﻿221 
  

  

  of 
  August, 
  and 
  most 
  of 
  them 
  hibernated 
  before 
  the 
  second 
  moult, 
  as 
  

   the 
  temperature 
  of 
  the 
  nights 
  and 
  early 
  mornings 
  fell 
  sometimes 
  to 
  

   freezing 
  point 
  even 
  in 
  the 
  first 
  half 
  of 
  August. 
  The 
  caterpillars 
  

   appeared 
  again 
  on 
  the 
  trees 
  in 
  the 
  first 
  half 
  of 
  the 
  next 
  May, 
  but 
  just 
  

   after 
  their 
  appearance 
  they 
  take 
  little 
  food. 
  The 
  feeding 
  increases 
  

   gradually, 
  and 
  the 
  maximum 
  damage 
  to 
  the 
  trees 
  takes 
  place 
  in 
  June 
  

   and 
  July, 
  when 
  a 
  caterpillar 
  may 
  devour 
  in 
  a 
  few 
  minutes 
  a 
  whole 
  

   fir 
  needle 
  ; 
  during 
  this 
  time 
  the 
  caterpillars 
  more 
  than 
  double 
  their 
  

   size. 
  In 
  August 
  the 
  feeding 
  decreases 
  again, 
  although 
  the 
  cate: 
  pillars 
  

   still 
  remain 
  on 
  the 
  trees, 
  passing 
  to 
  the 
  second 
  wintering 
  in 
  September. 
  

   Hibernation 
  takes 
  place 
  in 
  both 
  cases 
  under 
  moss 
  in 
  the 
  "taiga." 
  

   After 
  the 
  second 
  winter 
  the 
  larvae 
  appear 
  again 
  in 
  April, 
  feeding 
  till 
  

   early 
  in 
  June, 
  when 
  they 
  pupate, 
  producing 
  moths 
  in 
  the 
  same 
  month. 
  

   The 
  author 
  goes 
  on 
  to 
  deal 
  with 
  the 
  importance 
  of 
  D. 
  pini 
  in 
  the 
  

   economy 
  of 
  forests, 
  describing 
  the 
  nature 
  and 
  consequences 
  of 
  the 
  

   damage 
  done, 
  the 
  selection 
  of 
  plantations 
  by 
  the 
  females 
  for 
  oviposi- 
  

   tion, 
  the 
  methods 
  of 
  migration 
  of 
  the 
  caterpillars, 
  and 
  the 
  geographical 
  

   distribution 
  of 
  the 
  pests. 
  It 
  often 
  happens 
  that 
  numbers 
  of 
  the 
  larvae 
  

   perish 
  through 
  not 
  being 
  able 
  to 
  find 
  food 
  in 
  the 
  woods 
  laid 
  bare 
  by 
  the 
  

   preceding 
  generations 
  ; 
  moreover, 
  the 
  denudation 
  of 
  the 
  crowns 
  of 
  

   the 
  trees 
  also 
  caused 
  the 
  pupae 
  to 
  perish, 
  owing 
  to 
  the 
  excessive 
  heat 
  

   of 
  the 
  sun's 
  rays, 
  coupled 
  with 
  the 
  loss 
  of 
  moisture. 
  The 
  bare 
  crowns 
  

   favour 
  also 
  the 
  activities 
  of 
  various 
  parasites, 
  and 
  the 
  number 
  of 
  

   caterpillars 
  infested 
  by 
  them 
  in 
  such 
  trees 
  is 
  much 
  larger 
  than 
  in 
  trees 
  

   with 
  needles 
  on 
  them. 
  While 
  D. 
  pini 
  prefers 
  pine 
  trees, 
  which 
  provide 
  

   its 
  principal 
  food, 
  D. 
  segregatus 
  avoids 
  these 
  trees, 
  and 
  the 
  author 
  

   states 
  that 
  he 
  has 
  even 
  seen 
  single 
  pines 
  or 
  groups 
  of 
  pines 
  unattacked 
  

   or 
  only 
  shghtly 
  damaged, 
  w^hile 
  all 
  the 
  trees 
  round 
  them 
  (firs, 
  cedars, 
  

   larches) 
  were 
  entirely 
  stripped 
  by 
  the 
  larvae. 
  In 
  the 
  government 
  of 
  

   Irkutsk 
  the 
  principal 
  food 
  of 
  these 
  insects 
  is 
  provided 
  by 
  firs, 
  Siberian 
  

   firs 
  and 
  cedars, 
  while 
  in 
  some 
  parts 
  of 
  the 
  government 
  of 
  Ufa 
  D. 
  

   segregatus 
  damages 
  principally 
  larch 
  trees. 
  The 
  caterpillars 
  attack 
  

   mostly 
  old 
  cedar 
  woods 
  or 
  " 
  taiga 
  " 
  forests 
  (100-150 
  years 
  old) 
  which 
  

   form 
  the 
  greater 
  part 
  of 
  the 
  forests 
  of 
  Irkutsk 
  ; 
  young 
  plantations, 
  

   up 
  to 
  10 
  years 
  are 
  seldom 
  attacked, 
  unless 
  they 
  are 
  situated 
  in 
  the 
  

   neighbourhood 
  of 
  an 
  infected 
  area 
  ; 
  otherwise 
  they 
  are 
  only 
  attacked 
  

   after 
  the 
  older 
  trees 
  are 
  laid 
  bare. 
  While 
  it 
  is 
  admitted 
  that 
  the 
  yomig 
  

   larvae 
  of 
  D. 
  segregatus 
  may 
  possibly 
  be 
  distributed 
  by 
  the 
  wind, 
  the 
  

   older 
  caterpillars 
  are 
  able 
  to 
  migrate 
  only 
  for 
  short 
  distances. 
  The 
  

   geographical 
  distribution 
  of 
  D. 
  segregatus 
  includes 
  the 
  whole 
  of 
  North 
  

   Asia, 
  from 
  the 
  Ural 
  Mountains 
  to 
  Japan, 
  the 
  north-western 
  hmit 
  of 
  

   its 
  distribution 
  being 
  Syrostan, 
  in 
  the 
  Southern 
  Ural. 
  The 
  author 
  

   gives 
  a 
  short 
  history 
  of 
  the 
  devastation 
  caused 
  by 
  this 
  pest 
  since 
  1892, 
  

   when 
  attention 
  was 
  first 
  drawn 
  to 
  the 
  enormous 
  damage 
  caused 
  by 
  it 
  

   in 
  the 
  " 
  taiga 
  " 
  of 
  Eastern 
  Siberia 
  ; 
  the 
  local 
  population 
  had 
  known 
  

   the 
  larvae 
  for 
  15-20 
  years 
  previously. 
  Most 
  of 
  the 
  attack 
  was 
  con- 
  

   centrated 
  in 
  two 
  districts 
  of 
  the 
  government 
  of 
  Irkutsk 
  and 
  it 
  is 
  cal- 
  

   culated 
  that 
  the 
  damage 
  there 
  amounted 
  to 
  more 
  than 
  £55,000, 
  several 
  

   hundred 
  thousand 
  dessiatines 
  (2*7 
  acres) 
  of 
  forests 
  being 
  destroyed 
  or 
  

   injured. 
  In 
  these 
  districts 
  may 
  be 
  seen 
  enormous 
  areas 
  of 
  dead 
  

   and 
  dying 
  forests 
  of 
  cedars, 
  firs 
  and 
  larches. 
  Young 
  trees, 
  of 
  up 
  to 
  

   20-30 
  years, 
  die 
  in 
  the 
  same 
  year 
  ; 
  the 
  older 
  cedars 
  and 
  firs, 
  w^hen 
  

   damaged 
  by 
  B. 
  segregatus, 
  are 
  usually 
  subjected 
  afterwards 
  to 
  attacks 
  

  

  