﻿CIHCULAR 
  2 
  70, 
  U. 
  S. 
  DEPARTMENT 
  OF 
  AGRICULTURE 
  

  

  their 
  long, 
  threadlike 
  beaks 
  into 
  

   the 
  plant 
  tissue, 
  and 
  begin 
  feeding. 
  

   Almost 
  at 
  once 
  they 
  begin 
  to 
  

   secrete 
  a 
  waxy 
  material, 
  which 
  

   soon 
  forms 
  a 
  circular, 
  scalelike 
  

   covering. 
  The 
  covering 
  of 
  the 
  

   full-grown 
  female 
  is 
  about 
  the 
  

   size 
  of 
  a 
  pinhead 
  and 
  grayish, 
  with 
  

   a 
  dark, 
  central 
  nipple-like 
  projec- 
  

   tion, 
  whereas 
  that 
  of 
  the 
  male 
  is 
  

   elongated 
  (fig. 
  4, 
  6^). 
  Underneath 
  

   these 
  coverings 
  the 
  delicate, 
  

   bright-yellow, 
  saclike 
  bodies 
  of 
  the 
  

   insects 
  may 
  be 
  seen. 
  . 
  Growth 
  is 
  

   completed 
  in 
  about 
  6 
  weeks, 
  and 
  

   there 
  are 
  two 
  or 
  more 
  generations 
  

   in 
  a 
  season. 
  

  

  CONTROL 
  

  

  Ordinary 
  infestations 
  may 
  be 
  

   controlled 
  with 
  a 
  single 
  thorough 
  

   application 
  of 
  lubricating 
  - 
  oil 
  

   emulsion 
  or 
  liquid 
  lime-sulfur 
  

   during 
  the 
  dormant 
  season. 
  More 
  

   than 
  1 
  year 
  may 
  be 
  required 
  to 
  

   bring 
  very 
  heavy 
  infestations 
  

   under 
  control. 
  

  

  The 
  material 
  to 
  use 
  depends 
  on 
  

   what 
  other 
  insects 
  are 
  on 
  the 
  trees 
  

   at 
  the 
  same 
  time. 
  Oil 
  sprays 
  are 
  

   effective 
  against 
  the 
  eggs 
  of 
  red 
  

   spiders, 
  treehoppers, 
  and 
  the 
  fruit 
  

   tree 
  leaf 
  roller, 
  and 
  against 
  newly 
  

   hatched 
  aphids, 
  and 
  should 
  be 
  

   used 
  if 
  these 
  eggs 
  or 
  insects 
  are 
  

   numerous; 
  otherwise 
  the 
  lime- 
  

   sulfur 
  is 
  just 
  as 
  satisfactory. 
  It 
  is 
  

   often 
  desired 
  to 
  control 
  the 
  pear 
  

   leaf 
  blister 
  mite 
  on 
  pear 
  trees, 
  and 
  

   for 
  this 
  purpose 
  lime-sulfur 
  is 
  

   preferable. 
  This 
  material 
  is 
  safer 
  

   than 
  oil 
  emulsion 
  for 
  use 
  during 
  

   the 
  delayed 
  dormant 
  period, 
  al- 
  

   though 
  a 
  sudden 
  onset 
  of 
  warm 
  

   weather 
  after 
  its 
  application 
  may 
  

   cause 
  the 
  fruit 
  buds 
  to 
  drop. 
  

   These 
  materials 
  should 
  be 
  applied 
  

   only 
  while 
  the 
  trees 
  are 
  dormant 
  

   (fig. 
  5). 
  If 
  the 
  spray 
  is 
  applied 
  

   after 
  the 
  trees 
  have 
  been 
  pruned, 
  

   less 
  material 
  is 
  required. 
  The 
  

   most 
  heavily 
  infested 
  limbs 
  may 
  

   often 
  be 
  removed 
  before 
  spraying. 
  

  

  On 
  medium 
  or 
  heavy 
  infesta- 
  

   tions 
  of 
  the 
  San 
  Jose 
  scale, 
  an 
  

   emulsion 
  containing 
  about 
  4 
  per- 
  

   cent 
  of 
  lubricating 
  oil 
  must 
  be 
  

   used. 
  For 
  very 
  light 
  infestations 
  

   a 
  3-percent 
  emulsion 
  may 
  be 
  suf- 
  

   ficient. 
  The 
  diluted 
  liquid 
  lime- 
  

   sulfur 
  must 
  test 
  at 
  least 
  4^/2° 
  

   Baume 
  for 
  most 
  infestations 
  (see 
  

   table 
  1, 
  p. 
  60) 
  . 
  Very 
  light 
  infesta- 
  

   tions 
  may 
  be 
  held 
  in 
  check 
  with 
  a 
  

   solution 
  testing 
  at 
  least 
  3i/2° 
  

   Baume. 
  

  

  Figure 
  5.- 
  — 
  Apple 
  buds 
  in 
  stage 
  of 
  

   development 
  for 
  dormant 
  spray. 
  

  

  A 
  mixture 
  of 
  oil 
  emulsion 
  and 
  

   liquid 
  lime-sulfur 
  is 
  often 
  useful 
  

   for 
  controlling 
  the 
  San 
  Jose 
  scale 
  ; 
  

  

  1 
  percent 
  of 
  actual 
  oil 
  and 
  3 
  per- 
  

   cent 
  of 
  lime-sulfur 
  is 
  effective. 
  If 
  

   it 
  is 
  desired 
  also 
  to 
  control 
  the 
  

   apple 
  aphids 
  (see 
  p. 
  15) 
  or 
  to 
  de- 
  

   stroy 
  orchard 
  mite 
  eggs 
  (see 
  p. 
  12) 
  

  

  2 
  percent 
  of 
  oil 
  should 
  be 
  used. 
  

   Only 
  the 
  paste 
  or 
  flowable 
  types 
  

   of 
  oil 
  emulsion 
  should 
  be 
  em- 
  

   ployed, 
  and 
  the 
  mixture 
  should 
  be 
  

   applied 
  when 
  the 
  trees 
  are 
  dor- 
  

   mant. 
  

  

  Oystershell 
  Scale 
  

  

  The 
  oystershell 
  scale 
  is 
  found 
  

   throughout 
  the 
  Northwest, 
  but 
  it 
  

   is 
  most 
  common 
  west 
  of 
  the 
  Cas- 
  

  

  