﻿342 
  Mr. 
  F. 
  Enock's 
  life-history 
  of 
  

  

  waggon 
  goes, 
  there 
  the 
  puparia 
  are 
  shaken 
  out, 
  and 
  I 
  

   have 
  found 
  them 
  lying 
  free 
  on 
  the 
  ground 
  underneath 
  

   the 
  shocks 
  of 
  barley. 
  

  

  The 
  number 
  of 
  larvse 
  at 
  the 
  joints 
  varies 
  considerably 
  

   -^— 
  from 
  one 
  to 
  nine 
  in 
  straw 
  collected 
  at 
  Hertford, 
  and 
  in 
  

   home-grown 
  plants, 
  in 
  one 
  instance 
  only, 
  as 
  many 
  as 
  

   nineteen 
  ! 
  

  

  The 
  male 
  puparium 
  is 
  of 
  a 
  much 
  more 
  slender 
  form 
  

   and 
  paler 
  colour 
  than 
  that 
  of 
  the 
  female. 
  

  

  When 
  the 
  crop 
  of 
  barley 
  is 
  backward, 
  as 
  in 
  1888, 
  

   a 
  great 
  many 
  puparia 
  are 
  left 
  in 
  the 
  stubble, 
  and 
  should 
  

   the 
  field 
  be 
  sown 
  with 
  clover, 
  they 
  remain 
  in 
  the 
  stubble 
  

   all 
  the 
  winter, 
  secure 
  from 
  injury 
  ; 
  the 
  flies 
  which 
  

   emerge 
  after 
  the 
  harvest 
  have 
  no 
  difficulty 
  in 
  finding 
  

   plenty 
  of 
  aftergrowth 
  and 
  self-sown 
  plants 
  growing 
  

   among 
  the 
  clover, 
  and 
  on 
  which 
  they 
  lay 
  their 
  eggs. 
  

  

  Owing 
  to 
  the 
  time 
  of 
  year 
  when 
  the 
  wheat 
  and 
  barley 
  

   are 
  sown, 
  the 
  females 
  are 
  all 
  dead 
  before 
  the 
  wheat 
  is 
  up 
  ; 
  

   but 
  not 
  so 
  in 
  America, 
  where 
  whole 
  districts 
  of 
  "fall- 
  

   wheat" 
  are 
  entirely 
  ruined. 
  

  

  On 
  Dec. 
  31st, 
  1888, 
  I 
  received 
  from 
  America 
  a 
  tin 
  box 
  

   which 
  contained 
  a 
  large 
  number 
  of 
  plants 
  of 
  this 
  " 
  fall- 
  

   wheat," 
  a 
  very 
  slight 
  examination 
  of 
  which 
  revealed 
  a 
  

   number 
  of 
  puparia 
  close 
  round 
  the 
  base 
  of 
  the 
  stem, 
  and 
  

   in 
  some 
  cases 
  there 
  was 
  a 
  slight 
  appearance 
  of 
  a 
  gall- 
  

   like 
  swelling. 
  I 
  put 
  these 
  plants 
  under 
  a 
  cylinder 
  of 
  

   muslin, 
  and 
  exposed 
  them 
  to 
  the 
  full 
  force 
  of 
  the 
  weather. 
  

   From 
  May 
  5th 
  to 
  the 
  22nd 
  I 
  bred 
  forty-four 
  male 
  and 
  

   thirty-seven 
  female 
  Hessian 
  Flies, 
  and 
  from 
  Jmie 
  5th 
  to 
  

   July 
  5th 
  twenty-three 
  parasites, 
  Platygaster 
  minutus. 
  

  

  Herr 
  Wagner, 
  in 
  his 
  admirable 
  Monograph 
  on 
  the 
  

   Hessian 
  Fly 
  (a 
  translation 
  of 
  which 
  appears 
  in 
  the 
  

   Appendix 
  to 
  the 
  'Third 
  Eeport 
  of 
  the 
  U. 
  S. 
  A. 
  Entomo- 
  

   logical 
  Commission'), 
  states 
  that: 
  — 
  "Though 
  the 
  great 
  

   frequency 
  of 
  the 
  parasites 
  in 
  the 
  summer 
  generation 
  was 
  

   striking, 
  it 
  was 
  not 
  less 
  so 
  that 
  the 
  pup^ 
  gathered 
  from 
  

   the 
  barley 
  aftergrowth 
  yielded 
  not 
  a 
  smgle 
  parasite, 
  

   from 
  which 
  I 
  infer 
  an 
  entire 
  exemption 
  of 
  the 
  actual 
  

   winter 
  generation 
  (not 
  to 
  be 
  mistaken 
  for 
  those 
  hj^ber- 
  

   nating 
  in 
  stubble) 
  from 
  parasites. 
  Fitch 
  received 
  from 
  

   young 
  infested 
  plants 
  gathered 
  in 
  April 
  only 
  gall-gnats, 
  

   thus 
  corroborating 
  my 
  idea 
  that 
  the 
  parasites 
  attack 
  only 
  

   the 
  winter 
  generation." 
  

  

  I 
  venture 
  to 
  think 
  that 
  Herr 
  Wagner 
  did 
  not 
  obtain 
  a 
  

   sufficiently 
  large 
  number 
  of 
  plants, 
  or 
  he 
  would 
  no 
  doubt 
  

  

  