﻿WAGNER 
  ON 
  THE 
  HESSIAN 
  FLY. 
  [17] 
  

  

  do 
  the 
  flies 
  deposit 
  their 
  eggs 
  before 
  the 
  appearance 
  of 
  the 
  winter 
  croi) 
  ? 
  

   As 
  I 
  looked 
  for 
  a 
  long 
  time 
  in 
  vain 
  for 
  the 
  maggots 
  of 
  this 
  hard-pressed 
  

   insect, 
  I 
  was 
  about 
  leaving 
  the 
  greater 
  part 
  of 
  the 
  brood 
  pitilessly 
  to 
  

   its 
  fate; 
  but 
  I 
  was 
  very 
  soon 
  convinced 
  of 
  my 
  mistake. 
  As 
  is 
  well 
  known, 
  

   the 
  farmer, 
  to 
  his 
  sorrow, 
  often 
  observes 
  on 
  the 
  barley 
  that, 
  in 
  harvest 
  

   time, 
  the 
  greater 
  quantity 
  of 
  the 
  straw 
  breaks 
  a 
  little 
  below 
  the 
  ear, 
  

   which 
  soon 
  disseminates 
  its 
  couteuts 
  or 
  drops 
  oft* 
  entirely. 
  If 
  the 
  soil 
  

   is 
  loose 
  and 
  rich 
  in 
  humus, 
  it 
  will 
  cover 
  itself, 
  especially 
  when 
  fiivored 
  

   with 
  some 
  rain, 
  in 
  a 
  short 
  time 
  with 
  young 
  sprouts, 
  often 
  attaining 
  consid- 
  

   erable 
  growth 
  in 
  the 
  late 
  fall, 
  and 
  these 
  I, 
  as 
  they 
  appear 
  after 
  harvest- 
  

   ing, 
  will 
  briefly 
  call 
  "barley 
  aftergrowth." 
  And 
  indeed 
  our 
  flies 
  have 
  

   chosen 
  this 
  "aftergrowth," 
  being 
  pressed 
  to 
  oviposition, 
  and 
  attacked 
  

   especially 
  those 
  fields 
  in 
  whose 
  immediate 
  neighborhood 
  the 
  maggots 
  

   previously 
  appeared 
  in 
  numbers, 
  so 
  that 
  not 
  a 
  single 
  stalk 
  remained.* 
  

  

  Owing 
  to 
  this 
  interesting 
  discovery 
  at 
  the 
  end 
  of 
  November 
  I 
  gave 
  up 
  

   the 
  further 
  examination 
  of 
  the 
  maggots 
  occurring 
  in 
  rye, 
  and 
  followed 
  all 
  

   the 
  more 
  diligently 
  the 
  development 
  of 
  the 
  easy 
  obtainable 
  material 
  

   on 
  the 
  so-called 
  aftergrowth. 
  The 
  mild 
  first 
  part 
  of 
  December 
  favored 
  

   me 
  in 
  finding 
  the 
  maggots. 
  I 
  shall 
  now 
  allude 
  to 
  the 
  developmental 
  

   stages 
  of 
  the 
  maggots, 
  which 
  however 
  appeared 
  more 
  near 
  each 
  other 
  

   than 
  after 
  each 
  other. 
  

  

  The 
  maggots 
  discarded 
  their 
  former, 
  more 
  stretched, 
  nearly 
  cylindri- 
  

   cal 
  form, 
  the 
  shai^e 
  now 
  again 
  approaching 
  the 
  originally 
  elongate 
  egg- 
  

   form 
  of 
  the 
  earliest 
  state. 
  This 
  more 
  robust 
  look 
  was 
  evidently 
  due 
  to 
  

   the 
  considerable 
  development 
  of 
  the 
  adipose 
  body, 
  which 
  in 
  most 
  of 
  the 
  

   specimens 
  was 
  distinguishable 
  as 
  a 
  snow-white 
  mass 
  from 
  the 
  remain- 
  

   der 
  of 
  the 
  more 
  transparent 
  body. 
  The 
  segmentation 
  was 
  less 
  distinct 
  

   than 
  in 
  the 
  formerly 
  examined 
  maggots, 
  as 
  the 
  sides 
  scarcely 
  showed 
  any 
  

   emarginations. 
  Viewed 
  from 
  above, 
  the 
  head 
  of 
  the 
  maggot 
  seemed 
  to 
  

   have 
  disai)peared, 
  allowing 
  but 
  twelve 
  segments 
  to 
  be 
  counted; 
  on 
  the' 
  

   ventral 
  side 
  of 
  the 
  first 
  thoracic 
  segment 
  the 
  first 
  cephalic 
  ring 
  was 
  rep- 
  

   resented 
  by 
  a 
  small 
  protuberance, 
  and 
  the 
  posterior 
  segment 
  was 
  suf- 
  

   ficiently 
  indicated 
  by 
  a 
  shallow 
  groove, 
  which 
  usually 
  connected 
  with, 
  

   the 
  suture 
  between 
  the 
  first 
  two 
  thoracic 
  rings. 
  

  

  In 
  the 
  least 
  developed 
  maggots 
  the 
  yellowish-white 
  adipose 
  body 
  ap- 
  

   peared 
  on 
  both 
  sides 
  in 
  connecting 
  portions, 
  so 
  that 
  transparent 
  por- 
  

   tions 
  could 
  be 
  seen 
  only 
  in 
  the 
  vertical 
  line 
  of 
  the 
  longitudinal 
  axis, 
  in. 
  

   which 
  portions 
  the 
  greenish 
  contents 
  of 
  the 
  intestine 
  were 
  visible. 
  Sev- 
  

   eral 
  times 
  in 
  placing 
  such 
  a 
  maggot 
  in 
  a 
  drop 
  of 
  water, 
  tenderly 
  strok- 
  

   ing 
  it 
  with 
  a 
  camel's 
  hair 
  pencil, 
  a 
  number 
  of 
  green 
  corpuscles 
  soon 
  

   swam 
  in 
  the 
  water, 
  evidently 
  issuing 
  from 
  the 
  intestine 
  of 
  the 
  maggot. 
  

   I 
  take 
  these 
  corpuscles 
  to 
  be 
  chlorophyll 
  granules 
  which 
  the 
  maggot 
  

   takes 
  in 
  with 
  the 
  cellular 
  juice. 
  Experience 
  that 
  the 
  green 
  intestinal 
  

   contents 
  of 
  such 
  alcoholic 
  specimens 
  decolorizes 
  strengthens 
  me 
  in 
  this 
  

   belief. 
  I 
  did 
  not 
  succeed 
  by 
  any 
  means 
  in 
  compelling 
  the 
  maggots 
  re- 
  

   ferred 
  to 
  to 
  i)rotrude 
  the 
  invaginated 
  head. 
  As 
  the 
  maggot 
  undoubtedly 
  

   still 
  takes 
  nourishment 
  in 
  this 
  developmental 
  phase, 
  but 
  closely 
  ap- 
  

   proaches 
  its 
  full 
  growth, 
  it 
  is 
  assumed 
  that 
  the 
  retraction 
  of 
  the 
  head 
  

   takes 
  place 
  at 
  the 
  moment 
  of 
  separating 
  it 
  from 
  the 
  plant, 
  and 
  that 
  in 
  

   the 
  extremely 
  slow 
  maggot, 
  when 
  once 
  disturbed 
  in 
  its 
  life-habit, 
  the 
  

   assumed 
  condition 
  is 
  retained. 
  

  

  A 
  second 
  portion 
  of 
  maggots 
  distinguishes 
  itself 
  by 
  the 
  entire 
  want 
  

  

  * 
  That 
  the 
  aftergrowth 
  has 
  snch 
  a 
  great 
  attraction 
  for 
  the 
  flies 
  of 
  neighboring 
  infested 
  fieldvS, 
  aspecial 
  

   case 
  taught 
  me 
  : 
  On 
  a 
  field 
  of 
  baile.> 
  on 
  which 
  I 
  previously 
  could 
  see 
  no 
  trace 
  of 
  the 
  insect 
  the 
  mag- 
  

   gots 
  appeared 
  very 
  numerous 
  in 
  the 
  aftergrowth. 
  

  

  2 
  AP 
  E 
  

  

  