﻿230 
  REPORT 
  UNITED 
  STATES 
  ENTOMOLOGICAL 
  COMMISSION. 
  

  

  was 
  cut, 
  and 
  the 
  eggs 
  or 
  larvse 
  were 
  found 
  above 
  the 
  first 
  or 
  second 
  joint. 
  The 
  dam- 
  

   age 
  on 
  five 
  acres 
  of 
  wheat 
  was 
  prohably 
  five 
  or 
  six 
  bushels. 
  By 
  reaping 
  low 
  and 
  

   raking 
  the 
  stubble 
  was 
  all 
  saved." 
  

  

  A 
  serious 
  objection 
  to 
  reaping 
  low 
  is 
  tliat 
  many 
  insects 
  of 
  tlie 
  summer 
  

   brood 
  in 
  the 
  flaxseed 
  state 
  are, 
  as 
  Mr. 
  S. 
  S. 
  Rathvon 
  claims, 
  carried 
  to 
  the 
  

   barn 
  or 
  stack, 
  beyond 
  the 
  reach 
  of 
  remedy. 
  From 
  the 
  straw 
  thus 
  har- 
  

   vested 
  the 
  fly 
  would 
  emerge 
  before 
  it 
  was 
  threshed, 
  ''and 
  might 
  even 
  

   pass 
  through 
  a 
  machine 
  without 
  injury." 
  In 
  this 
  manner 
  the 
  fly 
  has 
  

   possibly 
  been 
  distributed 
  through 
  different 
  sections 
  of 
  the 
  country. 
  

  

  Burning 
  the 
  stubhle.^ 
  — 
  Although 
  this 
  remedy 
  has 
  been 
  advocated, 
  it 
  

   will 
  be 
  seen 
  to 
  be 
  worse 
  than 
  useless 
  when 
  we 
  reflect 
  that 
  after 
  all 
  the 
  

   artificial 
  means 
  taken 
  to 
  reduce 
  the 
  number 
  of 
  the 
  Hessian 
  Fly, 
  nature's 
  

   method 
  of 
  checking 
  its 
  undue 
  increase 
  is 
  far 
  more 
  important 
  and 
  

   thorough-going; 
  we 
  refer 
  to 
  the 
  diffusion 
  and 
  multiplication 
  of 
  the 
  

   insect-parasites. 
  As 
  previously 
  stated, 
  most 
  probably 
  nine-tenths 
  of 
  

   the 
  young 
  Hessian 
  Flies 
  are 
  destroyed 
  in 
  the 
  larva 
  or 
  pupa 
  state 
  by 
  

   the 
  parasites 
  already 
  described. 
  For 
  the 
  most 
  part 
  these 
  parasites 
  

   live 
  in 
  the 
  flaxseeds 
  contained 
  in 
  the 
  straw, 
  and 
  appear 
  in 
  spring. 
  Now, 
  

   to 
  burn 
  the 
  stubble 
  in 
  the 
  autumn 
  or 
  early 
  spring 
  is 
  simply 
  to 
  destroy 
  

   these 
  useful 
  parasites, 
  the 
  best 
  friends 
  of 
  the 
  farmer. 
  We 
  do 
  not 
  hesi- 
  

   tate 
  to 
  urge 
  that 
  the 
  straw 
  be 
  untouched. 
  On 
  the 
  contrary, 
  the 
  para- 
  

   sites 
  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 
  disseminating 
  the 
  parasites 
  their 
  noxious 
  hosts 
  may 
  increase 
  and 
  be 
  

   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 
  transformations, 
  

   become 
  fledged, 
  and 
  ready, 
  when 
  the 
  eggs 
  and 
  larvae 
  of 
  the 
  Hessian 
  FI3' 
  

   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 
  favorable 
  to 
  the 
  

   corresponding 
  increase 
  in 
  the 
  number 
  of 
  their 
  insect 
  or 
  ichneumon 
  para- 
  

   sites; 
  they 
  do 
  their 
  work 
  so 
  effectively 
  that 
  the 
  few 
  following 
  years 
  the 
  

   numbers 
  of 
  Hessian 
  Flies 
  are 
  greatlj^ 
  reduced. 
  It 
  is, 
  then, 
  to 
  these 
  

   parasites 
  that 
  we 
  are 
  indebted 
  for 
  the 
  year^of 
  immunity 
  from 
  the 
  at 
  

   tacks 
  of 
  the 
  Hessian 
  Fly, 
  as 
  much 
  as 
  to 
  fiivorable 
  or 
  unfavorable 
  

   weather, 
  and 
  this 
  leads 
  us 
  to 
  consider 
  the 
  apparent 
  periodicity 
  in 
  the 
  

   years 
  of 
  abundance 
  and 
  scarcity 
  of 
  the 
  Hessian 
  Fly. 
  

  

  PERIODICITY 
  IN 
  THE 
  ABUNDANCE 
  AND 
  SCARCITY 
  OF 
  THE 
  HESSIAN 
  

  

  FLY. 
  

  

  The 
  following 
  tabular 
  view, 
  though 
  constructed 
  from 
  very 
  scanty 
  and 
  

   often 
  misleading 
  data, 
  may 
  throw 
  some 
  light 
  on 
  this 
  subject. 
  

   The 
  table 
  has 
  been 
  drawn 
  up 
  from 
  the 
  reports 
  of 
  Fitch, 
  Hind, 
  Cook,, 
  

  

  