﻿PACKARD.] 
  IHE 
  LOCUST 
  EAST 
  OF 
  THE 
  PLAINS. 
  635 
  

  

  The 
  youDg 
  do 
  uot 
  leave 
  the 
  place 
  of 
  their 
  birth 
  until 
  after 
  the 
  first 
  

   mouth, 
  but 
  huddle 
  together, 
  uot 
  scattering, 
  as 
  most 
  youuginsects 
  do, 
  they 
  

   being 
  gregarious 
  at 
  the 
  outset. 
  The 
  small 
  bauds 
  then 
  unite 
  into 
  larger 
  

   ones, 
  and 
  these 
  mass 
  into 
  enormous 
  armies. 
  They 
  are 
  exceediugly 
  

   ravenous, 
  feeding 
  upon 
  each 
  other 
  when 
  other 
  food 
  is 
  exhausted. 
  

   Eiley 
  says 
  that 
  " 
  the 
  young 
  insects 
  move, 
  as 
  a 
  rule, 
  during 
  the 
  warmei 
  

   hours 
  of 
  the 
  day 
  only, 
  feeding, 
  if 
  hungry, 
  by 
  the 
  way, 
  but 
  generally 
  

   marching 
  in 
  a 
  given 
  direction 
  until 
  toward 
  evening.*^ 
  They 
  travel 
  in 
  

   schools 
  or 
  armies, 
  in 
  no 
  particular 
  direction, 
  but 
  purely 
  in' 
  search 
  of 
  

   food, 
  the 
  same 
  school 
  often 
  pursuing 
  a 
  different 
  course 
  one 
  day 
  to 
  that 
  

   pursued 
  the 
  day 
  previous." 
  In 
  Missouri, 
  the 
  young 
  moved 
  in 
  a 
  general 
  

   northerly 
  direction. 
  They 
  seldom 
  move, 
  when 
  half-grown, 
  " 
  at 
  a 
  greater 
  

   rate 
  thau 
  three 
  yards 
  a 
  minute, 
  even 
  when 
  at 
  their 
  greatest 
  speed, 
  over 
  

   a 
  tolerably 
  smooth 
  and 
  level 
  road, 
  and 
  not 
  halting 
  to 
  feed. 
  They 
  walk 
  

   three-fourths 
  of 
  this 
  distance 
  and 
  hop 
  the 
  rest." 
  It 
  is 
  in 
  the 
  young 
  

   wingless 
  condition 
  that 
  the 
  locust 
  is 
  most 
  to 
  be 
  feared, 
  and, 
  on 
  the 
  

   other 
  hand, 
  most 
  easily 
  subdued. 
  

  

  THE 
  ROCKY 
  MOUNTAIN 
  LOCUST 
  NOT 
  PERMANENTLY 
  ABUNDANT 
  AND 
  

   INJURIOUS 
  EAST 
  OF 
  THE 
  PLAINS. 
  

  

  It 
  has 
  been 
  abundantly 
  proved 
  by 
  Professor 
  Riley 
  and 
  others 
  that 
  the 
  

   locust 
  will 
  not 
  be 
  destructive 
  east 
  of 
  longitude 
  93° 
  or 
  94°, 
  namely, 
  the 
  

   western 
  edge 
  of 
  the 
  Mississippi 
  Valley. 
  We 
  have 
  seen 
  that 
  the 
  progeny 
  

   of 
  the 
  swarms 
  from 
  the 
  plains 
  lying 
  on 
  the 
  flanks 
  of 
  the 
  Eocky 
  

   Mountains 
  which 
  at 
  intervals 
  infest 
  the 
  western 
  border 
  of 
  the 
  Mis- 
  

   sissippi 
  basin 
  geuerally 
  return 
  northwestward. 
  The 
  cause 
  of 
  their 
  north- 
  

   westward 
  migration 
  is 
  in 
  all 
  probability 
  due 
  to 
  the 
  prevailing 
  southerly 
  

   and 
  easterly 
  winds 
  of 
  June 
  and 
  early 
  July 
  ; 
  but 
  those 
  that 
  are 
  left 
  are 
  

   said 
  to 
  be 
  enfeebled 
  and 
  degenerated. 
  Mr. 
  Riley 
  attributes 
  this 
  to 
  the 
  

   low 
  altitude 
  and 
  moisture 
  of 
  the 
  Mississippi 
  Valley, 
  the 
  locust 
  flourish- 
  

   ing 
  and 
  most 
  prolific 
  in 
  the 
  dry 
  elevated 
  plateaus 
  of 
  the 
  Rocky 
  Mount- 
  

   ains. 
  Professor 
  Riley 
  thinks 
  that 
  the 
  length 
  of 
  the 
  summers 
  of 
  the 
  

   western 
  Mississippi 
  States 
  as 
  compared 
  with 
  the 
  short 
  hot 
  summers 
  of 
  

   the 
  plains 
  another 
  cause 
  of 
  its 
  inability 
  to 
  live 
  permanently 
  east 
  of 
  the 
  

   plains 
  in 
  large 
  numbers. 
  To 
  use 
  Riley's 
  own 
  words 
  : 
  

  

  Assuming 
  that 
  I 
  have 
  correctly 
  placed 
  the 
  native 
  home 
  of 
  the 
  species 
  in 
  the 
  higher, 
  

   treeless, 
  and 
  uninhabitable 
  plains 
  of 
  the 
  Rocky 
  Mountain 
  region 
  of 
  the 
  northwest, 
  

   and 
  that 
  it 
  is 
  subalpiue, 
  we 
  may 
  perhaps 
  find, 
  in 
  addition 
  to 
  the 
  comparatively 
  sudden 
  

   chauo-e 
  from 
  an 
  attenuated 
  and 
  dry 
  to 
  a 
  more 
  dense 
  and 
  humid 
  atmosphere," 
  another 
  

   tangible 
  barrier 
  to 
  its 
  permanent 
  multiplication 
  in 
  the 
  more 
  fertile 
  country 
  to 
  the 
  

   southeast 
  in 
  the 
  lengthened 
  summer 
  season. 
  As 
  with 
  annual 
  plants, 
  so 
  with 
  insects 
  

   (like 
  this 
  locust), 
  which 
  produce 
  but 
  one 
  generation 
  annually, 
  and 
  whose 
  active 
  exist- 
  

   ence 
  is 
  bounded 
  by 
  the 
  spring 
  and 
  autumn 
  frosts, 
  the 
  duration 
  of 
  active 
  life 
  is 
  pro- 
  

   portioned 
  to 
  the 
  length 
  of 
  the 
  growing 
  season. 
  Hatching 
  late 
  and 
  developing 
  quickly 
  

   in 
  its 
  native 
  haunts, 
  our 
  Rocky 
  Mountain 
  locust, 
  when 
  born 
  within 
  our 
  borders 
  (and 
  

   the 
  same 
  will 
  apply 
  in 
  degi-ee 
  to 
  all 
  the 
  country 
  where 
  it 
  is 
  not 
  autochthonous), 
  is 
  in 
  

   the 
  condition 
  of 
  an 
  annual 
  northern 
  plant 
  sown 
  in 
  more 
  southern 
  climes; 
  and 
  just 
  as 
  

   this 
  attains 
  iirecocious 
  maturity 
  and 
  deteriorates 
  for 
  want 
  of 
  autumn's 
  ripening 
  in- 
  

   fluences, 
  so 
  our 
  locust 
  must 
  deteriorate 
  under 
  such 
  circumstances. 
  If 
  those 
  which 
  

   acquired 
  wings 
  in 
  Missouri 
  early 
  last 
  June 
  had 
  staid 
  with 
  us 
  long 
  enough 
  to 
  lay 
  eggs, 
  

   even 
  supposing 
  them 
  capable 
  of 
  doing 
  so, 
  these 
  eggs 
  would 
  have 
  inevitably 
  hatched 
  

   prematurely, 
  and 
  the 
  progeny 
  nnist 
  in 
  consequence 
  have 
  perished. 
  

  

  The 
  fact 
  that 
  some 
  changes 
  are 
  undergone 
  by 
  the 
  eastern 
  progeny 
  of 
  

   the 
  Rocky 
  Mountain 
  locust 
  is 
  substantiated 
  by 
  two 
  good 
  observers, 
  

   quoted 
  by 
  Mr. 
  Riley, 
  as 
  follows: 
  

  

  Mr. 
  Eiley 
  is 
  of 
  the 
  opinion 
  that 
  the 
  grasshoppers 
  run 
  out 
  in 
  a 
  few 
  generations 
  after 
  

   they 
  lea.ve 
  their 
  native 
  sandy 
  and 
  gravelly 
  soil. 
  My 
  experiments, 
  so 
  far 
  as 
  they 
  go- 
  

   verify 
  that 
  opinion. 
  For 
  several 
  years 
  I 
  have 
  caught 
  grasshoppers 
  during 
  early 
  "sum, 
  

  

  