﻿32 
  REPORT 
  UNITED 
  STATES 
  ENTOMOLOGICAL 
  COMMISSION. 
  

  

  where 
  they 
  become 
  scattered 
  and 
  lost, 
  except 
  when 
  in 
  uncommonly 
  large 
  

   numbers 
  as 
  in 
  the 
  year 
  1866, 
  when 
  they 
  came 
  as 
  far 
  east 
  as 
  the 
  settled 
  

   portions 
  of 
  these 
  States 
  and 
  did 
  considerable 
  damage. 
  

  

  Those 
  that 
  leave 
  the 
  northern 
  portion 
  of 
  this 
  great 
  center 
  and 
  cross 
  

   over 
  the 
  range 
  into 
  Idaho 
  and 
  Washington 
  Territory, 
  work 
  southwest 
  

   at 
  first, 
  then 
  south 
  through 
  western 
  Idaho 
  and 
  eastern 
  Washington 
  

   Territory, 
  when 
  they 
  turn 
  to 
  the 
  southeast 
  and 
  reach 
  the 
  central 
  region, 
  

   from 
  which 
  they 
  return 
  to 
  the 
  starting 
  point 
  by 
  way 
  of 
  the 
  Snake 
  and 
  

   Madison 
  Yalleys. 
  These 
  movements, 
  however, 
  occur, 
  and 
  for 
  the 
  grea^ter 
  

   part 
  of 
  their 
  course 
  lie, 
  within 
  the 
  Permanent 
  Eegion 
  ; 
  hence 
  they 
  cannot 
  

   be 
  set 
  down 
  as 
  the 
  mode 
  of 
  travel 
  in 
  all 
  portions 
  of 
  the 
  country 
  at 
  times 
  

   visited 
  by 
  their 
  swarms, 
  neither 
  can 
  they 
  be 
  considered 
  as 
  being 
  the 
  

   rule 
  of 
  their 
  flights. 
  

  

  Locusts 
  that 
  follow 
  down 
  the 
  Snake 
  River 
  enter 
  eastern 
  Oregon 
  and 
  

   work 
  their 
  way 
  northward 
  through 
  this 
  State 
  and 
  western 
  Idaho 
  with 
  

   a 
  portion 
  of 
  southeastern 
  Washington 
  Territory, 
  and 
  thence 
  are 
  car- 
  

   ried 
  by 
  the 
  i>revalent 
  winds 
  across 
  the 
  Ooeur 
  d'Alene 
  and 
  Bitter 
  Root 
  

   Mountains 
  into 
  the 
  valleys 
  of 
  the 
  ui)per 
  portions 
  of 
  Clarke's 
  Fork 
  of 
  the 
  

   Columbia. 
  Here 
  they 
  continue 
  working 
  eastward 
  through 
  western 
  

   Montana 
  until 
  they 
  recross 
  the 
  Eocky 
  Moiihtains 
  into 
  the 
  great 
  center 
  

   of 
  Montana 
  and 
  British 
  America, 
  thereby 
  completing 
  the 
  circular 
  move- 
  

   ment. 
  Of 
  course 
  these 
  movements 
  are 
  only 
  noticed 
  in 
  connection 
  with 
  

   the 
  movements 
  of 
  swarms 
  in 
  different 
  portions 
  of 
  the 
  districts 
  embraced, 
  

   and, 
  as 
  just 
  stated, 
  for 
  the 
  most 
  part 
  are 
  confined 
  to 
  the 
  Permanent 
  

   Eegion. 
  

  

  With 
  these 
  facts 
  in 
  reference 
  to 
  the 
  movements 
  of 
  locusts 
  in 
  general 
  

   before 
  us, 
  it 
  will 
  now 
  be 
  in 
  order 
  to 
  mention 
  some 
  of 
  the 
  controlling 
  

   agencies 
  for 
  the 
  various 
  actions 
  of 
  moving 
  swarms 
  ; 
  how 
  it 
  happens 
  

   that 
  they 
  choose 
  these 
  particular 
  routes 
  just 
  mentioned, 
  why 
  at 
  certain 
  

   times 
  of 
  the 
  year 
  the 
  prevailing 
  movements 
  are 
  in 
  one 
  direction 
  and 
  

   just 
  opposite 
  at 
  another, 
  and 
  why 
  it 
  is 
  that 
  a 
  change 
  of 
  wind 
  or 
  the 
  

   advance 
  of 
  a 
  storm 
  or 
  even 
  a 
  decided 
  change 
  of 
  temperature 
  from 
  warm 
  

   to 
  cold 
  brings 
  them 
  to 
  the 
  ground. 
  

  

  When 
  locust 
  swarms 
  start 
  for 
  a 
  flight 
  to 
  some 
  other 
  locality 
  they, 
  as 
  

   a 
  rule, 
  follow 
  a 
  particular 
  direction, 
  which 
  varies 
  much 
  in 
  different 
  sec- 
  

   tions 
  of 
  country, 
  and 
  at 
  different 
  seasons 
  of 
  the 
  year. 
  Any 
  agency 
  that 
  

   interferes 
  with 
  this 
  yiarticular 
  course 
  has 
  a 
  tendency 
  to 
  bring 
  the 
  entire 
  

   horde 
  of 
  them 
  to 
  the 
  ground. 
  They 
  apijear 
  to 
  have 
  a 
  purpose 
  in 
  view 
  

   when 
  starting, 
  which, 
  if 
  interfered 
  with, 
  will 
  cause 
  much 
  uneasiness 
  on 
  

   their 
  part. 
  It 
  is 
  not 
  necessary 
  for 
  me 
  to 
  give 
  any 
  minute 
  description 
  

   of 
  the 
  general 
  laws 
  of 
  flight, 
  nor 
  to 
  dwell 
  upon 
  the 
  influence 
  of 
  storms, 
  

   changes 
  of 
  wind, 
  temperature, 
  elevation, 
  climate, 
  and 
  surface 
  configura- 
  

   tion 
  upon 
  these. 
  All 
  these 
  have 
  been 
  discussed 
  at 
  length 
  in 
  various 
  

   newsi)aper 
  articles 
  and 
  other 
  sketches 
  of 
  which 
  this 
  insect 
  with 
  its 
  his- 
  

   tory 
  formed 
  the 
  subject. 
  The 
  reports, 
  too, 
  of 
  the 
  United 
  States 
  Ento- 
  

   mological 
  Commission 
  are 
  exhaustive 
  on 
  this 
  portion 
  of 
  its 
  natural 
  

  

  