﻿114 
  REPORT 
  UNITED 
  STATES 
  ENTOMOLOGICAL 
  COMMISSION. 
  

  

  Sudden 
  appearance 
  and 
  disappearance. 
  — 
  " 
  Among 
  the 
  manifes- 
  

   tations 
  in 
  lower 
  animal 
  life, 
  few 
  are 
  more 
  astonishing 
  than 
  the 
  sud- 
  

   den 
  occurrence 
  of 
  a 
  species 
  in 
  vast 
  numbers 
  over 
  large 
  stretches 
  of 
  

   country, 
  and 
  its 
  as 
  sudden 
  disappearance. 
  In 
  a 
  few 
  rare 
  instances, 
  

   as 
  with 
  the 
  thirteen 
  and 
  seventeen 
  year 
  Cicadas, 
  these 
  manifestations 
  

   are 
  strictly 
  periodical, 
  and 
  occur 
  at 
  regular 
  intervals 
  5 
  but 
  in 
  the 
  great 
  

   majority 
  of 
  instances 
  they 
  have 
  no 
  such 
  periodicity. 
  The 
  numerous 
  

   natural 
  checks 
  which 
  surround 
  every 
  animal, 
  added 
  to 
  the 
  meteorologi- 
  

   cal 
  conditions 
  which 
  affect 
  it 
  in 
  its 
  struggle 
  for 
  existence, 
  sufQciently 
  

   explain 
  these 
  phenomena 
  to 
  the 
  intelligent 
  naturalist, 
  though 
  it 
  is 
  not 
  

   always 
  easy 
  to 
  point 
  out 
  facts 
  in 
  specific 
  cases. 
  Under 
  the 
  head 
  of 
  

   * 
  Habits 
  of 
  the 
  Worm 
  ', 
  I 
  have 
  already 
  given 
  the 
  reasons 
  why 
  it 
  escapes 
  

   attention 
  in 
  its 
  earlier 
  stages 
  and 
  in 
  seasons 
  when 
  it 
  is 
  not 
  excessively 
  

   abundant. 
  " 
  Hidden 
  at 
  the 
  base 
  of 
  tufts 
  of 
  rank 
  grass 
  and 
  feeding 
  only 
  

   at 
  night, 
  it 
  may 
  live 
  for 
  generation 
  after 
  generation, 
  while 
  the 
  unsus- 
  

   pecting 
  .farmer 
  little 
  imagines 
  that 
  his 
  dreaded 
  enemy 
  is 
  so 
  near. 
  If 
  

   there 
  should 
  come 
  one 
  or 
  more 
  seasons 
  of 
  drought, 
  however, 
  — 
  weather 
  

   extremely 
  favorable 
  to 
  the 
  increase 
  of 
  the 
  worms, 
  — 
  they 
  begin 
  to 
  multiply 
  

   I)rodigiously5 
  large 
  numbers 
  hibernate, 
  and 
  in 
  the 
  ensuing 
  spring 
  multi- 
  

   tudes 
  of 
  moths 
  fly 
  out 
  over 
  the 
  country, 
  each 
  filled 
  with 
  her 
  seven 
  or 
  

   eight 
  hundred 
  eggs 
  with 
  which 
  to 
  stock 
  the 
  surrounding 
  pastures 
  and 
  

   grain 
  fields. 
  The 
  young 
  worms 
  hatching 
  from 
  these 
  eggs 
  and 
  feeding 
  

   in 
  their 
  normal 
  cut- 
  worm 
  manner 
  still 
  escape 
  the 
  eyes 
  of 
  the 
  farmer; 
  

   *' 
  but 
  when 
  the 
  bulk 
  of 
  them 
  have 
  passed 
  through 
  the 
  last 
  molt, 
  or, 
  in 
  other 
  

   words, 
  are 
  nearly 
  full-grown, 
  and 
  have 
  stripped 
  the 
  fields 
  in 
  which 
  they 
  

   were 
  born, 
  they 
  are 
  then 
  obliged 
  to 
  migrate 
  in 
  bodies 
  to 
  new 
  pastures. 
  

   Thus 
  assembled 
  and 
  exposed, 
  they 
  pass 
  through 
  grass 
  and 
  grain 
  fields, 
  de- 
  

   vouring 
  as 
  they 
  go 
  j 
  for 
  they 
  are 
  now 
  exceedingly 
  voracious, 
  and, 
  like 
  most 
  

   Lepidopterous 
  larvae, 
  consume 
  more 
  during 
  the 
  last 
  few 
  days 
  of 
  worm-life 
  

   than 
  during 
  all 
  the 
  rest 
  of 
  their 
  existence. 
  The 
  farmer 
  who 
  is 
  unfamiliar 
  

   with 
  their 
  life-habits 
  wonders 
  where 
  they 
  come 
  from 
  so 
  suddenly, 
  and 
  pre- 
  

   sently, 
  when 
  they 
  enter 
  the 
  earth 
  to 
  transform, 
  he 
  wonders 
  again 
  where 
  

   they 
  go 
  to. 
  In 
  these 
  exposed 
  numbers, 
  also, 
  the 
  numerous 
  natural 
  ene- 
  

   mies 
  of 
  the 
  worms 
  congregate 
  about 
  them 
  and 
  do 
  their 
  murderous 
  work 
  

   far 
  more 
  effectively 
  thau 
  when 
  they 
  have 
  to 
  seek 
  individuals 
  hidden 
  here 
  

   and 
  there 
  in 
  rank 
  grass; 
  so 
  that 
  we 
  cease 
  to 
  wonder 
  at 
  the 
  almost 
  total 
  

   annihilation 
  of 
  the 
  species 
  the 
  year 
  following 
  ^ts 
  advent 
  in 
  such 
  num- 
  

   bers." 
  

  

  Dr. 
  Fitch, 
  in 
  his 
  sixth 
  report, 
  proposed 
  a 
  theory 
  to 
  account 
  for 
  these 
  

   seemingly 
  unaccountable 
  appearances 
  of 
  the 
  worms, 
  which, 
  first 
  and 
  last, 
  

   has 
  caused 
  much 
  discussion. 
  In 
  his 
  own 
  words 
  it 
  is 
  stated 
  as 
  follows: 
  

  

  The 
  spring 
  and 
  early 
  summer 
  of 
  this 
  year 
  [1861] 
  was 
  exactly 
  the 
  reverse 
  of 
  last 
  year 
  

   — 
  unusually 
  wet, 
  and 
  the 
  water 
  high 
  in 
  all 
  our 
  streams. 
  Hereby 
  the 
  swamps 
  have 
  

   all 
  been 
  overflowed, 
  and 
  this 
  insect 
  has 
  been 
  drowned 
  out 
  of 
  them. 
  The 
  moths 
  or 
  

   millers 
  on 
  coming 
  out 
  of 
  their 
  chrysalides, 
  found 
  it 
  was 
  impossible 
  for 
  them 
  to 
  get 
  to 
  

   the 
  roots 
  of 
  the 
  grass 
  there, 
  to 
  deposit 
  their 
  eggs. 
  They 
  were 
  obliged 
  to 
  forsake 
  their 
  

   usual 
  haunts 
  and 
  scatter 
  themselves 
  out 
  over 
  the 
  country, 
  the 
  incessant 
  rains 
  making 
  

  

  