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  THE 
  DISPERSION 
  OF 
  THE 
  GIPSY 
  MOTH. 
  

  

  tion 
  will 
  show 
  that 
  this 
  consists 
  of 
  silk 
  which 
  the 
  larva 
  has 
  spun, 
  

   and 
  it 
  is 
  probable 
  that 
  this 
  adds 
  to 
  the 
  buoyancy 
  of 
  the 
  insect 
  if 
  it 
  is 
  

   caught 
  up 
  by 
  the 
  wind. 
  

  

  As 
  the 
  method 
  of 
  using* 
  the 
  reel 
  gave 
  very 
  poor 
  results, 
  two 
  sets 
  

   of 
  experiments 
  were 
  carried 
  on 
  by 
  Mr. 
  C. 
  W. 
  Stockwell 
  in 
  the 
  lab- 
  

   oratory. 
  He 
  induced 
  the 
  caterpillars 
  to 
  spin, 
  and 
  attached 
  the 
  thread 
  

   to 
  the 
  end 
  of 
  a 
  stick 
  1 
  yard 
  long. 
  As 
  the 
  insect 
  lowered 
  itself, 
  the 
  

   thread 
  was 
  measured 
  with 
  the 
  stick 
  by 
  raising 
  and 
  inverting 
  it, 
  and 
  

   thus 
  the 
  larva 
  was 
  prevented 
  from 
  spinning 
  to 
  the 
  floor 
  of 
  the 
  room. 
  

   In 
  the 
  first 
  set 
  records 
  were 
  secured 
  from 
  18 
  newly 
  hatched 
  larvae 
  

   that 
  had 
  not 
  feci. 
  The 
  quantity 
  of 
  silk 
  spun 
  ranged 
  from 
  7 
  feet 
  6 
  

   inches 
  to 
  25 
  feet 
  6 
  inches, 
  averaging 
  17 
  feet. 
  Fourteen 
  records 
  were 
  

   then 
  secured 
  from 
  larvae 
  3 
  days 
  old, 
  and 
  the 
  silk 
  ranged 
  from 
  12 
  

   feet 
  to 
  63 
  feet 
  5 
  inches, 
  with 
  an 
  average 
  of 
  31 
  feet. 
  

  

  The 
  results 
  of 
  these 
  tests 
  show 
  that 
  there 
  is 
  much 
  individual 
  varia- 
  

   tion 
  in 
  the 
  quantity 
  of 
  silk 
  that 
  caterpillars 
  will 
  spin, 
  and 
  it 
  is 
  prob- 
  

   able 
  that 
  under 
  favorable 
  outdoor 
  conditions 
  much 
  more 
  would 
  

   be 
  produced 
  than 
  is 
  indicated 
  by 
  the 
  averages 
  given. 
  

  

  If 
  20 
  to 
  30 
  feet 
  of 
  silk 
  is 
  spun 
  by 
  a 
  larva 
  it 
  will 
  undoubtedly 
  help 
  

   it 
  to 
  remain 
  in 
  the 
  air 
  in 
  case 
  the 
  thread 
  is 
  broken 
  by 
  the 
  wind, 
  and 
  

   will 
  probably 
  add 
  buoyancy 
  to 
  the 
  insect 
  and 
  thus 
  increase 
  the 
  dis- 
  

   tance 
  that 
  would 
  ordinarily 
  be 
  covered 
  by 
  wind 
  spread. 
  

  

  RELATION 
  OF 
  TEMPERATURE 
  TO 
  HATCHING 
  OF 
  EGGS. 
  

  

  Temperature 
  has 
  a 
  very 
  important 
  relation 
  to 
  the 
  hatching 
  of 
  

   insect 
  eggs; 
  hence 
  the 
  time 
  of 
  larval 
  appearance 
  varies 
  from 
  year 
  to 
  

   year. 
  Gipsy-moth 
  eggs 
  begin 
  to 
  hatch 
  the 
  last 
  week 
  in 
  April, 
  but 
  

   the 
  hatching 
  is 
  often 
  deferred 
  a 
  week 
  or 
  more. 
  Owing 
  to 
  the 
  warm 
  

   weather 
  in 
  March, 
  1910, 
  hatching 
  took 
  place 
  in 
  the 
  field 
  as 
  early 
  as 
  

   April 
  3, 
  but 
  the 
  bulk 
  of 
  the 
  eggs 
  did 
  not 
  hatch-until 
  much 
  later. 
  In 
  

   the 
  case 
  of 
  the 
  gipsy 
  moth 
  — 
  and 
  the 
  same 
  principle 
  governs 
  in 
  the 
  

   case 
  of 
  other 
  insects 
  which 
  winter 
  in 
  the 
  egg 
  form 
  — 
  it 
  is 
  possible 
  to 
  

   secure 
  hatching 
  in 
  the 
  winter 
  if 
  the 
  eggs 
  are 
  kept 
  in 
  a 
  warm 
  room. 
  

   The 
  length 
  of 
  the 
  period 
  of 
  high 
  temperature 
  which 
  is 
  required 
  to 
  

   hatch 
  them 
  varies 
  with 
  the 
  season 
  of 
  the 
  year. 
  For 
  example, 
  gipsy- 
  

   moth 
  eggs 
  collected 
  late 
  in 
  December 
  and 
  kept 
  at 
  a 
  temperature 
  of 
  

   from 
  70° 
  F. 
  to 
  80° 
  F. 
  will 
  hatch 
  in 
  about 
  15 
  days, 
  while 
  if 
  the 
  

   same 
  collection 
  is 
  made 
  in 
  March 
  hatching 
  will 
  take 
  place 
  in 
  about 
  

   half 
  the 
  time. 
  This 
  shows 
  that 
  as 
  the 
  normal 
  time 
  for 
  hatching 
  ap- 
  

   proaches 
  it 
  requires 
  a 
  shorter 
  period 
  of 
  warm 
  weather 
  to 
  bring 
  out 
  

   the 
  larva 
  1 
  . 
  

  

  During 
  the 
  past 
  four 
  years 
  the 
  first 
  date 
  of 
  finding 
  gipsy-moth 
  

   larvae 
  in 
  the 
  field 
  in 
  Massachusetts 
  was, 
  in 
  1908, 
  April 
  22 
  ; 
  1909, 
  April 
  

   22; 
  1910, 
  April 
  3; 
  1911, 
  April 
  28. 
  The 
  data 
  for 
  1908 
  were 
  furnished 
  

   by 
  Mr. 
  W. 
  F. 
  Fiske. 
  The 
  other 
  dates 
  were 
  secured 
  from 
  field 
  reports 
  

  

  