﻿EFFECT 
  OF 
  THE 
  LARVA 
  ON 
  WHEAT. 
  213 
  

  

  to 
  mature 
  so 
  as 
  to 
  fly 
  again, 
  thougli 
  they 
  might 
  hatch 
  a 
  little 
  sooner 
  or 
  later 
  in 
  the 
  

   open 
  field. 
  I 
  cannot 
  say 
  as 
  to 
  that; 
  have 
  no 
  certain 
  means 
  of 
  knowing. 
  

  

  The 
  flies 
  of 
  the 
  second 
  brood 
  are, 
  in 
  southern 
  Michigan, 
  read}^ 
  to 
  de- 
  

   posit 
  their 
  eggs 
  late 
  in 
  April 
  or 
  earlj^ 
  in 
  May 
  ^'on 
  spring 
  wheat 
  or 
  barley 
  

   which 
  is 
  sufficiently 
  advanced, 
  in 
  lieu 
  of 
  which 
  they 
  deposit 
  on 
  the 
  wheat 
  

   again, 
  not 
  on 
  the 
  basal 
  or 
  radical 
  leaves, 
  but 
  on 
  the 
  leaves 
  which 
  will 
  

   be 
  above 
  the 
  first 
  or 
  second, 
  rarely 
  the 
  third, 
  joints." 
  (Cook.) 
  

  

  Habits 
  of 
  the 
  larva, 
  — 
  As 
  soon 
  as 
  the 
  footless 
  larva 
  or 
  maggot 
  hatches, 
  

   it 
  makes 
  its 
  way 
  down 
  the 
  leaf 
  to 
  the 
  base 
  of 
  the 
  sheath, 
  which, 
  in 
  the 
  

   young 
  winter 
  wheat, 
  is 
  at 
  the 
  crown 
  of 
  the 
  root. 
  

  

  Here 
  [says 
  Herrick] 
  it 
  fastens, 
  lengthwise, 
  and 
  head 
  downwards, 
  to 
  the 
  tender 
  stalk, 
  

   and 
  lives 
  upon 
  the 
  sap. 
  It 
  does 
  not 
  gnaw 
  the 
  stalk, 
  nor 
  does 
  it 
  enter 
  the 
  central 
  cav- 
  

   ity 
  thereof; 
  but, 
  as 
  the 
  larva 
  increases 
  in 
  size, 
  it 
  gradually 
  becomes 
  imbedded 
  in 
  the 
  

   substance 
  of 
  the 
  stalk. 
  After 
  taking 
  its 
  station, 
  thQ 
  larva 
  moves 
  no 
  more, 
  gradually 
  

   loses 
  its 
  reddish 
  color 
  and 
  wrinkled 
  appearance, 
  becomes 
  plump 
  and 
  torpid, 
  is 
  at 
  first 
  

   semi-translucent, 
  and 
  then 
  more 
  and 
  more 
  clouded 
  with 
  intestinal 
  w^hite 
  spots; 
  and 
  

   w^hen 
  near 
  maturity, 
  the 
  middle 
  of 
  the 
  intestinal 
  parts 
  is 
  of 
  a 
  greenish 
  color. 
  In 
  five 
  

   or 
  six 
  weeks 
  (varying 
  with 
  the 
  season) 
  the 
  larva 
  begins 
  to 
  turn 
  brown, 
  and 
  soon 
  bo- 
  

   comes 
  of 
  a 
  bright 
  chestnut 
  color, 
  bearing 
  some 
  resemblance 
  to 
  a 
  flaxseed. 
  

  

  EFFECT 
  OF 
  THE 
  WORM 
  OR 
  LARVA 
  ON 
  THE 
  WHEAT. 
  

  

  As 
  has 
  been 
  stated, 
  the 
  worm 
  in 
  autumn 
  lies 
  at 
  the 
  sheathing 
  base 
  of 
  

   the 
  leaves 
  just 
  above 
  the 
  roots, 
  at 
  or 
  near 
  the 
  surface 
  of 
  the 
  soil. 
  It 
  is 
  

   easy 
  to 
  detect 
  the 
  flaxseed 
  from 
  its 
  large 
  size 
  and 
  chestnut-brown 
  color, 
  

   by 
  separating 
  the 
  leaf 
  from 
  the 
  stalk 
  of 
  the 
  young 
  wheat 
  in 
  October 
  

   and 
  November, 
  when 
  the 
  worm 
  has 
  stopped 
  feeding 
  and 
  is 
  incased 
  in 
  

   its 
  brown 
  sack. 
  Scattered 
  shoots 
  will 
  be 
  found, 
  withered 
  and 
  changed 
  

   to 
  a 
  light 
  yellow 
  color, 
  and, 
  as 
  Fitch 
  observes, 
  strongly 
  contrasting 
  with 
  

   the 
  rich 
  green 
  of 
  the 
  vigorous 
  uninjured 
  plants. 
  (See 
  Plate 
  IV, 
  represent- 
  

   ing 
  a 
  healthy 
  stalk 
  on 
  the 
  right 
  .and 
  a 
  dwarfed 
  plant 
  on 
  the 
  left, 
  con- 
  

   taining 
  three 
  flaxseeds, 
  with 
  the 
  leaves 
  partly 
  withered.) 
  The 
  worms, 
  

   before 
  assuming 
  the 
  flaxseed 
  state, 
  rest 
  between 
  the 
  leaves 
  and 
  the 
  

   stalk; 
  their 
  soft, 
  fleshy, 
  undeveloped 
  mouth 
  -parts 
  do 
  not 
  enable 
  them 
  to 
  

   gnaw 
  the 
  surface 
  of 
  the 
  plant, 
  but 
  the 
  sap 
  is 
  supi)osed 
  to 
  be 
  absorbed 
  

   directly 
  through 
  the 
  walls 
  of 
  the 
  body, 
  and 
  thus 
  they 
  are 
  said 
  to 
  feed 
  by 
  

   imbibition; 
  this 
  weakens 
  the 
  plant 
  and 
  causes 
  it 
  to 
  become 
  unhealthy 
  

   and 
  turn 
  yellow 
  and 
  die 
  ; 
  moreover, 
  although 
  this 
  point 
  is 
  disputed 
  by 
  

   Dr. 
  Fitch, 
  the 
  presence 
  of 
  the 
  worms 
  causes 
  the 
  formation 
  of 
  a 
  gall 
  like 
  

   swelling 
  or 
  enlargement 
  of 
  the 
  stalk, 
  an 
  abnormal 
  growth 
  of 
  the 
  plant 
  

   being 
  caused 
  by 
  the 
  slight 
  interruption 
  to 
  the 
  flow 
  of 
  the 
  sap. 
  Of 
  course 
  

   when 
  six 
  or 
  a 
  dozen 
  of 
  these 
  comparatively 
  large 
  flaxseeds 
  are 
  lodged 
  

   under 
  the 
  base 
  of 
  the 
  leaves 
  the 
  plant 
  turns 
  yellow 
  and 
  dies, 
  as 
  if 
  the 
  

   roots 
  had 
  been 
  aflected. 
  

  

  How 
  a 
  field 
  of 
  winter 
  wheat 
  may 
  be 
  attacked 
  and 
  affected 
  by 
  the 
  Hes- 
  

   sian 
  Fly 
  may 
  be 
  seen 
  by 
  reading 
  the 
  following 
  account 
  in 
  the 
  Cultivator 
  

   and 
  Country 
  Gentleman: 
  

  

  Last 
  fall 
  the 
  appearance 
  of 
  the 
  wheat 
  plant 
  on 
  different 
  fields 
  and 
  locations 
  was 
  

   very 
  different. 
  On 
  strong 
  and 
  level 
  lauds, 
  little 
  injury 
  was 
  shown. 
  Hilly 
  fields, 
  or 
  

  

  