
  Thirdly, 
  as 
  we 
  know, 
  

   from 
  positive 
  data, 
  the 
  returning 
  swarms 
  from 
  as 
  far 
  south 
  as 
  Texas 
  

   reach 
  Western 
  Dakota 
  and 
  even 
  into 
  Montana, 
  it 
  is 
  therefore 
  highly 
  

   probable 
  that 
  the 
  invading 
  swarms 
  extend 
  their 
  flight 
  in 
  a 
  single 
  season 
  a 
  

   like 
  distance 
  southward. 
  Lastly, 
  the 
  facts 
  ascertained, 
  although 
  showing 
  

   .some 
  exceptions, 
  warrant 
  the 
  general 
  conclusion 
  as 
  we 
  have 
  stated 
  it.* 
  

  

  ' 
  As 
  illustrating 
  this, 
  we 
  present 
  the 
  following 
  facts 
  in 
  reference 
  to 
  

   1875 
  and 
  1876, 
  the 
  former 
  being 
  considered 
  a 
  year 
  of 
  "returning 
  swarms" 
  

   from 
  the 
  temporary 
  region, 
  and 
  the 
  latter 
  a 
  year 
  of 
  a 
  invading 
  swarms" 
  

   .from 
  the 
  permanent 
  region. 
  Most 
  of 
  the 
  facts 
  stated 
  will 
  be 
  found 
  scat- 
  

   tered 
  through 
  our 
  former 
  report. 
  

  

  1875. 
  — 
  In 
  Texas 
  a 
  swarm 
  arrived 
  at 
  Eagle 
  Pass 
  from 
  the 
  north 
  in 
  

   September, 
  " 
  but 
  north 
  of 
  this 
  State 
  up 
  to 
  the 
  United 
  States 
  boundary 
  

   line 
  there 
  was 
  no 
  general 
  invasion 
  from 
  the 
  northwest." 
  

  

  In 
  Indian 
  Territory 
  locusts 
  hatched 
  out 
  this 
  year 
  in 
  large 
  numbers, 
  

   .and 
  "during 
  the 
  month 
  of 
  May 
  they 
  departed 
  in 
  a 
  generally 
  north 
  and 
  

   west 
  direction." 
  Large 
  numbers 
  flew 
  westward. 
  

  

  In 
  reference 
  to 
  Kansas, 
  the 
  record 
  states 
  that 
  " 
  the 
  locusts 
  hatched 
  

   /out 
  mostly 
  in 
  April 
  and 
  early 
  May, 
  and 
  became 
  fledged 
  May 
  28 
  to 
  June 
  

   15, 
  and 
  then 
  all 
  flew 
  in 
  a 
  general 
  northwest 
  direction," 
  and 
  that 
  "there 
  

   were 
  no 
  invasions 
  from 
  the 
  north 
  or 
  west 
  that 
  year." 
  

  

  The 
  same 
  thing 
  was 
  also 
  true 
  in 
  reference 
  to 
  Nebraska, 
  but 
  some 
  of 
  

   the 
  swarms 
  which 
  flew 
  north 
  in 
  June 
  appear 
  to 
  have 
  returned 
  southward 
  

   in 
  August, 
  the 
  diseased 
  condition 
  of 
  the 
  latter 
  showing 
  that 
  they 
  had 
  

   /evidently 
  been 
  hatched 
  in 
  the 
  temporary 
  region. 
  172 
  

  

  172 
  See 
  Appendix, 
  pp. 
  129 
  and 
  130, 
  First 
  Report. 
  

   Note. 
  — 
  Facts 
  recently 
  ascertained 
  appear 
  to 
  somewhat 
  modify 
  this 
  conclusion. 
  

  

  