﻿Eepoet 
  of 
  the 
  Botanist. 
  35 
  

  

  from 
  one-half 
  to 
  two 
  -thirds 
  of 
  the 
  spruces 
  with 
  a 
  basal 
  diam- 
  

   eter 
  ranging 
  from 
  one 
  to 
  two 
  feet 
  were 
  either 
  dead 
  or 
  dying. 
  

   Trees 
  of 
  this 
  size 
  are 
  the 
  most 
  suitable 
  for 
  lumber 
  and 
  conse- 
  

   quently 
  the 
  most 
  valuable. 
  The 
  smallest 
  affected 
  tree 
  noticed, 
  

   had 
  an 
  estimated 
  basal 
  diameter 
  of 
  about 
  ten 
  inches. 
  In 
  this 
  

   case 
  the 
  attack 
  appeared 
  to 
  be 
  a 
  failure, 
  for 
  so 
  much 
  resin 
  had 
  

   oozed 
  from 
  the 
  wounds 
  that 
  the 
  work 
  was 
  obstructed. 
  The 
  

   galleries 
  were 
  scattered 
  and 
  single 
  and 
  their 
  authors 
  were 
  

   found 
  dead, 
  each 
  in 
  its 
  furrow. 
  No 
  larvse 
  were 
  present, 
  and 
  

   the 
  apparent 
  attempt 
  to 
  establish 
  a 
  colony 
  in 
  this 
  tree 
  had 
  

   thus 
  far 
  failed. 
  But 
  it 
  may 
  be 
  that 
  this 
  tree 
  had 
  only 
  been 
  

   attacked 
  for 
  the 
  purpose 
  of 
  obtaining 
  food, 
  and 
  had 
  not 
  yet 
  

   been 
  brought 
  into 
  that 
  sickly, 
  languishing 
  condition 
  thought 
  by 
  

   some 
  entomologists 
  to 
  be 
  necessary 
  to 
  induce 
  the 
  establish- 
  

   ment 
  of 
  a 
  colony, 
  the 
  deposition 
  of 
  eggs 
  and 
  the 
  develop- 
  

   ment 
  of 
  larvae. 
  For 
  it 
  is 
  said 
  of 
  Scolytus 
  destructor, 
  a, 
  bark- 
  

   mining 
  beetle 
  that 
  sometimes 
  proves 
  very 
  destructive 
  to 
  elm 
  

   trees 
  in 
  Europe, 
  that 
  the 
  adult 
  insects 
  first 
  attack 
  healthy 
  

   trees 
  for 
  the 
  purpose 
  of 
  obtaining 
  food, 
  and 
  when, 
  by 
  this 
  

   means 
  the 
  vigor 
  of 
  the 
  tree 
  has 
  become 
  somewhat 
  impaired, 
  

   the 
  female 
  deposits 
  her 
  eggs 
  in 
  her 
  galleries. 
  Then 
  the 
  rapidly 
  

   increasing 
  numbers 
  soon 
  destroy 
  the 
  life 
  of 
  the 
  tree. 
  

  

  When 
  two 
  trees 
  of 
  unequal 
  size 
  stand 
  in 
  close 
  proximity 
  

   the 
  larger 
  one 
  seems 
  to 
  be 
  most 
  liable 
  to 
  be 
  attacked. 
  In 
  

   one 
  instance 
  two 
  trees 
  stood 
  scarcely 
  more 
  than 
  three 
  feet 
  

   apart. 
  The 
  larger 
  one 
  had 
  been 
  attacked 
  ; 
  the 
  smaller 
  

   remained 
  unharmed. 
  In 
  another 
  similar 
  instance 
  the 
  larger 
  

   of 
  the 
  two 
  trees 
  was 
  dead, 
  having 
  been 
  attacked 
  first 
  ; 
  the 
  other 
  

   was 
  dying. 
  Why 
  this 
  preference 
  on 
  the 
  part 
  of 
  these 
  insects 
  

   for 
  the 
  largest 
  trees 
  ? 
  It 
  may 
  be 
  that 
  young 
  trees 
  are 
  apt 
  to 
  be 
  

   too 
  resinous 
  to 
  be 
  attacked 
  successfully. 
  In 
  the 
  case 
  of 
  the 
  

   small 
  tree 
  already 
  mentioned 
  the 
  gummy 
  exudations 
  from 
  the 
  

   perforations 
  in 
  the 
  bark 
  first 
  attracted 
  my 
  attention. 
  Or 
  the 
  

   insects 
  may 
  instinctively 
  know 
  that 
  a 
  tree 
  with 
  a 
  large 
  trunk 
  

   presents 
  a 
  broader 
  field 
  for 
  their 
  operations 
  than 
  one 
  with 
  a 
  

   small 
  trunk 
  ; 
  or 
  possibly 
  the 
  vigor 
  of 
  the 
  tree 
  may 
  be 
  so 
  im- 
  

   paired 
  by 
  age 
  that 
  it 
  is 
  more 
  readily 
  brought 
  into 
  suitable 
  

   condition 
  for 
  the 
  habitation 
  of 
  these 
  parasites. 
  Whatever 
  the 
  

   cause 
  of 
  this 
  selection, 
  no 
  diseased 
  condition 
  of 
  the 
  trees 
  was 
  

   detected 
  except 
  that 
  which 
  was 
  accompanied 
  by 
  and 
  to 
  all 
  

   appearance 
  was 
  directly 
  due 
  to 
  the 
  insects 
  themselves. 
  Cer- 
  

  

  