﻿THE 
  SAN 
  JOSE 
  SCALE 
  IX 
  TLLIXOIS. 
  

  

  (Aspidiotus 
  peniiciosiis 
  Comstock.)* 
  

  

  The 
  San 
  Jose 
  scale 
  is 
  the 
  injurious 
  insect 
  of 
  the 
  hour 
  in 
  the 
  

   United 
  States. 
  Its 
  appearance 
  on 
  the 
  Pacific 
  Coast 
  about 
  1870 
  and 
  

   its 
  insidious 
  spread 
  throughout 
  the 
  country, 
  until 
  it 
  now 
  infests 
  at 
  

   least 
  twentj^-one 
  states, 
  have 
  caused 
  an 
  excitement 
  among 
  those 
  

   economically 
  concerned 
  which 
  recalls 
  that 
  attending 
  the 
  invasion 
  of 
  

   the 
  potato 
  fields 
  by 
  the 
  Colorado 
  potato 
  beetle 
  and 
  the 
  American 
  

   advent 
  and 
  rapid 
  distribution 
  of 
  the 
  European 
  cabbage 
  butterfly. 
  It 
  

   seems, 
  indeed, 
  to 
  be 
  in 
  many 
  respects 
  a 
  much 
  more 
  serious 
  pest 
  than 
  

   either 
  of 
  these, 
  infesting 
  a 
  greater 
  number 
  of 
  valuable 
  plants, 
  making 
  

   its 
  way 
  from 
  point 
  to 
  point 
  more 
  secretly, 
  although 
  more 
  slowly, 
  and 
  

   being 
  much 
  more 
  difficult 
  to 
  detect 
  in 
  its 
  first 
  appearances. 
  Its 
  

   recognition 
  and 
  arrest 
  are. 
  in 
  fact, 
  at 
  present 
  quite 
  beyond 
  the 
  knowl- 
  

   edge 
  and 
  powers 
  of 
  observation 
  of 
  the 
  ordinary 
  fruit 
  grower 
  or 
  com- 
  

   mercial 
  nurseryman, 
  and 
  it 
  is 
  not 
  surprising 
  that 
  the 
  alarmed 
  and 
  

   helpless 
  owners 
  of 
  property 
  liable 
  to 
  destruction 
  by 
  it 
  should 
  have 
  

   turned 
  very 
  generally 
  to 
  their 
  state 
  and 
  national 
  legislatures 
  for 
  pro- 
  

   tection 
  and 
  relief. 
  

  

  FOOD 
  PLANTS. 
  

  

  Unlike 
  the 
  other 
  leading 
  scale 
  insects 
  of 
  the 
  orchard, 
  this 
  scale 
  is 
  

   almost 
  equally 
  at 
  home 
  on 
  a 
  large 
  number 
  of 
  our 
  most 
  valuable 
  

   fruiting 
  trees 
  and 
  shrubs, 
  very 
  few 
  of 
  those 
  thriving 
  in 
  our 
  tem- 
  

   perate 
  climate 
  being 
  safe 
  from 
  its 
  attack. 
  No 
  experiments 
  have 
  

   been 
  made 
  to 
  determine 
  the 
  possible 
  variety 
  of 
  its 
  food 
  plants, 
  but 
  

   it 
  has 
  been 
  found 
  occurring 
  spontaneously 
  on 
  the 
  apple, 
  pear, 
  peach, 
  

   apricot, 
  plum, 
  cherry, 
  quince, 
  grape, 
  raspberry, 
  l)lackberry. 
  goose- 
  

   berry, 
  currant, 
  and 
  persimmon 
  among 
  our 
  fruits: 
  on 
  the 
  hickory, 
  

   pecan, 
  the 
  English 
  walnut, 
  and 
  the 
  almond 
  among 
  the 
  nut-bearing 
  

   trees; 
  on 
  the 
  oak, 
  basswood, 
  elm, 
  chestnut, 
  birch, 
  and 
  willow 
  among 
  

   our 
  shade 
  and 
  forest 
  trees: 
  and 
  on 
  a 
  large 
  miscellaneous 
  list 
  of 
  trees 
  

   and 
  shrubs, 
  including 
  the 
  rose, 
  thorn-apple 
  (CratfBgus), 
  crab-apple, 
  

   wahoo, 
  spirea, 
  loquat, 
  cotoneaster, 
  flowering 
  quince, 
  flowering 
  cur- 
  

   rant, 
  acacia, 
  alder, 
  and 
  sumach. 
  It 
  also 
  seriously 
  infests 
  the 
  osage 
  

   orange, 
  spreading 
  with 
  the 
  greatest 
  facility 
  through 
  the 
  thick 
  growth 
  

   of 
  the 
  wayside 
  hedge. 
  

  

  *The 
  San 
  Jose 
  scale 
  \s'as 
  first 
  discovered 
  in 
  Illinois 
  in 
  September, 
  18%, 
  and 
  little 
  oppor- 
  

   tunity 
  has 
  since 
  been 
  aiforded 
  for 
  independent 
  investigation 
  of 
  it. 
  The 
  main 
  dependence 
  

   in 
  the 
  preparation 
  of 
  this 
  paper 
  has 
  consetdiently 
  been 
  a 
  special 
  Bulletin 
  on 
  that 
  insect 
  

   prepared 
  by 
  Messrs, 
  Howard 
  and 
  JIarlatt 
  in 
  1896. 
  and 
  Professor 
  John 
  B. 
  Smith's 
  description 
  

   of 
  his 
  observations 
  in 
  California 
  and 
  New 
  Jersey, 
  printed 
  in 
  his 
  Report 
  for 
  1896 
  as 
  Entomologist 
  

   of 
  the 
  New 
  Jersey 
  Agricultural 
  College 
  Experiment 
  Station. 
  Although 
  written 
  origi- 
  

   nally 
  to 
  cover 
  only 
  the 
  work 
  of 
  1896. 
  this 
  article 
  has 
  since 
  been 
  revised 
  to 
  include 
  field 
  obser- 
  

   ■ 
  vations 
  made 
  up 
  to 
  October 
  15, 
  1897. 
  

  

  