﻿36 
  

  

  CIRCULAR 
  2 
  7 
  0, 
  U. 
  S. 
  DEPARTMEXT 
  OF 
  AGRICULTURE 
  

  

  prune, 
  apricot, 
  and 
  peach 
  trees, 
  

   and 
  also 
  on 
  other 
  fruit 
  and 
  shade 
  

   trees. 
  It 
  winters 
  as 
  a 
  nearly 
  ma- 
  

   ture 
  insect. 
  laTing- 
  eggs 
  beneath 
  the 
  

   shell 
  in 
  the 
  spring. 
  The 
  eggs 
  

   hatch 
  from 
  May 
  to 
  July, 
  and 
  the 
  

   young 
  settle 
  on 
  the 
  twigs 
  and 
  

   leaves. 
  There 
  is 
  only 
  one 
  genera- 
  

   tion 
  a 
  year. 
  This 
  scale 
  may 
  be 
  

   controlled 
  with 
  the 
  usual 
  dormant 
  - 
  

   season 
  applications 
  of 
  lime-sulfur 
  

   (table 
  1, 
  p. 
  60) 
  or 
  oil 
  emulsions, 
  

   the 
  oil 
  being 
  more 
  effective. 
  

  

  Aphids 
  

  

  Foiu* 
  or 
  five 
  species 
  of 
  aphids 
  

   occur 
  on 
  primes 
  and 
  plmns 
  in 
  the 
  

   Pacific 
  Xorthwest. 
  All 
  have 
  sim- 
  

   ilar 
  habits 
  and 
  may 
  be 
  controlled 
  

   in 
  the 
  same 
  manner. 
  One 
  of 
  the 
  

   commonest 
  species 
  is 
  the 
  hop 
  

   aphid, 
  which 
  is 
  a 
  serious 
  pest 
  of 
  

   hops 
  but 
  spends 
  a 
  part 
  of 
  the 
  year 
  

  

  /. 
  

  

  ..^^•^ 
  

  

  Figure 
  43.- 
  

  

  -Mealy 
  plum 
  aphids 
  on 
  plum 
  

   foliage. 
  

  

  on 
  

  

  prime 
  trees. 
  Planting 
  hops 
  

   near 
  prune 
  orchards 
  should 
  there- 
  

   fore 
  be 
  avoided, 
  if 
  possible. 
  This 
  

   green 
  aphid 
  often 
  covers 
  the 
  under 
  

   surface 
  of 
  the 
  leaves 
  of 
  prune 
  trees 
  

   early 
  in 
  the 
  season. 
  The 
  mealy 
  

   plum 
  aphid 
  is 
  bluish-green 
  with 
  

   a 
  whitish, 
  powdery 
  covering 
  

   (fig. 
  ttS). 
  It 
  frequently 
  becomes 
  

  

  exceedingly 
  abundant 
  on 
  the 
  under 
  

   surface 
  of 
  the 
  leaves. 
  The 
  thistle 
  

   aphid, 
  a 
  leaf 
  -curling 
  plum 
  aphid, 
  

   and 
  the 
  green 
  peach 
  aphid 
  also 
  

   occur 
  on 
  prune 
  and 
  plum 
  trees, 
  

   and 
  occasionally 
  become 
  abundant. 
  

   These 
  aphids 
  are 
  green 
  or 
  reddish 
  

   and 
  they 
  curl 
  the 
  leaves 
  consider- 
  

   ably. 
  All 
  these 
  species 
  are 
  of 
  

   European 
  origin. 
  

  

  LIFE 
  HISTORY 
  

  

  The 
  life 
  histories 
  of 
  these 
  aphids 
  

   are 
  similar. 
  Wintering 
  eggs 
  are 
  

   laid 
  on 
  the 
  trees 
  and 
  hatch 
  early 
  in 
  

   the 
  spring 
  before 
  the 
  buds 
  have 
  

   swelled 
  appreciably. 
  The 
  young 
  

   feed 
  within 
  the 
  opening 
  buds 
  and 
  

   on 
  the 
  leaves. 
  After 
  several 
  gen- 
  

   erations 
  have 
  developed 
  on 
  the 
  

   prune 
  trees, 
  winged 
  forms 
  develop 
  

   and 
  fly 
  to 
  the 
  summer 
  host 
  plants, 
  

   and 
  later 
  generations 
  return 
  to 
  the 
  

   trees 
  in 
  the 
  fall. 
  During 
  the 
  sum- 
  

   mer 
  the 
  hop 
  aphid 
  is 
  found 
  on 
  the 
  

   hops, 
  the 
  mealy 
  plum 
  aphid 
  on 
  

   reed 
  grasses 
  and 
  cattails, 
  the 
  this- 
  

   tle 
  aphid 
  on 
  thistles, 
  chrysanthe- 
  

   mums, 
  and 
  other 
  plants, 
  and 
  the 
  

   other 
  two 
  species 
  on 
  many 
  kinds 
  of 
  

   wild 
  and 
  cultivated 
  plants. 
  

  

  CONTROL 
  

  

  Ordinarily 
  a 
  dormant-season 
  ap- 
  

   plication 
  of 
  oil 
  emulsion 
  contain- 
  

   ing 
  4 
  percent 
  of 
  oil 
  is 
  fairly 
  effec- 
  

   tive 
  in 
  controlling 
  aphids 
  on 
  

   prune 
  and 
  plum 
  trees. 
  If 
  lime- 
  

   sulfur 
  is 
  used, 
  nicotine 
  sulfate 
  

   should 
  be 
  added 
  to 
  it 
  at 
  three- 
  

   fourths 
  pint 
  to 
  100 
  gallons 
  of 
  

   water. 
  If 
  the 
  dormant 
  spray 
  has 
  

   not 
  been 
  applied, 
  and 
  the 
  infesta- 
  

   tion 
  becomes 
  serious, 
  one 
  of 
  the 
  

   contact 
  materials, 
  such 
  as 
  nicotine 
  

   or 
  parathion, 
  may 
  be 
  used 
  effec- 
  

   tively 
  as 
  a 
  spray 
  or 
  dust. 
  (See 
  

   Cautions, 
  p. 
  59.) 
  

  

  Orchard 
  Mites 
  

  

  Prune 
  and 
  plum 
  trees 
  are 
  often 
  

   seriously 
  affected 
  by 
  orchard 
  mites. 
  

   The 
  foliao-e 
  is 
  bronzed, 
  and 
  de- 
  

  

  