﻿126 
  REPOET 
  UNITED 
  STATES 
  ENTOMOLOGICAL 
  COMMISSION. 
  

  

  The 
  Eed-tailed 
  Tachina 
  fly 
  {Nemorma 
  leucan[i]ce^ 
  Kirkpatrick, 
  Plate 
  

   I, 
  Fig. 
  7) 
  and 
  tlie 
  Yellow-tailed 
  Tachina 
  fly 
  [Exorista 
  flavicauda 
  Eiley, 
  

   Plate 
  I, 
  Fig. 
  6) 
  are 
  known 
  to 
  infest 
  it. 
  Seizing 
  the 
  first 
  opportunity 
  

   to 
  attach 
  their 
  eggs 
  behind 
  the 
  heads 
  of 
  the 
  Army 
  Worms, 
  these 
  flies 
  

   are 
  as 
  persistent 
  in 
  their 
  work 
  of 
  destruction 
  as 
  the 
  worms 
  are 
  rest- 
  

   less 
  under 
  attack. 
  As 
  many 
  as 
  eighteen 
  eggs 
  of 
  the 
  Eed-tailed 
  Tachina 
  

   are 
  sometimes 
  deposited 
  upon 
  a 
  single 
  worm, 
  but 
  the 
  average 
  is 
  about 
  

   five. 
  These 
  eggs 
  are 
  almost 
  without 
  exception 
  placed 
  upon 
  the 
  head 
  

   or 
  thorax 
  of 
  the 
  worm, 
  so 
  that 
  the 
  latter 
  cannot 
  reach 
  them 
  with 
  its 
  

   jaws. 
  Occasionally, 
  however, 
  they 
  are 
  placed 
  upon 
  the 
  first 
  abdo- 
  

   minal 
  segment, 
  and 
  one 
  worm, 
  now 
  in 
  the 
  collection 
  of 
  the 
  Department, 
  

   carries 
  one 
  Tachina 
  eigg 
  upon 
  the 
  third 
  abdominal 
  segment 
  and 
  one 
  

   upon 
  the 
  eighth. 
  From 
  eight 
  per 
  cent, 
  upwards 
  of 
  the 
  worms 
  in 
  an 
  

   infested 
  field 
  have 
  frequently 
  been 
  noticed 
  to 
  carry 
  the 
  eggs 
  of 
  these 
  

   Tachina 
  flies, 
  which, 
  though 
  rendering 
  the 
  most 
  efficient 
  service 
  to 
  the 
  

   farmer, 
  are 
  not 
  unfrequently 
  supposed 
  by 
  him 
  to 
  be 
  the 
  parent 
  and 
  

   cause 
  of 
  the 
  worm.^^ 
  

  

  We 
  have 
  observed, 
  since 
  the 
  publication 
  of 
  our 
  Bulletin 
  No. 
  3 
  of 
  the 
  

   United 
  States 
  Entomological 
  Commission, 
  in 
  the 
  case 
  of 
  the 
  Cotton 
  

   Worm, 
  that, 
  contrary 
  to 
  the 
  former 
  belief^ 
  the 
  presence 
  of 
  these 
  eggs 
  on 
  

   the 
  back 
  of 
  a 
  worm 
  does 
  not 
  necessarily 
  indicate 
  a 
  sure 
  death, 
  although 
  

   in 
  the 
  vast 
  majority 
  of 
  cases 
  it 
  Undoubtedly 
  does. 
  Mr. 
  Coquillett 
  ex- 
  

   perimented 
  upon 
  this 
  point 
  with 
  the 
  following 
  result: 
  Of 
  sixty-six 
  

   Army 
  Worms, 
  each 
  bearing 
  from 
  one 
  to 
  five 
  eggs 
  of 
  the 
  Tachina, 
  four 
  

   transformed 
  to 
  pupae, 
  from 
  three 
  of 
  which 
  the 
  moths 
  issued. 
  The 
  re- 
  

   maining 
  sixty 
  -two 
  were 
  killed, 
  and 
  from 
  them 
  issued 
  one 
  hundred 
  and 
  

   four 
  Tachina 
  larvae, 
  sixty-one 
  of 
  which 
  successfully 
  transformed 
  to 
  

   flies. 
  ^° 
  

  

  Next, 
  perhaps, 
  in 
  importance 
  to 
  the 
  Tachina 
  flies 
  come 
  the 
  Microgas- 
  

   ters, 
  minute 
  four- 
  winged 
  flies, 
  of 
  which 
  there 
  are 
  several 
  species 
  parasitic 
  

   upon 
  the 
  Army 
  Worm. 
  Their 
  larvae 
  live 
  within 
  the 
  body 
  of 
  the 
  host, 
  

   and, 
  issuing, 
  spin 
  small, 
  oval, 
  silken 
  cocoons 
  attached 
  by 
  loose 
  silk 
  to 
  

   some 
  neighboring 
  object. 
  

  

  Walsh 
  described 
  the 
  most 
  abundant 
  of 
  these 
  species 
  in 
  1861 
  under 
  

   the 
  name 
  of 
  Microgaster 
  (Apanteles) 
  militaris. 
  (PI. 
  II, 
  Fig. 
  6.) 
  This 
  spe- 
  

   cies 
  is 
  found 
  wherever 
  the 
  Army 
  Worms 
  are 
  abundant, 
  and 
  its 
  white 
  

   cocoons, 
  attached 
  to 
  the 
  grass 
  or 
  to 
  the 
  under 
  side 
  of 
  stones 
  and 
  sticks 
  

   about 
  the 
  field, 
  are 
  sometimes 
  so 
  numerous 
  as 
  to 
  make 
  the 
  ground 
  look 
  

   whitish 
  in 
  spots. 
  These 
  cocoons 
  are 
  invariably 
  found 
  in 
  small 
  masses 
  

   surrounded 
  by 
  more 
  or 
  less 
  loose 
  silk. 
  The 
  adult 
  fly 
  is 
  black, 
  with 
  

   rufous 
  legs. 
  It 
  was 
  the 
  cocoons 
  of 
  this 
  insect 
  which 
  gave 
  the 
  founda- 
  

  

  89 
  "In 
  1875 
  no 
  leas 
  than 
  four 
  of 
  our 
  correspondents 
  exiiressed 
  a 
  belief 
  that, 
  in 
  the 
  language 
  of 
  one 
  of 
  

   them, 
  the 
  woitqs 
  came 
  from 
  a 
  dark 
  -colored 
  buzzing 
  fly 
  about 
  the 
  size 
  of 
  a 
  blow-fly, 
  which 
  is 
  noticed 
  

   around 
  old 
  stack-yards 
  just 
  before 
  the 
  worms 
  come 
  ; 
  and 
  -when 
  plentiful, 
  the 
  Army 
  Worm 
  is 
  sure 
  to 
  

   follow." 
  

  

  *<»For 
  descriptions 
  of 
  these 
  flies 
  see 
  Prairie 
  Farmer, 
  vol. 
  VIII; 
  Second 
  Missouri 
  Entomological 
  Re- 
  

   port, 
  and 
  Eighth 
  Missouri 
  Entomological 
  Report. 
  

  

  