﻿364 
  Mr. 
  F. 
  Enock's 
  life-history 
  of 
  

  

  larva 
  or 
  pupa 
  state 
  by 
  the 
  parasites 
  already 
  described. 
  

   For 
  the 
  most 
  part, 
  these 
  parasites 
  live 
  in 
  the 
  ' 
  flax-seed' 
  

   contained 
  in 
  the 
  straw, 
  and 
  appear 
  in 
  spring. 
  Now, 
  to 
  

   burn 
  the 
  stubble 
  in 
  the 
  autumn 
  or 
  early 
  spring 
  is 
  sim})!}' 
  

   to 
  destroy 
  these 
  useful 
  parasites, 
  the 
  best 
  friends 
  of 
  the 
  

   farmer. 
  We 
  do 
  not 
  hesitate 
  to 
  urge 
  that 
  the 
  straw 
  be 
  

   untouched. 
  On 
  the 
  contrary, 
  the 
  parasites 
  should 
  be 
  

   gathered 
  and 
  bred 
  in 
  numbers, 
  and 
  we 
  believe 
  that 
  

   practical 
  entomologists 
  should 
  bend 
  all 
  their 
  energies 
  

   towards 
  clearing 
  up 
  the 
  subject 
  of 
  rearing 
  and 
  multiplying 
  

   these 
  insect 
  hosts. 
  Much 
  knowledge 
  and 
  practical 
  skill 
  

   is 
  needed 
  in 
  this 
  direction, 
  as 
  occasionally 
  by 
  dissemi- 
  

   nating 
  the 
  parasites 
  their 
  noxious 
  hosts 
  may 
  be 
  increased 
  

   and 
  distributed 
  ; 
  but 
  knowing, 
  as 
  we 
  do, 
  how 
  many 
  more 
  

   of 
  the 
  parasites 
  are 
  in 
  many 
  cases 
  bred 
  than 
  the 
  insects 
  

   on 
  which 
  they 
  prey, 
  it 
  seems 
  safe 
  and 
  reasonable 
  to 
  

   advise 
  not 
  only 
  not 
  burning 
  the 
  stubble, 
  but 
  letting 
  it 
  

   stand, 
  so 
  that 
  the 
  parasites 
  may 
  finish 
  their 
  transforma- 
  

   tions, 
  become 
  fledged, 
  and 
  ready, 
  when 
  the 
  eggs 
  and 
  

   larvae 
  of 
  the 
  Hessian 
  Fly 
  are 
  upon 
  or 
  in 
  the 
  young 
  

   wheat, 
  to 
  destroy 
  them. 
  It 
  is 
  a 
  matter 
  of 
  fact 
  that 
  in 
  

   years 
  when 
  the 
  Hessian 
  Fly 
  is 
  specially 
  abundant 
  and 
  

   destructive, 
  similar 
  seasons 
  are 
  highly 
  favourable 
  to 
  the 
  

   corresponding 
  increase 
  in 
  the 
  number 
  of 
  then* 
  insect 
  or 
  

   ichneumon 
  parasites 
  ; 
  they 
  do 
  their 
  work 
  so 
  effectuall}^ 
  

   that 
  the 
  few 
  following 
  years 
  the 
  numbers 
  of 
  Hessian 
  

   Flies 
  are 
  greatly 
  reduced. 
  It 
  is, 
  then, 
  to 
  these 
  parasites 
  

   that 
  we 
  are 
  indebted 
  for 
  the 
  years 
  of 
  immunity 
  from 
  the 
  

   the 
  attacks 
  of 
  the 
  Hessian 
  Fly 
  as 
  much 
  as 
  to 
  favom'able 
  

   and 
  unfavourable 
  weather." 
  

  

  Herr 
  Wagner 
  also 
  states 
  that, 
  " 
  The 
  most 
  effectual 
  

   remedy 
  in 
  checking 
  the 
  excessive 
  multiplication 
  of 
  the 
  

   wheat-worm 
  has 
  been 
  provided 
  by 
  Nature 
  herself 
  in 
  the 
  

   aid 
  received 
  from 
  the 
  parasites 
  just 
  mentioned. 
  To 
  spare 
  

   them 
  is 
  a 
  very 
  important 
  thing." 
  

  

  On 
  July 
  30th, 
  1888, 
  I 
  ventured 
  to 
  bring 
  the 
  subject 
  of 
  

   breeding 
  the 
  parasites 
  before 
  the 
  readers 
  of 
  the 
  ' 
  Mark 
  

   Lane 
  Express,' 
  for 
  since 
  ni}^ 
  letter 
  to 
  ' 
  The 
  Times' 
  I 
  had 
  

   had 
  another 
  year's 
  practical 
  experience 
  of 
  rearing 
  para- 
  

   sites, 
  so 
  could 
  speak 
  still 
  more 
  positively 
  as 
  to 
  what 
  

   could 
  be 
  done. 
  This 
  letter 
  was 
  replied 
  to 
  in 
  the 
  followmg 
  

   week, 
  Aug. 
  6th, 
  but 
  in 
  a 
  totally 
  difl'erent 
  manner 
  to 
  what 
  

   might 
  have 
  been 
  expected. 
  I 
  was 
  told, 
  "I 
  was 
  no 
  

   farmer": 
  that 
  "there 
  were 
  other 
  diiSculties 
  in 
  the 
  

  

  