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  trachea. 
  The 
  chitin-layer 
  is 
  continued 
  by 
  a 
  firm 
  layer 
  of 
  

   densly 
  compressed 
  and 
  destroyed 
  fat-cells. 
  The 
  larvæ 
  

   hibernaie 
  in 
  the 
  second 
  stage, 
  develop 
  in 
  spring 
  to 
  the 
  

   third 
  stage, 
  pupate 
  in 
  the 
  abdoraen 
  of 
  the 
  beetle, 
  and 
  the 
  

   imagos 
  leave 
  this 
  through 
  a 
  hole 
  in 
  its 
  posterior 
  end. 
  In 
  

   each 
  beetle 
  up 
  to 
  7 
  parasites 
  may 
  be 
  found. 
  

  

  Ocyplera 
  brassicaria 
  F. 
  is 
  parasitic 
  on 
  Dolycoris 
  baccarum 
  

   F. 
  Its 
  relation 
  to 
  the 
  hemiptere 
  agrees 
  with 
  what 
  has 
  

   been 
  described 
  with 
  regard 
  to 
  the 
  Viviana, 
  with 
  the 
  excep- 
  

   tion 
  that 
  there 
  is 
  no 
  layer 
  of 
  destroyed 
  fat-cells 
  round 
  the 
  

   larvæ 
  (Fig. 
  10). 
  The 
  parasite 
  hibernates 
  in 
  the 
  second 
  

   stage; 
  the 
  boring 
  out 
  which 
  takes 
  place 
  in 
  June 
  and 
  July 
  

   does 
  not 
  kill 
  the 
  host. 
  The 
  pupation 
  follows 
  in 
  the 
  ground. 
  

   Only 
  one 
  parasite 
  is 
  present 
  in 
  each 
  hemiptere. 
  

  

  Explanation 
  of 
  the 
  Piates. 
  

  

  PL 
  1. 
  

  

  Ptychomyia 
  selecta 
  Meig. 
  

  

  Fig. 
  1. 
  Transverse 
  section 
  of 
  a 
  larva 
  of 
  Hyponomeuta 
  

   emmjmella 
  soraetime 
  after 
  the 
  boring 
  in 
  of 
  a 
  

   Ptychomyia 
  selecta-\?iXV2i', 
  the 
  parasite 
  is 
  not 
  shown. 
  

   41/1. 
  æ. 
  eggshell; 
  ih. 
  the 
  hole 
  through 
  which 
  the 
  

   parasite 
  has 
  penetrated 
  into 
  the 
  host; 
  k. 
  chitinous 
  

   invagination 
  of 
  the 
  host's 
  cuticula 
  which 
  forms 
  the 
  

   funnel; 
  ki. 
  lighter 
  chitin 
  on 
  the 
  outside 
  of 
  the 
  

   funnel; 
  1. 
  leucocytes; 
  s. 
  the 
  sac 
  that 
  surrounds 
  

   the 
  parasite 
  and 
  which 
  is 
  formed 
  of 
  emptied 
  fat- 
  

   cells; 
  t. 
  the 
  alimentary 
  canal 
  of 
  the 
  host; 
  uh. 
  the 
  

   hole 
  through 
  which 
  the 
  parasite 
  leaves 
  the 
  egg; 
  ep. 
  

   the 
  host's 
  hypoderma; 
  oc. 
  the 
  cuticula 
  of 
  the 
  host. 
  

  

  Fig. 
  2. 
  The 
  side 
  of 
  a 
  hole 
  through 
  which 
  the 
  parasite 
  has 
  

   penetrated 
  into 
  the 
  host, 
  shortly 
  after 
  the 
  penetration. 
  

   The 
  letters 
  as 
  in 
  fig. 
  1. 
  ^"/i. 
  

  

  