﻿120 
  

  

  one 
  parasite 
  in 
  each 
  host 
  larva 
  attains 
  to 
  full 
  development. 
  

   The 
  larva 
  of 
  Steiniella 
  callida 
  Meig. 
  develops 
  quite 
  in 
  the 
  

   same 
  way 
  in 
  the 
  larva 
  of 
  Lina 
  populi. 
  The 
  parasite 
  gene- 
  

   rally 
  bores 
  its 
  way 
  out 
  of 
  the 
  host 
  larva, 
  but 
  sometiraes 
  

   the 
  latter 
  pupates 
  before 
  the 
  parasite 
  is 
  fullgrown. 
  Carcetia 
  

   gnava 
  B. 
  & 
  B. 
  deposits 
  its 
  eggs 
  in 
  July 
  and 
  August 
  on 
  

   fullgrown 
  larvæ 
  of 
  Malacosoma 
  castrensis 
  L. 
  The 
  host 
  larva 
  

   always 
  pupates 
  before 
  the 
  parasite 
  is 
  fullgrown. 
  The 
  parasites 
  

   pupate 
  in 
  the 
  pupa 
  of 
  the 
  host 
  and 
  hibernate 
  in 
  this. 
  From 
  

   2 
  to 
  5 
  parasites 
  develop 
  in 
  each 
  host. 
  Tachina 
  larvarum 
  L. 
  

   has 
  several 
  generations 
  during 
  the 
  year. 
  A 
  summer 
  gene- 
  

   ration 
  deposited 
  its 
  larvæ 
  in 
  July 
  on 
  fullgrown 
  larvæ 
  of 
  

   Malacosoma 
  castrensis 
  L. 
  The 
  host 
  larva 
  pupated 
  with 
  the 
  

   parasites 
  in 
  its 
  body 
  and 
  the 
  parasite 
  larvæ 
  pupated 
  in 
  the 
  

   lepidopterous 
  pupa. 
  The 
  developed 
  flies 
  appeared 
  in 
  August. 
  

   An 
  autumn 
  generation 
  was 
  parasitic 
  in 
  both 
  older 
  and 
  

   younger 
  larvæ 
  of 
  Spilosoma 
  lubricipeda 
  L. 
  The 
  parasite 
  larvæ 
  

   all 
  went 
  out 
  of 
  the 
  host 
  larvæ 
  and 
  pupated 
  in 
  the 
  ground; 
  

   most 
  of 
  the 
  pupæ 
  hibernated, 
  but 
  from 
  a 
  few 
  the 
  fly 
  appea- 
  

   red 
  in 
  October. 
  I 
  have 
  found 
  2 
  to 
  7 
  larvæ 
  in 
  each 
  host 
  

   larva; 
  when 
  a 
  larger 
  number 
  of 
  larvæ 
  occur 
  some 
  of 
  the 
  

   imagos 
  are 
  generally 
  dwarf-specimens, 
  and 
  the 
  pupæ 
  of 
  

   these 
  differ 
  from 
  the 
  pupæ 
  of 
  the 
  normal 
  specimens 
  in 
  several 
  

   respects 
  (different 
  colour, 
  shape 
  and 
  sculpture). 
  

  

  The 
  larvæ 
  of 
  this 
  species 
  and 
  that 
  of 
  the 
  foregoing 
  

   may 
  occur 
  together 
  in 
  one 
  Malacosoma-\diX\2i, 
  and 
  they 
  may 
  

   develop 
  side 
  by 
  side 
  without 
  difficulty. 
  

  

  Of 
  flies 
  parasitic 
  on 
  imagines 
  I 
  have 
  examined 
  two 
  

   species. 
  Viviana 
  cinerea 
  Zett. 
  occurs 
  in 
  species 
  of 
  Carabus 
  

   and 
  in 
  Procrustes 
  coriaceus. 
  The 
  larvæ 
  are 
  attached 
  to 
  a 
  

   trachea 
  by 
  a 
  contraction 
  of 
  its 
  chitin, 
  which 
  part 
  forms 
  a 
  

   funnel, 
  enclosing 
  the 
  posterior 
  end 
  of 
  the 
  parasite 
  larva 
  (Fig. 
  

   8,9 
  k). 
  On 
  the 
  outside 
  of 
  the 
  chitinous 
  funnel 
  there 
  is 
  a 
  

   cell-coating 
  which 
  has 
  grown 
  out 
  from 
  the 
  epithelium 
  of 
  the 
  

  

  