﻿The 
  British 
  Species 
  of 
  Andrena 
  and 
  Nomada. 
  229 
  

  

  when 
  the- 
  insects 
  come 
  into 
  contact. 
  The 
  burrows 
  of 
  

   colonies 
  of 
  Andrena 
  are 
  ravaged 
  by 
  Forfiada. 
  which 
  

   frequently 
  raise 
  their 
  young 
  in 
  them, 
  and 
  various 
  Carabid 
  

   beetles 
  and 
  the 
  Myriapod 
  Lithobivs 
  are 
  numerous 
  in 
  the 
  

   same 
  situation. 
  

  

  In 
  the 
  case 
  of 
  Nomada, 
  the 
  different 
  species 
  are 
  all 
  

   mentioned 
  hereafter 
  in 
  connection 
  with 
  those 
  of 
  Andrena, 
  

   which 
  they 
  parasitise. 
  It 
  is 
  possible 
  that 
  some 
  have 
  a 
  

   rather 
  wider 
  range 
  of 
  hosts 
  than 
  I 
  have 
  allowed. 
  Of 
  one 
  

   only, 
  N. 
  flavopicta 
  K. 
  {jacobaeae 
  Auct. 
  plur.), 
  the 
  host 
  

   appears 
  a 
  httle 
  doubtful. 
  Smith 
  records 
  it 
  as 
  having 
  

   once 
  been 
  seen 
  to 
  enter 
  the 
  burrow 
  of 
  the 
  second 
  brood 
  of 
  

   A. 
  flavipes 
  (fidvicrns), 
  and 
  this 
  may 
  be 
  its 
  host. 
  It 
  has, 
  

   however, 
  occurred 
  in 
  some 
  localities, 
  where 
  this 
  Andrena 
  

   either 
  does 
  not 
  occur 
  at 
  all 
  or, 
  at 
  any 
  rate, 
  has 
  been 
  over- 
  

   looked, 
  and 
  should 
  there 
  have 
  been 
  some 
  mistake 
  on 
  

   Smith's 
  part, 
  I 
  suggest 
  that 
  it 
  is 
  attached 
  to 
  members 
  of 
  

   the 
  group 
  of 
  A. 
  nigriceps, 
  one 
  or 
  other 
  of 
  which 
  I 
  have 
  

   always 
  found 
  present 
  in 
  its 
  localities. 
  Two 
  of 
  our 
  species 
  

   are 
  quite 
  peculiar 
  in 
  their 
  habits, 
  N. 
  sexfasciata 
  breeding 
  

   in 
  colonies 
  of 
  Eucera 
  longicornis 
  and 
  N. 
  furva 
  in 
  those 
  of 
  

   Halidus 
  nitidduscuhts. 
  The 
  latter 
  has 
  been 
  said 
  also 
  to 
  

   be 
  attached 
  to 
  H. 
  morio, 
  but 
  I 
  myself 
  have 
  never 
  found 
  

   this 
  to 
  be 
  the 
  case, 
  though 
  I 
  have 
  carefully 
  investigated 
  

   the 
  matter 
  in 
  such 
  distant 
  localities 
  as 
  Oxford, 
  Monmouth 
  

   and 
  Devon. 
  H. 
  morio 
  is 
  abundant 
  in 
  all 
  these 
  places, 
  but 
  

   the 
  Nomada 
  in 
  my 
  own 
  experience 
  either 
  attacked 
  pure 
  

   colonies 
  of 
  nitidiusculus, 
  or, 
  if 
  morio 
  occurred 
  in 
  the 
  same 
  

   bank, 
  was 
  only 
  obtained 
  from 
  the 
  burrows 
  of 
  the 
  former. 
  

   In 
  Devon 
  it 
  is 
  sometimes 
  found 
  in 
  mixed 
  colonies 
  of 
  

   H. 
  nitidiuscidus 
  and 
  minvtus,* 
  and 
  in 
  this 
  case, 
  owing 
  

   to 
  the 
  great 
  similarity 
  of 
  these 
  two 
  species, 
  I 
  could 
  not 
  be 
  

   sure 
  whether 
  one 
  or 
  both 
  were 
  attacked. 
  Smith 
  says 
  

   that 
  this 
  minute 
  species 
  was 
  obtained 
  from 
  the 
  cells 
  of 
  

   CoUetes 
  daviesana, 
  but 
  this, 
  of 
  course, 
  does 
  not 
  necessarily 
  

   mean 
  that 
  it 
  is 
  parasitic 
  on 
  that 
  bee. 
  Halicti, 
  like 
  other 
  

   bees, 
  sometimes 
  enter 
  burrows 
  made 
  by 
  other 
  species 
  

   and 
  form 
  their 
  nests 
  therein, 
  just 
  as 
  Andrenas 
  enter 
  rabbit, 
  

   rat, 
  and 
  mice 
  burrows. 
  Similarly, 
  Smith 
  records 
  finding 
  

   N. 
  marshamella 
  in 
  the 
  cell 
  of 
  Eucera, 
  this 
  no 
  doubt 
  having 
  

  

  * 
  Since 
  the 
  remarks 
  above 
  were 
  written 
  this 
  little 
  Nomada 
  has 
  

   been 
  obtained 
  before 
  the 
  time 
  of 
  emergence 
  from 
  burrows 
  of 
  H. 
  

   minufus, 
  and, 
  of 
  course, 
  it 
  may 
  well 
  be 
  parasitic 
  on 
  H. 
  morio, 
  but 
  

   positive 
  evidence 
  of 
  this 
  is 
  required. 
  

  

  