﻿19.— 
  NOTE 
  ON 
  A 
  BRACONID 
  PARASITE 
  OF 
  AGROTIS 
  YPSILON. 
  

   (Plates 
  XXVII-XXVIII). 
  

  

  By 
  H. 
  L. 
  DuTT, 
  B.A., 
  M.Sc.A. 
  (Cornell), 
  Officiating 
  Economic 
  Botanist, 
  

  

  Bihar 
  and 
  Orissa. 
  

  

  Agrotis 
  ypsilon, 
  Rott., 
  which 
  is 
  a 
  very 
  serious 
  pest 
  of 
  the 
  Rahi 
  crops 
  

   in 
  some 
  of 
  the 
  chaur 
  lands 
  in 
  the 
  Province 
  of 
  Bihar 
  and 
  Orissa, 
  has 
  

   several 
  parasites, 
  none 
  of 
  which 
  under 
  natural 
  conditions 
  can 
  keep 
  

   the 
  pest 
  under 
  control, 
  on 
  account 
  of 
  the 
  adverse 
  conditions 
  obtaining 
  

   in 
  the 
  areas 
  concerned. 
  Of 
  these, 
  the 
  most 
  common 
  is 
  a 
  Braconid, 
  

   probably 
  a 
  Microgaster 
  sp., 
  which 
  is 
  much 
  in 
  evidence 
  in 
  the 
  destructive 
  

   second 
  brood 
  of 
  the 
  caterpillar 
  pest, 
  when 
  it 
  is 
  too 
  late 
  to 
  be 
  of 
  any 
  

   real 
  benefit 
  to 
  the 
  crop, 
  since 
  by 
  the 
  time 
  an 
  affected 
  brood 
  of 
  caterpillars 
  

   succumbs 
  to 
  the 
  attack 
  of 
  the 
  parasite 
  the 
  damage 
  to 
  the 
  crop 
  has 
  

   already 
  been 
  done. 
  For 
  the 
  last 
  two 
  years 
  a 
  considerable 
  amount 
  of 
  

   work 
  has 
  been 
  done 
  on 
  this 
  parasite, 
  in 
  the 
  Insectary 
  at 
  Sabour, 
  with 
  

   a 
  view 
  to 
  finding 
  out 
  if 
  it 
  is 
  possible 
  to 
  utilise 
  it 
  as 
  a 
  means 
  of 
  control 
  of 
  

   the 
  cater 
  pillar 
  pest. 
  The 
  parasite 
  has 
  not 
  been 
  identified 
  yet 
  but 
  the 
  

   Imperial 
  Entomologist 
  has 
  kindly 
  undertaken 
  to 
  get 
  it 
  named 
  correctly. 
  

   A 
  short 
  summary 
  of 
  the 
  work 
  is 
  given 
  below 
  : 
  — 
  

  

  /. 
  Life 
  History 
  of 
  the 
  parasite. 
  

  

  Eggs. 
  The 
  eggs 
  are 
  cylindrical 
  and 
  elongated 
  with 
  the 
  two 
  ends 
  

   round 
  and 
  slightly 
  curved 
  in 
  the 
  middle 
  [Plate 
  XXVII 
  Fig. 
  2{^)]. 
  They 
  

   are 
  extremely 
  small, 
  not 
  visible 
  without 
  the 
  help 
  of 
  a 
  lens 
  or 
  microscope 
  

   and 
  are 
  laid 
  just 
  under 
  the 
  skin 
  of 
  very 
  young 
  host 
  caterpillars. 
  The 
  

   eggs 
  are 
  laid 
  on 
  any 
  part 
  of 
  the 
  host's 
  body 
  but 
  generally 
  on 
  the 
  dorsal 
  

   side 
  of 
  the 
  last 
  segment 
  of 
  the 
  thorax 
  or 
  first 
  few 
  segments 
  of 
  the 
  abdomen. 
  

   An 
  adult 
  female 
  suddenly 
  drops 
  on 
  the 
  back 
  of 
  the 
  host 
  caterpillar 
  and 
  

   immediately 
  cormnences 
  to 
  make 
  the 
  incision 
  with 
  the 
  ovipositor. 
  The 
  

   host 
  wriggles 
  with 
  pain 
  and 
  sometimes 
  turns 
  round 
  and 
  round 
  but 
  the 
  

   parasite 
  does 
  not 
  let 
  go 
  its 
  hold. 
  The 
  number 
  of 
  eggs 
  laid 
  at 
  a 
  time 
  by 
  

   one 
  female 
  parasite 
  has 
  not 
  been 
  determined 
  but 
  under 
  field 
  conditions 
  

   it 
  is 
  certain 
  that 
  one 
  female 
  lays 
  eggs 
  on 
  more 
  than 
  one 
  host. 
  The 
  egg 
  

   content 
  of 
  a 
  gravid 
  female 
  parasite 
  has, 
  on 
  dissection, 
  been 
  found 
  to 
  be 
  

   about 
  200 
  but 
  the 
  result 
  of 
  dissection 
  of 
  a 
  large 
  number 
  of 
  naturally 
  

   parasitized 
  caterpillars 
  collected 
  from 
  the 
  fields 
  shows 
  that 
  the 
  number 
  

   of 
  parasite 
  larvae 
  in 
  one 
  host 
  insect's 
  body 
  varies 
  from 
  20 
  to 
  60. 
  Under 
  

  

  ( 
  167 
  ) 
  

  

  