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  ANNUAL, 
  REPORT 
  SMITHSONIAN 
  INSTITUTION, 
  1922. 
  

  

  simply 
  go 
  down 
  the 
  trunks 
  of 
  the 
  trees 
  and 
  walk 
  away. 
  But 
  no 
  ; 
  once 
  

   in 
  their 
  lives 
  they 
  must 
  have 
  a 
  dramatic 
  moment. 
  A 
  caterpillar 
  

   comes 
  rushing 
  out 
  of 
  a 
  tent 
  as 
  if 
  suddenly 
  awakened 
  from 
  some 
  ter- 
  

   rible 
  dream 
  or 
  as 
  if 
  pursued 
  by 
  a 
  demon, 
  hurries 
  outward 
  along 
  a 
  

   branch, 
  goes 
  to 
  the 
  end 
  of 
  a 
  spur 
  or 
  the 
  tip 
  of 
  a 
  leaf, 
  and 
  without 
  

   slackening 
  continues 
  out 
  into 
  space 
  till 
  the 
  end 
  of 
  the 
  support 
  tickles 
  

   his 
  stomach, 
  when 
  suddenly 
  he 
  gives 
  a 
  flip 
  into 
  the 
  air, 
  turns 
  a 
  

   somersault, 
  and 
  lands 
  on 
  the 
  ground. 
  (Fig. 
  9.) 
  

  

  The 
  first 
  performance 
  of 
  this 
  sort 
  was 
  observed 
  on 
  May 
  15. 
  On 
  the 
  

   afternoon 
  of 
  the 
  19th, 
  20 
  or 
  more 
  caterpillars 
  from 
  two 
  neighboring 
  

   colonies 
  were 
  seen 
  leaving 
  the 
  trees 
  in 
  the 
  same 
  fashion 
  within 
  half 
  

   an 
  hour. 
  Most 
  of 
  the 
  members 
  of 
  one 
  of 
  these 
  colonies 
  had 
  their 
  last 
  

   molt 
  on 
  May 
  12 
  and 
  13. 
  During 
  the 
  next 
  few 
  days 
  other 
  caterpillars 
  

   were 
  observed 
  jumping 
  from 
  four 
  trees 
  containing 
  colonies 
  under 
  

   observation. 
  All 
  of 
  these 
  went 
  off 
  individually 
  at 
  various 
  times, 
  but 
  

  

  most 
  of 
  them 
  early 
  in 
  the 
  after- 
  

   noon. 
  Many 
  caterpillars 
  simply 
  

   drop 
  off 
  when 
  they 
  reach 
  the 
  end 
  

   of 
  the 
  branch, 
  without 
  the 
  acro- 
  

   batic 
  touch, 
  but 
  only 
  three 
  were 
  

   seen 
  to 
  go 
  down 
  the 
  trunk 
  of 
  a 
  

   tree 
  in 
  commonplace 
  style. 
  

  

  The 
  population 
  of 
  the 
  tents 
  

   gradually 
  decreases 
  during 
  sev- 
  

   eral 
  days 
  following 
  the 
  time 
  when 
  

   the 
  first 
  caterpillar 
  departs. 
  One 
  

   of 
  the 
  two 
  tents 
  from 
  which 
  the 
  

   general 
  exodus 
  was 
  noted 
  on 
  May 
  19 
  was 
  opened 
  on 
  the 
  21st 
  and 
  was 
  

   found 
  to 
  contain 
  only 
  one 
  remaining 
  caterpillar. 
  On 
  the 
  evening 
  of 
  

   the 
  22d 
  a 
  solitary 
  individual 
  was 
  out 
  feeding 
  from 
  the 
  other 
  tent. 
  

   The 
  two 
  younger 
  colonies 
  maintained 
  their 
  numbers 
  till 
  the 
  22d, 
  

   after 
  which 
  they 
  diminished 
  till, 
  within 
  a 
  few 
  days, 
  they 
  too 
  were 
  

   deserted. 
  The 
  members 
  of 
  all 
  these 
  colonies 
  hatched 
  from 
  the 
  eggs 
  

   on 
  April 
  8, 
  9, 
  and 
  10, 
  so 
  seven 
  weeks 
  is 
  the 
  greatest 
  length 
  of 
  time 
  

   that 
  any 
  of 
  them 
  spent 
  on 
  the 
  trees 
  of 
  their 
  birth. 
  The 
  caterpillar 
  

   that 
  left 
  the 
  tent 
  on 
  the 
  15th 
  came 
  from 
  a 
  colony 
  that 
  began 
  to 
  hatch 
  

   on 
  April 
  10, 
  giving 
  an 
  observed 
  minimum 
  of 
  36 
  days. 
  

  

  As 
  soon 
  as 
  a 
  departing 
  caterpillar 
  lands 
  on 
  the 
  ground 
  it 
  sets 
  off 
  

   at 
  a 
  rapid 
  pace 
  as 
  if 
  it 
  had 
  already 
  picked 
  out 
  its 
  destination 
  and 
  

   knew 
  what 
  road 
  to 
  take. 
  Early 
  in 
  the 
  afternoon 
  of 
  May 
  21 
  a 
  cater- 
  

   pillar 
  was 
  observed 
  making 
  its 
  headlong 
  rush 
  from 
  the 
  tent 
  of 
  one 
  

   of 
  the 
  later 
  colonies. 
  It 
  jumped 
  from 
  the 
  southeast 
  side 
  of 
  the 
  tree 
  

   and, 
  without 
  hesitation, 
  started 
  off 
  at 
  a 
  running 
  gait 
  in 
  the 
  same 
  di- 
  

   rection. 
  Its 
  course 
  took 
  it 
  first 
  across 
  a 
  narrow 
  strip 
  of 
  grass, 
  then 
  

  

  Fig. 
  9. 
  — 
  A 
  tent 
  caterpillar 
  in 
  the 
  last 
  

   stage 
  leaving 
  the 
  tree 
  hy 
  jumping 
  from 
  

   the 
  end 
  of 
  a 
  twig 
  to 
  the 
  ground. 
  

  

  