﻿ORCHARD 
  INSECTS 
  PACIFIC 
  NORTHWEST 
  

  

  29 
  

  

  LIFE 
  HISTORY 
  

  

  The 
  adult 
  insects 
  are 
  sawflies 
  

   similar 
  in 
  appearance 
  to 
  those 
  of 
  

   the 
  pear-slug, 
  but 
  more 
  slender 
  

   and 
  with 
  some 
  yellowish 
  mark- 
  

   ings. 
  They 
  emerge 
  from 
  the 
  

   ground 
  early 
  in 
  April 
  and 
  cut 
  slits 
  

   in 
  the 
  lower 
  surfaces 
  of 
  the 
  partly 
  

   unfolded 
  leaves, 
  in 
  which 
  the 
  eggs 
  

   are 
  laid. 
  The 
  wounds 
  often 
  cause 
  

   the 
  leaves 
  to 
  become 
  deformed. 
  

   The 
  small 
  green 
  worms 
  hatch 
  in 
  

   10 
  days 
  or 
  2 
  weeks 
  and 
  feed 
  as 
  de- 
  

   scribed 
  above. 
  

  

  Figure 
  35. 
  — 
  Pear 
  leaf 
  worm: 
  A, 
  Injury 
  to 
  

   leaf; 
  B, 
  egg 
  in 
  tissue 
  and 
  young 
  larva 
  

   feeding 
  (enlarged); 
  C, 
  full-grown 
  larva 
  

   (enlarged). 
  

  

  CONTROL 
  

  

  The 
  pear 
  leaf 
  worm 
  is 
  easily 
  

   controlled 
  with 
  lead 
  arsenate 
  at 
  2 
  

   pounds 
  to 
  100 
  gallons 
  of 
  water, 
  ap- 
  

   plied 
  just 
  after 
  the 
  petals 
  have 
  

   fallen. 
  

  

  Dock 
  Sawfly 
  

  

  Apples 
  are 
  occasionally 
  found 
  

   in 
  the 
  fall 
  with 
  round 
  holes 
  in 
  

   them 
  resembling 
  those 
  made 
  by 
  

   full-grown 
  codling 
  moth 
  larvae. 
  

   If 
  the 
  fruit 
  is 
  cut 
  open, 
  a 
  bright- 
  

   green 
  worm 
  may 
  be 
  found 
  inside 
  

   ( 
  fig. 
  36) 
  . 
  This 
  'is 
  the 
  larva 
  of 
  the 
  

   dock 
  sawfly, 
  an 
  insect 
  that 
  has 
  

   come 
  in 
  from 
  Europe. 
  The 
  adult 
  

  

  sawfly 
  lays 
  eggs 
  in 
  the 
  leaves 
  of 
  

   dock, 
  wild 
  buckwheat, 
  sheep 
  sorrel, 
  

   and 
  related 
  plants, 
  which 
  grow 
  

   along 
  ditch 
  banks 
  and 
  in 
  moist 
  

   places 
  in 
  orchards. 
  The 
  young 
  

   feed 
  on 
  these 
  same 
  plants, 
  and 
  

   when 
  full-grown 
  they 
  search 
  for 
  

   suitable 
  places 
  in 
  which 
  to 
  trans- 
  

   form 
  to 
  adults. 
  Usually 
  they 
  bur- 
  

   row 
  into 
  the 
  dry, 
  hollow 
  or 
  pithy, 
  

   stems 
  of 
  alfalfa 
  or 
  mustard, 
  or 
  

  

  k 
  

  

  Figure 
  36. 
  

  

  -Larva 
  of 
  the 
  dock 
  sawfly 
  in 
  

   an 
  apple. 
  

  

  into 
  the 
  stems 
  of 
  their 
  food 
  

   plants. 
  But 
  if 
  apples 
  are 
  near 
  by, 
  

   and 
  particularly 
  if 
  they 
  are 
  hang- 
  

   ing 
  low 
  in 
  the 
  cover 
  crop, 
  the 
  

   worms 
  may 
  construct 
  cells 
  in 
  the 
  

   apples 
  instead 
  of 
  in 
  the 
  plant 
  

   stems. 
  The 
  injury 
  caused 
  by 
  this 
  

   insect 
  is 
  ordinarily 
  negligible. 
  If 
  

   it 
  should 
  become 
  serious, 
  it 
  can 
  be 
  

   reduced 
  by 
  keeping 
  the 
  orchard 
  

   free 
  of 
  dock 
  and 
  related 
  plants 
  or 
  

   by 
  propping 
  up 
  low-hanging 
  

   branches, 
  and 
  by 
  banding 
  the 
  

  

  