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  themselves 
  but 
  imperfectly 
  ascertained, 
  and 
  Professor 
  Smith's 
  own 
  

   observations 
  extended 
  over 
  too 
  brief 
  a 
  time 
  to 
  serve 
  as 
  satisfactory 
  

   clues 
  to 
  the 
  labyrinth. 
  

  

  It 
  is 
  safe 
  to 
  conclude, 
  however, 
  that 
  the 
  San 
  Jose 
  scale 
  has 
  largely 
  

   diminished 
  in 
  numbers, 
  or 
  even 
  almost 
  wholly 
  disappeared, 
  in 
  some 
  

   parts 
  of 
  California 
  where 
  it 
  was 
  formerly 
  widespread, 
  excessively 
  

   numerous, 
  and 
  exceedingly 
  destructive. 
  Even 
  at 
  San 
  Jose 
  Profes- 
  

   sor 
  Smith 
  says 
  that 
  it 
  is 
  not 
  now 
  injurious, 
  although 
  it 
  was 
  plenti- 
  

   fulh^ 
  scattered 
  on 
  abandoned 
  trees 
  and 
  occurred 
  in 
  moderate 
  num- 
  

   bers 
  in 
  several 
  cultivated 
  orchards. 
  It 
  also 
  seems 
  clear 
  that 
  this 
  a^j- 
  

   parently 
  spontaneous 
  disappearance 
  has 
  been 
  most 
  general 
  and 
  com- 
  

   plete 
  in 
  southern 
  California; 
  that 
  it 
  is 
  confined, 
  in 
  fact, 
  to 
  points 
  

   from 
  San 
  Jose 
  southward. 
  Some 
  of 
  its 
  causes 
  are 
  manifest, 
  but 
  

   some 
  assumed 
  causes 
  are 
  doul)tful 
  or 
  obscure, 
  and 
  the 
  share 
  of 
  each 
  

   in 
  the 
  effect 
  produced 
  it 
  is 
  impossible 
  to 
  estimate 
  definitely. 
  Un- 
  

   favorable 
  climatic 
  conditions, 
  insect 
  enemies, 
  either 
  predaceous 
  or 
  

   parasitic, 
  and 
  fungus 
  diseases 
  are 
  the 
  agencies 
  known 
  or 
  suspected. 
  

  

  Climatic 
  Checks. 
  — 
  It 
  is 
  a 
  fair 
  inference 
  from 
  reported 
  observations 
  

   that 
  the 
  scale 
  does 
  not 
  thrive 
  permanently 
  in 
  a 
  very 
  hot 
  and 
  dry 
  

   climate, 
  or 
  even 
  in 
  one 
  subject 
  to 
  a 
  long 
  period 
  of 
  midsummer 
  heat 
  

   and 
  drouth. 
  It 
  has 
  been 
  sometimes 
  surmised 
  that 
  very 
  cold 
  weather 
  

   is 
  unfavorable 
  to 
  its 
  continuance. 
  It 
  is 
  reported 
  by 
  Professor 
  Smith 
  

   to 
  have 
  survived 
  in 
  New 
  Jersey 
  a 
  zero 
  temperature 
  and 
  its 
  con- 
  

   tinuance 
  for 
  four 
  years 
  on 
  a 
  single 
  tree 
  in 
  Ogle 
  county, 
  near 
  the 
  

   northern 
  line 
  of 
  the 
  State 
  of 
  Illinois, 
  is 
  still 
  more 
  convincing 
  evi- 
  

   dence 
  of 
  its 
  capacity 
  to 
  withstand 
  low 
  temperatures. 
  From 
  reports 
  

   of 
  the 
  U. 
  S. 
  Weather 
  Bureau, 
  kindly 
  sent 
  me 
  by 
  Mr. 
  Charles 
  E. 
  Lin- 
  

   ney. 
  Observer 
  in 
  Chicago, 
  it 
  appears 
  that 
  the 
  temperature 
  record 
  in 
  

   Oregon, 
  Ogle 
  county, 
  reached 
  20" 
  below 
  zero 
  (Fahrenheit) 
  in 
  1894, 
  

   26'^ 
  below 
  zero 
  in 
  1895, 
  and 
  15" 
  below 
  zero 
  in 
  1896. 
  Indeed, 
  the 
  en- 
  

   tire 
  "month 
  from 
  the 
  20th 
  of 
  January, 
  1895, 
  to 
  the 
  20th 
  of 
  February 
  

   following 
  was 
  a 
  period 
  of 
  extreme 
  cold, 
  probably 
  lower 
  than 
  any 
  like 
  

   period 
  since 
  systematic 
  records 
  have 
  been 
  kept 
  within 
  the 
  State." 
  

   This 
  fact 
  further 
  goes 
  to 
  show 
  that 
  the 
  supposed 
  limitation 
  of 
  the 
  

   distribution 
  of 
  this 
  scale 
  to 
  the 
  austral 
  zone 
  cannot 
  be 
  depended 
  upon, 
  

   since 
  a 
  climate 
  such 
  as 
  that 
  indicated 
  by 
  the 
  above 
  temperature 
  rec- 
  

   ords 
  would 
  exclude 
  the 
  Ogle 
  county 
  situation 
  from 
  this 
  zone. 
  

  

  Entomological 
  Enetiiies. 
  — 
  The 
  recognized 
  species 
  of 
  predaceous 
  

   insect 
  enemies 
  of 
  this 
  scale 
  are 
  six 
  in 
  number, 
  and 
  the 
  recorded 
  para- 
  

   sitic 
  insect 
  species 
  are 
  five. 
  Only 
  three 
  of 
  these 
  are 
  worthy 
  of 
  

   present 
  attention 
  as 
  highly 
  destructive 
  enemies 
  of 
  the 
  scale, 
  one 
  a 
  

   parasite 
  {ApJielinusfuscipemiis) 
  and 
  two 
  predaceous 
  enemies 
  (C/r?7o- 
  

   corus 
  hivnlnerns 
  and 
  Smilia, 
  misella) 
  . 
  These 
  three 
  are 
  native 
  

   American 
  species, 
  occur 
  throughout 
  the 
  United 
  States 
  from 
  the 
  

   Atlantic 
  Ocean 
  to 
  the 
  Pacific, 
  and 
  live 
  on 
  scale 
  insects 
  generally. 
  

   It 
  seems 
  quite 
  likely, 
  as 
  suggested 
  by 
  Professor 
  Smith, 
  that 
  other 
  

   insect 
  enemies 
  of 
  our 
  coccids 
  may 
  attack 
  the 
  San 
  Jose 
  species, 
  if 
  

   they 
  have 
  opportunity, 
  as 
  freely 
  as 
  they 
  do 
  our 
  native 
  orchard 
  scales. 
  

   There 
  is 
  evidently 
  a 
  wide 
  and 
  promising 
  field 
  for 
  experiment 
  here, 
  

   one 
  in 
  which 
  work 
  can 
  be 
  carried 
  on 
  readily 
  and 
  at 
  small 
  expense. 
  

  

  