﻿846 
  ANNUAL, 
  REPOKT 
  SMITHSONIAN 
  INSTITUTION, 
  1922. 
  

  

  number 
  began 
  to 
  decrease 
  from 
  day 
  to 
  day, 
  till 
  by 
  the 
  end 
  of 
  a 
  week 
  

   all 
  had 
  departed. 
  

  

  When 
  the 
  mature 
  caterpillars 
  disappear 
  in 
  this 
  mysterious 
  man- 
  

   ner 
  they 
  go 
  off 
  to 
  spin 
  their 
  cocoons, 
  but 
  those 
  from 
  our 
  colonies 
  hid 
  

   themselves 
  so 
  effectively 
  for 
  this 
  act 
  that 
  few 
  of 
  them 
  were 
  recovered. 
  

   Two 
  cocoons 
  were 
  found 
  spun 
  against 
  the 
  under 
  side 
  of 
  a 
  wooden 
  

   bench 
  a 
  few 
  feet 
  from 
  where 
  the 
  12 
  caterpillars 
  spent 
  their 
  last 
  days 
  

   on 
  the 
  water 
  sprouts, 
  and 
  one 
  in 
  dry 
  grass 
  beneath. 
  Several 
  were 
  

   found 
  elsewhere 
  spun 
  vertically 
  amongst 
  blades 
  of 
  tall 
  grass, 
  one 
  

   was 
  taken 
  from 
  a 
  mass 
  of 
  cobwebs 
  on 
  the 
  floor 
  of 
  an 
  unused 
  chicken- 
  

   house, 
  and 
  another 
  from 
  the 
  rafters 
  of 
  an 
  open 
  shed. 
  It 
  is 
  usually 
  

   stated 
  that 
  the 
  tent 
  caterpillar 
  spins 
  its 
  cocoon 
  " 
  most 
  anywhere 
  " 
  

   amongst 
  grass 
  and 
  rubbish, 
  on 
  tree 
  trunks, 
  on 
  fences, 
  and 
  on 
  build- 
  

   ings. 
  But 
  Dr. 
  B. 
  A. 
  Porter 
  and 
  the 
  writer 
  made 
  a 
  thorough 
  search 
  

   in 
  the 
  neighborhood 
  of 
  six 
  tents 
  in 
  a 
  small 
  tree 
  beside 
  a 
  county 
  road 
  

   without 
  discovering 
  the 
  site 
  of 
  a 
  single 
  cocoon. 
  We 
  examined 
  the 
  

  

  surrounding 
  tall 
  grass 
  and 
  weeds, 
  

   turned 
  over 
  rocks 
  on 
  the 
  ground, 
  

   carefully 
  inspected 
  a 
  stone 
  wall 
  

   across 
  the 
  road, 
  and 
  examined 
  the 
  

   trunks 
  and 
  branches 
  of 
  near-by 
  

   trees. 
  

  

  The 
  caterpillars 
  that 
  left 
  the 
  

   fig. 
  io. 
  — 
  a 
  tent 
  caterpillar 
  cocoon 
  (natu- 
  two 
  colonies 
  in 
  the 
  yard 
  on 
  May 
  

   ral 
  8ize) 
  ' 
  19 
  were 
  captured 
  and 
  confined 
  in 
  

  

  an 
  outdoor 
  cage 
  where 
  they 
  were 
  daily 
  supplied 
  with 
  fresh 
  cherry 
  

   leaves. 
  All 
  of 
  these 
  spun 
  their 
  cocoons 
  in 
  the 
  cage 
  between 
  May 
  

   24 
  and 
  28, 
  and 
  from 
  this 
  we 
  may 
  infer 
  that 
  the 
  caterpillars 
  normally 
  

   spend 
  about 
  a 
  week 
  in 
  feeding 
  after 
  they 
  leave 
  the 
  tents. 
  Since 
  

   most 
  of 
  those 
  in 
  the 
  cage 
  had 
  molted 
  last 
  on 
  the 
  12th 
  or 
  13th, 
  they 
  

   were 
  from 
  12 
  to 
  16 
  days 
  in 
  the 
  last 
  stage 
  before 
  spinning 
  their 
  cocoons. 
  

   The 
  cocoon 
  is 
  a 
  slender 
  oval 
  or 
  almost 
  spindle-shaped 
  object, 
  the 
  

   larger 
  ones 
  being 
  about 
  an 
  inch 
  long 
  and 
  half 
  an 
  inch 
  wide 
  at 
  the 
  

   middle 
  (fig. 
  10). 
  The 
  cocoon 
  is 
  spun 
  of 
  white 
  silk 
  thread, 
  but 
  its 
  

   walls 
  are 
  stiffened 
  and 
  colored 
  by 
  a 
  yellow 
  substance 
  infiltrated 
  like 
  

   starch 
  all 
  through 
  the 
  meshes 
  of 
  the 
  web. 
  

  

  In 
  building 
  the 
  cocoon 
  the 
  caterpillar 
  first 
  spins 
  a 
  loose 
  network 
  

   of 
  threads 
  at 
  the 
  place 
  selected, 
  and 
  then, 
  using 
  this 
  for 
  a 
  support, 
  

   weaves 
  about 
  itself 
  the 
  walls 
  of 
  the 
  final 
  structure. 
  On 
  account 
  of 
  

   its 
  large 
  size, 
  as 
  compared 
  with 
  the 
  size 
  of 
  the 
  cocoon, 
  the 
  caterpillar 
  

   is 
  forced 
  to 
  double 
  on 
  itself 
  to 
  fit 
  its 
  self-imposed 
  cell. 
  Most 
  of 
  

   its 
  hairs, 
  however, 
  are 
  brushed 
  off 
  and 
  become 
  interlaced 
  with 
  the 
  

   threads 
  to 
  form 
  a 
  part 
  of 
  the 
  cocoon 
  fabric. 
  When 
  the 
  spinning 
  is 
  

   finished 
  the 
  caterpillar 
  ejects 
  a 
  yellowish, 
  pasty 
  liquid 
  from 
  its 
  intes- 
  

  

  