﻿74 
  REPORT 
  UNITED 
  STATES 
  ENTOMOLOGICAL 
  COMMISSION. 
  

  

  Our 
  somewhat 
  full, 
  though 
  far 
  from 
  complete, 
  account 
  of 
  flights 
  in 
  our 
  

   First 
  Eeport 
  will 
  render 
  it 
  unnecessary 
  to 
  state 
  much 
  that 
  might 
  appear 
  

   to 
  be 
  required 
  in 
  a 
  full 
  discussion 
  of 
  locust 
  migrations 
  ; 
  we 
  therefore 
  refer 
  

   the 
  reader 
  to 
  that 
  report 
  to 
  fill 
  out 
  such 
  lacunse 
  as 
  appear 
  here. 
  

  

  In 
  studying 
  the 
  subject 
  of 
  flights, 
  we 
  have 
  found 
  it 
  convenient 
  not 
  

   only 
  to 
  note 
  such 
  points 
  or 
  subdivisions 
  as 
  the 
  mode 
  of 
  flight, 
  direction 
  

   of 
  flight, 
  density 
  and 
  extent 
  of 
  swarms, 
  distance 
  over 
  which 
  they 
  move,, 
  

   date 
  of 
  flights, 
  hours 
  of 
  rising 
  and 
  alighting, 
  the 
  height 
  at 
  which 
  they 
  

   fly, 
  rate 
  of 
  movement, 
  meteorological 
  influences, 
  as 
  effect 
  of 
  wind, 
  rain, 
  

   heat, 
  &c, 
  flights 
  at 
  night, 
  cause 
  of 
  flights, 
  &c. 
  ; 
  but 
  also, 
  in 
  the 
  case 
  of 
  

   our 
  locust, 
  to 
  distinguish 
  between 
  invading 
  swarms, 
  returning 
  swarms, 
  

   and 
  local 
  flights. 
  As 
  we 
  may 
  have 
  occasion 
  to 
  make 
  frequent 
  use 
  of 
  the 
  

   latter 
  terms, 
  we 
  will 
  explain 
  them 
  first, 
  adding, 
  at 
  the 
  same 
  time, 
  what 
  

   we 
  may 
  have 
  to 
  say 
  in 
  reference 
  thereto. 
  

  

  1. 
  DIRECTION 
  OF 
  MOVEMENTS. 
  

  

  A 
  careful 
  study 
  of 
  the 
  migrations 
  of 
  the 
  Eocky 
  Mountain 
  locust 
  for 
  

   some 
  years 
  past 
  has 
  revealed 
  the 
  fact 
  that 
  the 
  general 
  or 
  combined 
  

   movements 
  of 
  this 
  species, 
  so 
  far 
  as 
  the 
  direction 
  or 
  course 
  is 
  concerned,, 
  

   may 
  be 
  designated 
  by 
  the 
  three 
  terms, 
  Invading 
  swarms, 
  Eeturning: 
  

   swarms, 
  and 
  Local 
  flights. 
  

  

  a. 
  Invading 
  swarms. 
  — 
  This 
  term, 
  when 
  used 
  with 
  reference 
  to 
  the 
  

   movements 
  of 
  G. 
  spretus 
  east 
  of 
  the 
  mountains, 
  applies 
  to 
  those 
  swarms- 
  

   or 
  hordes 
  which 
  move 
  down 
  from 
  their 
  native 
  hatching 
  grounds 
  in 
  the 
  

   west 
  and 
  northwest 
  into 
  those 
  sections 
  where 
  they 
  are 
  not 
  in 
  any 
  sense 
  

   permanent 
  residents. 
  It 
  is 
  only 
  applied 
  to 
  those 
  which, 
  leaving 
  the 
  

   permanent 
  area, 
  pass 
  across 
  its 
  boundary 
  into 
  the 
  temporary 
  regions- 
  

   shown 
  in 
  our 
  map. 
  

  

  The 
  facts 
  showing 
  that 
  the 
  swarms 
  which 
  invade 
  the 
  temporary 
  region 
  

   come 
  from 
  the 
  permanent 
  regions 
  of 
  the 
  west 
  and 
  northwest 
  are 
  so 
  nu- 
  

   merous 
  and 
  have 
  been 
  so 
  fully 
  presented 
  in 
  our 
  former 
  report 
  that 
  it 
  is 
  

   unnecessary 
  for 
  us 
  to 
  dwell 
  on 
  them 
  at 
  any 
  length 
  at 
  this 
  time, 
  as 
  we 
  

   have 
  but 
  little 
  to 
  add 
  that 
  is 
  new 
  in 
  reference 
  thereto. 
  It 
  is 
  true 
  that 
  

   but 
  few 
  swarms 
  have 
  been 
  traced 
  from 
  their 
  points 
  of 
  departure 
  in 
  the 
  

   permanent 
  regions 
  to 
  their 
  stopping 
  places 
  in 
  the 
  temporary 
  section 
  r, 
  

   yet 
  the 
  circumstantial 
  evidence 
  is 
  so 
  strong 
  as 
  to 
  no 
  longer 
  admit 
  of 
  any 
  

   reasonable 
  doubt. 
  

  

  This 
  evidence 
  may 
  be 
  briefly 
  summarized 
  as 
  follows 
  : 
  

  

  First. 
  That 
  the 
  invading 
  swarms, 
  especially 
  in 
  years 
  when 
  eggs 
  have 
  

   not 
  been 
  deposited 
  the 
  previous 
  season, 
  are 
  very 
  generally, 
  if 
  not 
  always,, 
  

   observed 
  in 
  the 
  temporary 
  region 
  east 
  of 
  the 
  mountains 
  to 
  come 
  from 
  

   the 
  west 
  or 
  northwest, 
  usually 
  from 
  the 
  latter 
  direction. 
  The 
  following 
  

   brief 
  summary 
  from 
  our 
  former 
  report 
  m 
  is 
  strongly 
  corroborative 
  of 
  this 
  

   assertion 
  : 
  

  

  1821. 
  — 
  Swarms 
  of 
  locusts 
  entered 
  Missouri 
  from 
  the 
  northwest. 
  

   1864. 
  — 
  Swarms 
  entered 
  Iowa 
  and 
  Minnesota 
  from 
  the 
  northwest. 
  

  

  171 
  Page 
  148 
  et 
  seq. 
  

  

  