﻿GENERAL 
  CONCLUSIONS. 
  41 
  

  

  of 
  that 
  which 
  was 
  infested 
  in 
  1905. 
  This 
  being 
  the 
  case, 
  the 
  oppor- 
  

   tunity 
  for 
  spread 
  has 
  greatly 
  increased, 
  and 
  as 
  the 
  insect 
  gradually 
  

   becomes 
  established 
  on 
  the 
  western 
  slope 
  of 
  the 
  high 
  lands 
  in 
  the 
  

   central 
  part 
  of 
  the 
  State, 
  the 
  opportunity 
  for 
  serious 
  damage 
  in 
  

   the 
  Connecticut 
  valley 
  is 
  rapidly 
  increasing. 
  

  

  In 
  connection 
  with 
  the 
  weather 
  record 
  given 
  for 
  this 
  period 
  it 
  is 
  

   interesting 
  to 
  note 
  the 
  corresponding 
  data 
  from 
  the 
  Weather 
  Bureau 
  

   stations 
  at 
  Portland, 
  Me., 
  and 
  at 
  Concord, 
  X. 
  H., 
  as 
  these 
  data 
  have 
  a 
  

   bearing 
  upon 
  the 
  spread 
  in 
  the 
  northern 
  part 
  of 
  the 
  territory. 
  

  

  GENERAL 
  SUMMARY. 
  

  

  The 
  map 
  and 
  wind 
  direction 
  records 
  give 
  a 
  fairly 
  good 
  idea 
  of 
  the 
  

   dispersion 
  of 
  the 
  gipsy 
  moth. 
  The 
  spread 
  has 
  been 
  along 
  the 
  lines 
  of 
  

   the 
  prevailing 
  winds 
  to 
  so 
  great 
  an 
  extent 
  that 
  the 
  evidence 
  is 
  con- 
  

   clusive 
  that 
  natural 
  spread 
  is 
  accomplished 
  chiefly 
  in 
  this 
  way. 
  All 
  

   the 
  records 
  bear 
  out 
  this 
  conclusion. 
  It 
  should 
  be 
  noted 
  in 
  the 
  Con- 
  

   cord 
  records 
  that 
  the 
  southeast 
  winds 
  were 
  the 
  ones 
  which 
  were 
  most 
  

   likely 
  to 
  carry 
  the 
  larvae 
  into 
  new 
  territory, 
  while 
  in 
  Portland 
  the 
  

   south 
  and 
  west 
  winds 
  which 
  predominated 
  would 
  do 
  the 
  same 
  thing 
  

   in 
  that 
  section. 
  It 
  should 
  be 
  remembered 
  that 
  neither 
  Concord, 
  N. 
  H., 
  

   nor 
  Portland, 
  Me., 
  has 
  been 
  badly 
  infested 
  and 
  that 
  the 
  spread 
  must 
  

   come 
  from 
  bad 
  colonies 
  nearer 
  the 
  center 
  of 
  infestation. 
  

  

  The 
  general 
  " 
  seeding 
  down 
  " 
  of 
  slightly 
  infested 
  territory 
  by 
  

   larvae 
  spread 
  by 
  the 
  wind 
  is 
  shown 
  in 
  some 
  detail 
  in 
  the 
  following 
  

   pages. 
  

  

  GENERAL 
  CONCLUSIONS. 
  

  

  It 
  is 
  impossible 
  to 
  give 
  a 
  detailed 
  explanation 
  of 
  the 
  cause 
  of 
  every 
  

   infestation. 
  The 
  weather 
  records 
  give 
  strong 
  evidence 
  that 
  the 
  wind 
  

   is 
  responsible 
  in 
  a 
  large 
  degree 
  for 
  the 
  spread 
  of 
  the 
  gipsy 
  moth, 
  but 
  

   the 
  spread 
  can 
  be 
  brought 
  about 
  only 
  under 
  the 
  favorable 
  conditions 
  

   which 
  have 
  already 
  been 
  explained. 
  The 
  present 
  apparatus 
  for 
  

   recording 
  wind 
  movements 
  is 
  somewhat 
  imperfect, 
  and 
  a^ 
  the 
  wind 
  

   is 
  usually 
  very 
  variable 
  it 
  is 
  probable 
  that 
  a 
  greater 
  local 
  spread 
  

   results 
  than 
  can 
  be 
  explained 
  from 
  wind 
  records. 
  Oilier 
  things 
  being 
  

   equal, 
  wind 
  spread 
  will 
  start 
  the 
  most 
  vigorous 
  colonies 
  nearest 
  the 
  

   bad 
  centers 
  of 
  infestation. 
  1 
  for 
  the 
  farther 
  the 
  caterpillars 
  are 
  carried 
  

   the 
  more 
  chance 
  there 
  is 
  for 
  them 
  to 
  become 
  widely 
  separated, 
  so 
  

  

  1 
  On 
  Mm.v 
  lit, 
  L912, 
  Mr. 
  C. 
  W. 
  Stockwell 
  found 
  thai 
  large 
  numbers 
  ol 
  Bret-stage 
  gipsj 
  

   moth 
  larviP 
  that 
  hatched 
  a 
  few 
  days 
  before 
  were 
  being 
  blown 
  from 
  an 
  Isolated 
  block 
  of 
  

   birches 
  into 
  a 
  pasture 
  by 
  a 
  Btrong 
  sonthwesl 
  wind. 
  At 
  a 
  point 
  125 
  feet 
  from 
  this 
  block 
  

   he 
  found 
  from 
  L'l 
  to 
  '21 
  larva- 
  per 
  square 
  foot 
  ; 
  tiny 
  wen- 
  crawling 
  about 
  on 
  the 
  grass 
  

   seeking 
  food. 
  On 
  the 
  posts 
  of 
  a 
  wire 
  fence, 
  L86 
  feel 
  from 
  the 
  birches, 
  over 
  500 
  larvwwere 
  

   found 
  on 
  each 
  post, 
  ami 
  smaller 
  numbers 
  <.r 
  larva- 
  were 
  found 
  at 
  a 
  greater 
  distance 
  

   away. 
  This 
  substantiates 
  tin- 
  experiments 
  previously 
  made, 
  ami 
  shows 
  what 
  happens 
  

   in 
  nature 
  under 
  favorable 
  conditions, 
  it 
  also 
  proves 
  that 
  tin- 
  heaviest 
  Infestations 
  

   brought 
  about 
  by 
  wind 
  spread 
  will 
  be 
  nearest 
  tin- 
  colony 
  from 
  which 
  the 
  larva 
  were 
  

   spread. 
  

  

  