﻿SCALE 
  INSECTS 
  OF 
  IMPORTANCE 
  297 
  

  

  Appletree 
  bark 
  louse 
  

  

  Mytilaspis 
  poviorum 
  Bouche 
  

  

  PLATE 
  I 
  

  

  This 
  is 
  the 
  most 
  common 
  scale 
  insect 
  found 
  on 
  fruit 
  trees 
  in 
  New 
  York, 
  

   and 
  in 
  some 
  localities 
  it 
  is 
  very 
  abundant 
  and 
  destructive, 
  particularly 
  to 
  

   poplars 
  and 
  ash 
  in 
  the 
  vicinity 
  of 
  Albany. 
  This 
  pest 
  has 
  been 
  repeatedly 
  

   noticed 
  in 
  agricultural 
  and 
  entomologic 
  journals, 
  and 
  it 
  is 
  a 
  frequent 
  

   source 
  of 
  complaint 
  at 
  the 
  present 
  time. 
  A 
  few 
  of 
  the 
  more 
  important 
  

   articles 
  treating 
  of 
  this 
  insect 
  are 
  given 
  in 
  the 
  brief 
  bibhography 
  below. 
  

   This 
  European 
  species 
  was 
  probably 
  brought 
  to 
  America 
  on 
  early 
  impor- 
  

   tations 
  of 
  fruit 
  trees, 
  and 
  now 
  it 
  is 
  known 
  to 
  occur 
  all 
  over 
  the 
  world, 
  as 
  

   stated 
  by 
  Dr 
  L. 
  O. 
  Howard. 
  It 
  has 
  been 
  described 
  scientifically 
  several 
  

   times, 
  on 
  each 
  occasion 
  receiving 
  a 
  different 
  name, 
  and 
  it 
  also 
  passes 
  

   under 
  the 
  common 
  name 
  of 
  oyster 
  shell 
  bark 
  louse. 
  The 
  popular 
  desig- 
  

   nation 
  given 
  above 
  is 
  extensively 
  used, 
  and 
  it 
  is 
  preferable 
  on 
  account 
  of 
  

   its 
  being 
  more 
  characteristic 
  of 
  the 
  species. 
  

  

  Description. 
  The 
  adult 
  female 
  scales 
  can 
  easily 
  be 
  recognized 
  by 
  a 
  

   comparison 
  with 
  the 
  greatly 
  enlarged 
  figure 
  7 
  or 
  with 
  figure 
  9, 
  which 
  lat- 
  

   ter 
  represents 
  a 
  number 
  in 
  natural 
  size 
  on 
  poplar 
  bark. 
  The 
  adult 
  scale 
  is 
  

   about 
  3 
  mm, 
  or 
  |- 
  inch 
  long, 
  usually 
  slightly 
  curved 
  and 
  widening 
  from 
  

   a 
  slender 
  lip 
  to 
  a 
  broad, 
  rounded 
  posterior 
  end. 
  The 
  scale 
  has 
  at 
  its 
  

   pointed 
  or 
  anterior 
  end 
  a 
  usually 
  yellowish, 
  very 
  small 
  pellicle, 
  the 
  first 
  

   cast 
  skin 
  of 
  the 
  young, 
  and 
  a 
  small 
  scale 
  three 
  times 
  its 
  size 
  attached 
  to 
  

   it. 
  There 
  is 
  also 
  a 
  larger 
  or 
  second 
  cast 
  skin, 
  and 
  to 
  it 
  is 
  attached 
  the 
  

   -larger 
  or 
  chief 
  part 
  of 
  the 
  scale, 
  which 
  is 
  a 
  variable 
  brown 
  and 
  marked 
  

   with 
  curved 
  transverse 
  lines 
  or 
  wrinkles. 
  The 
  first 
  cast 
  skin 
  can 
  be 
  

   -detected 
  only 
  on 
  microscopic 
  examination. 
  The 
  female 
  insect 
  found 
  

   midemeath 
  the 
  covering 
  scale 
  is 
  represented 
  in 
  figure 
  10. 
  The 
  male 
  

   scale 
  is 
  smaller, 
  and 
  is 
  shown 
  in 
  figure 
  6. 
  A 
  female 
  scale 
  turned 
  over 
  in 
  

   winter 
  presents 
  the 
  appearance 
  represented 
  in 
  figure 
  8. 
  The 
  shriveled, 
  

   yellowish' 
  or 
  brown 
  body 
  of 
  the 
  female 
  occupies 
  the 
  anterior 
  portion 
  of 
  

   the 
  scale 
  cavity, 
  while 
  in 
  the 
  posterior 
  part 
  are 
  numerous 
  oval, 
  white 
  

   eggs, 
  shown 
  greatly 
  enlarged 
  in 
  figure 
  i. 
  The 
  minute, 
  yellow, 
  recently 
  

   hatched 
  scale 
  insect 
  is 
  represented 
  in 
  figure 
  2, 
  and 
  the 
  condition 
  of 
  a 
  

   -number 
  shortly 
  after 
  estabhshing 
  themselves 
  on 
  a 
  twig, 
  in 
  figure 
  3. 
  The 
  

   appearance 
  of 
  the 
  young 
  after 
  it 
  has 
  secreted 
  a 
  protecting 
  scale 
  is 
  repre- 
  

   ■sented 
  in 
  figure 
  4, 
  a 
  few 
  being 
  shown 
  much 
  enlarged 
  in 
  figure 
  5. 
  

  

  Lite 
  history. 
  This 
  insect 
  completes 
  the 
  round 
  of 
  life 
  once 
  a 
  year 
  in 
  

   this 
  latitude, 
  though 
  in 
  the 
  southern 
  states 
  two 
  generations 
  may 
  be 
  pro- 
  

  

  