﻿[34] 
  REPORT 
  UNITED 
  STATES 
  ENTOMOLOGICAL 
  COMMISSION. 
  

  

  ficial 
  examination 
  they 
  belong 
  to 
  five 
  species, 
  amongst 
  which 
  are 
  three 
  

   in 
  which 
  always 
  but 
  one 
  insect 
  issues; 
  in 
  the 
  other 
  two 
  species, 
  compris- 
  

   ing 
  the 
  smallest 
  species, 
  there 
  are 
  always 
  from 
  three 
  to 
  five 
  specimens 
  

   in 
  one 
  shell. 
  Those 
  obtained 
  from 
  wheat 
  stubble 
  issued 
  in 
  the 
  time 
  

   between 
  April 
  18 
  and 
  May 
  30. 
  Two 
  of 
  these 
  are 
  identical 
  with 
  those 
  

   that 
  had 
  already 
  come 
  forth 
  in 
  autumn. 
  The 
  third 
  species, 
  which 
  I 
  several 
  

   times 
  found 
  in 
  such 
  immense 
  numbers 
  in 
  April 
  and 
  May 
  on 
  a 
  field 
  of 
  

   clover 
  with 
  stubble, 
  so 
  that 
  one 
  within 
  a 
  short 
  time 
  could 
  have 
  easily 
  

   gathered 
  several 
  hundred 
  specimens, 
  is 
  characterized 
  by 
  its 
  deep 
  black 
  

   color. 
  From 
  these 
  three, 
  too, 
  but 
  one 
  specimen 
  comes 
  forth 
  from 
  one 
  

   Cecidomyia 
  maggot. 
  Where 
  those 
  parasites 
  issuing 
  in 
  fall 
  hibernate 
  

   I 
  could 
  not 
  accurately 
  find 
  out; 
  scarcely 
  in 
  the 
  stubble, 
  because 
  there 
  

   I 
  never 
  found 
  one 
  of 
  the 
  ichneumons 
  ; 
  they 
  may 
  hibernate 
  in 
  the 
  soiL 
  

   To 
  what 
  the 
  attacks 
  of 
  the 
  parasites 
  are 
  directed, 
  whether 
  on 
  eggs 
  or 
  

   maggots, 
  or 
  probably 
  on 
  both, 
  requires 
  to 
  be 
  investigated. 
  That 
  at 
  

   least 
  one 
  or 
  several 
  species 
  pierce 
  the 
  egg 
  is 
  presumed, 
  as 
  I 
  repeatedly 
  

   found 
  pupae 
  of 
  the 
  parasites 
  already 
  in 
  the 
  beginning 
  of 
  July 
  in 
  the 
  

   gall-gnat 
  maggots. 
  Dissections 
  made 
  in 
  the 
  fall 
  on 
  numerous 
  pseudo- 
  

   pupae 
  showed 
  that 
  60 
  to 
  70 
  per 
  cent, 
  of 
  the 
  insects 
  contained 
  parasites* 
  

   Though 
  the 
  great 
  frequency 
  of 
  the 
  parasites 
  on 
  the 
  summer 
  genera- 
  

   tion 
  was 
  striking, 
  it 
  was 
  not 
  less 
  so 
  that 
  the 
  pupae 
  gathered 
  from 
  barley 
  

   aftergrowth 
  yielded 
  not 
  a 
  single 
  parasite 
  ; 
  from 
  which 
  I 
  infer 
  an 
  entire 
  

   exemption 
  of 
  the 
  actual 
  winter 
  generation 
  (not 
  to 
  be 
  mistaken 
  for 
  those 
  

   hibernating 
  on 
  stubble) 
  from 
  parasites. 
  Fitch 
  received 
  from 
  young 
  in- 
  

   fested 
  plants 
  gathered 
  in 
  April 
  only 
  gall-gnats, 
  thus 
  corroborating 
  my 
  

   idea 
  that 
  the 
  parasites 
  attack 
  only 
  the 
  summer 
  generation. 
  

  

  §10. 
  — 
  Eemedies. 
  

  

  The 
  most 
  effective 
  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. 
  All 
  considerations 
  and 
  restrictions 
  offered 
  relative 
  to 
  the 
  mode 
  

   of 
  life 
  of 
  the 
  parasites 
  apply 
  to 
  the 
  choice 
  of 
  the 
  means 
  of 
  destroying 
  

   the 
  summer 
  generation 
  rather 
  than 
  the 
  winter 
  generation, 
  as 
  the 
  latter 
  

   does 
  not, 
  as 
  far 
  as 
  is 
  known, 
  harbor 
  any 
  parasites. 
  

  

  Loew, 
  in 
  his 
  memoir, 
  has 
  dwelt 
  at 
  length 
  on 
  the 
  principles 
  regarding 
  

   the 
  choice 
  of 
  remedies^ 
  mentioning 
  first 
  the 
  direct 
  and 
  then 
  the 
  indirect 
  

   remedies. 
  I 
  will 
  also 
  begin 
  with 
  the 
  direct 
  remedies. 
  

  

  1. 
  Removal 
  of 
  the 
  barley 
  aftergrowth, 
  

  

  I 
  mentioned 
  in 
  § 
  3, 
  2 
  the 
  aftergrowth 
  produced 
  from 
  self-sown 
  

   barley, 
  and 
  showed 
  what 
  an 
  important 
  role 
  it 
  plays 
  in 
  the 
  natural 
  

   history 
  of 
  our 
  iosect. 
  Unequal 
  maturation 
  of 
  the 
  ears, 
  wind, 
  and 
  pour- 
  

   ing 
  rain 
  favor 
  the 
  falling 
  out 
  of 
  the 
  seeds, 
  taking 
  its 
  appearance 
  in 
  

   certain 
  years 
  almost 
  general, 
  while 
  it 
  occurs 
  less 
  frequently 
  in 
  dry, 
  quiet 
  

   summers 
  ; 
  but 
  it 
  will 
  never 
  be 
  missed 
  in 
  any 
  year. 
  On 
  fields 
  with 
  young 
  

   clover, 
  whjere 
  the 
  barley-drop 
  is 
  protected 
  from 
  seed-eating 
  (sperm- 
  

   ophagous) 
  animals 
  (birds, 
  sheep), 
  and 
  soon 
  germinates, 
  on 
  account 
  of 
  the 
  

   more 
  persistent 
  moisture 
  in 
  the 
  soil, 
  the 
  aftergrowth 
  is 
  most 
  striking. 
  

   It 
  is 
  this 
  young 
  barley 
  growth 
  which 
  our 
  fly 
  visits 
  for 
  the 
  purpose 
  

   of 
  ovipositing 
  before 
  the 
  appearance 
  of 
  rye 
  and 
  wheat. 
  The 
  consider- 
  

   able 
  number 
  of 
  maggots, 
  as 
  found 
  by 
  me, 
  is 
  explained 
  by 
  the 
  circum- 
  

   stance 
  that 
  the 
  swarming 
  of 
  the 
  fly 
  occurs 
  at 
  a 
  time 
  when 
  the 
  fields 
  

   lack 
  any 
  other 
  green 
  crops. 
  We 
  find 
  here 
  the 
  enemy 
  on 
  a 
  soil 
  which 
  

  

  