﻿20 
  THE 
  DISPERSION 
  OF 
  THE 
  GIPSY 
  MOTH. 
  

  

  on 
  the 
  screens 
  as 
  a 
  result 
  of 
  this 
  liberation. 
  When 
  the 
  experiments 
  

   were 
  started 
  it 
  was 
  planned 
  to 
  examine 
  thoroughly 
  a 
  few 
  willow 
  

   sprouts, 
  which 
  were 
  growing 
  along 
  the 
  race 
  track 
  not 
  far 
  from 
  the 
  

   water 
  tower, 
  but 
  on 
  account 
  of 
  the 
  pressure 
  of 
  other 
  work 
  this 
  was 
  

   neglected. 
  In 
  making 
  an 
  examination 
  of 
  the 
  screens 
  May 
  28 
  it 
  was 
  

   found 
  that 
  several 
  old 
  egg 
  clusters 
  and 
  a 
  considerable 
  number 
  of 
  

   caterpillars 
  were 
  present 
  on 
  a 
  clump 
  of 
  willow 
  sprouts 
  about 
  25 
  feet 
  

   from 
  the 
  screen 
  on 
  the 
  west 
  side 
  of 
  the 
  tower. 
  In 
  spite 
  of 
  this, 
  how- 
  

   ever, 
  no 
  caterpillars 
  were 
  found 
  on 
  this 
  screen 
  during 
  the 
  season. 
  

   There 
  is 
  a 
  bare 
  possibility 
  that 
  the 
  caterpillar 
  found 
  on 
  the 
  screen 
  

   on 
  the 
  opposite 
  side 
  of 
  the 
  tower 
  may 
  have 
  come 
  from 
  some 
  of 
  these 
  

   willow 
  sprouts, 
  but 
  it 
  is 
  doubtful 
  whether 
  this 
  is 
  the 
  case. 
  The 
  

   screens 
  were 
  removed 
  June 
  13 
  and 
  examined 
  at 
  the 
  laboratory 
  in 
  

   the 
  same 
  manner 
  as 
  those 
  already 
  mentioned, 
  but 
  no 
  other 
  cater- 
  

   pillars 
  were 
  found. 
  

  

  The 
  foregoing 
  experiments 
  were 
  carried 
  on 
  under 
  natural 
  condi- 
  

   tions 
  and 
  on 
  a 
  large 
  scale, 
  and 
  in 
  addition 
  two 
  other 
  tests 
  were 
  made 
  

   by 
  Mr. 
  Mosher. 
  One 
  large 
  screen 
  was 
  built 
  in 
  the 
  form 
  of 
  a 
  cross, 
  

   the 
  same 
  as 
  the 
  one 
  placed 
  on 
  the 
  tower 
  at 
  Mount 
  Gilead. 
  It 
  was 
  set 
  

   up 
  on 
  land 
  at 
  Manchester, 
  Mass., 
  where 
  the 
  forest 
  had 
  recently 
  been 
  cut. 
  

   Large 
  trees 
  surrounding 
  this 
  area 
  were 
  badly 
  infested 
  with 
  the 
  gipsy 
  

   moth, 
  and 
  some 
  additional 
  data 
  Avould 
  probabh 
  7 
  have 
  been 
  secured 
  

   from 
  this 
  experiment 
  if 
  a 
  forest 
  fire 
  had 
  not 
  run 
  through 
  the 
  area 
  

   Avhere 
  it 
  was 
  conducted. 
  

  

  Another 
  raft 
  was 
  constructed 
  at 
  Chebacco 
  Lake 
  in 
  Essex, 
  Mass., 
  

   similar 
  to 
  the 
  one 
  used 
  at 
  Sandy 
  Pond, 
  but 
  owing 
  to 
  bad 
  weather 
  and 
  

   high 
  winds 
  it 
  was 
  impossible 
  to 
  anchor 
  it 
  securely 
  in 
  the 
  center 
  of 
  

   the 
  lake 
  until 
  it 
  was 
  too 
  late 
  to 
  secure 
  the 
  data 
  desired 
  in 
  the 
  experi- 
  

   ment. 
  Before 
  these 
  tests 
  had 
  been 
  carried 
  very 
  far 
  it 
  appeared 
  

   desirable 
  to 
  check 
  up 
  the 
  results 
  in 
  a 
  more 
  definite 
  way, 
  and 
  in 
  order 
  

   to 
  do 
  this 
  a 
  series 
  of 
  experiments 
  were 
  planned, 
  which 
  were 
  carried 
  

   on 
  by 
  Mr. 
  C. 
  W. 
  Collins 
  and 
  the 
  writer 
  on 
  the 
  salt 
  marshes 
  (PI. 
  IX) 
  

   between 
  Lynn 
  and 
  Revere, 
  Mass. 
  

  

  EXPERIMENTS 
  ON 
  LYNN 
  MARSHES, 
  MASS. 
  

  

  A 
  box 
  of 
  egg 
  clusters 
  containing 
  many 
  newly 
  hatched 
  larvae 
  was 
  

   attached 
  to 
  the 
  top 
  of 
  a 
  pole 
  about 
  6 
  feet 
  from 
  the 
  ground. 
  This 
  

   point 
  was 
  used 
  as 
  a 
  central 
  station 
  and 
  was 
  half 
  a 
  mile 
  or 
  more 
  from 
  

   any 
  tree 
  or 
  tree 
  growth. 
  One 
  end 
  of 
  the 
  box 
  (PL 
  IX, 
  fig. 
  1), 
  con- 
  

   taining 
  the 
  egg 
  clusters 
  and 
  caterpillars, 
  was 
  partly 
  cut 
  away 
  with 
  a 
  

   knife, 
  while 
  in 
  the 
  other 
  a 
  small 
  hole 
  was 
  made 
  to 
  allow 
  the 
  wind 
  to 
  

   blow 
  through 
  the 
  bpx. 
  Small 
  screens, 
  2 
  feet 
  wide 
  and 
  G 
  to 
  8 
  feet 
  

   long 
  (PL 
  X), 
  were 
  attached 
  to 
  stakes 
  which 
  were 
  sharpened 
  so 
  that 
  

   they 
  could 
  be 
  pressed 
  into 
  the 
  ground; 
  so 
  that 
  when 
  these 
  screens 
  

   were 
  set 
  up 
  they 
  were 
  about 
  5 
  feet 
  above 
  the 
  ground. 
  They 
  were 
  

  

  