﻿220 
  Mr. 
  R. 
  C. 
  L. 
  Perkins 
  on 
  

  

  Hants, 
  there 
  was 
  a 
  colony 
  " 
  so 
  numerous 
  that 
  their 
  flight 
  

   as 
  they 
  skim 
  over 
  the 
  surface 
  of 
  the 
  gromid, 
  produces 
  a 
  

   loud 
  humming 
  noise." 
  I 
  have 
  noticed 
  similar 
  colonies 
  

   of 
  this 
  species 
  myself, 
  and 
  have 
  recorded 
  the 
  same 
  of 
  A. 
  

   wilkella. 
  Other 
  species 
  that 
  do 
  not 
  form 
  those 
  huge 
  dense 
  

   colonies 
  are 
  sometimes 
  equally 
  successful 
  in 
  the 
  production 
  

   of 
  individuals, 
  and 
  I 
  suppose 
  every 
  one 
  must 
  have 
  noted 
  

   the 
  incalculable 
  numbers 
  of 
  A. 
  albicans 
  that 
  may 
  be 
  seen 
  

   flying 
  along 
  a 
  single 
  hedgerow, 
  or 
  of 
  mixed 
  common 
  species 
  

   flying 
  round 
  some 
  attractive 
  flowering 
  tree 
  or 
  bush. 
  At 
  

   times 
  local 
  or 
  even 
  rare 
  species 
  may 
  be 
  observed 
  in 
  numbers 
  

   not 
  at 
  all 
  inferior 
  to 
  those 
  of 
  the 
  commonest. 
  Indeed, 
  

   many 
  of 
  the 
  most 
  local 
  species, 
  where 
  they 
  do 
  occur, 
  are 
  

   amongst 
  the 
  most 
  plentiful. 
  In 
  Devonshire 
  we 
  have 
  seen 
  

   at 
  times 
  the 
  males 
  of 
  A. 
  synadelpha 
  {ambigua), 
  fucata, 
  

   fulvago, 
  bimaculata 
  and 
  others 
  so 
  numerous 
  on 
  the 
  wing 
  

   that 
  a 
  number 
  could 
  be 
  taken 
  at 
  a 
  single 
  stroke 
  of 
  the 
  net. 
  

   One 
  most 
  noticeable 
  feature 
  about 
  the 
  species 
  of 
  Andrena 
  

   is 
  the 
  frequent 
  apparent 
  disparity 
  of 
  the 
  sexes 
  in 
  the 
  number 
  

   of 
  individuals 
  observed, 
  when 
  both 
  (^ 
  and 
  $ 
  are 
  fully 
  out. 
  

   Thus 
  in 
  the 
  case 
  of 
  A. 
  synadelpha 
  above 
  mentioned, 
  if 
  one. 
  

   stands 
  for 
  an 
  hour 
  or 
  two 
  by 
  a 
  hedgerow 
  that 
  I 
  have 
  in 
  mind, 
  

   up 
  and 
  down 
  which 
  the 
  males 
  are 
  coursing 
  in 
  great 
  numbers, 
  

   it 
  is 
  most 
  probable 
  that 
  not 
  more 
  than 
  one 
  or 
  two 
  females 
  

   will 
  be 
  seen. 
  These 
  burrow 
  in 
  a 
  scattered 
  fashion 
  over 
  the 
  

   adjoining 
  heath, 
  and 
  do 
  not 
  flock, 
  like 
  the 
  males, 
  to 
  the 
  

   hedge 
  that 
  borders 
  it, 
  so 
  that, 
  unless 
  one 
  happens 
  to 
  be 
  

   found 
  sunning 
  itself 
  on 
  a 
  leaf 
  or 
  entering 
  a 
  burrow, 
  it 
  is 
  

   quite 
  possible 
  that 
  not 
  even 
  a 
  single 
  example 
  of 
  this 
  sex 
  

   will 
  be 
  met 
  with. 
  Nor 
  have 
  I 
  ever 
  found 
  them 
  on 
  flowers 
  

   in 
  the 
  immediate 
  vicinity, 
  and 
  they 
  must 
  go 
  elsewhere 
  to 
  

   find 
  these. 
  Mr. 
  Morice 
  once 
  lent 
  me 
  a 
  long 
  series 
  of 
  beauti- 
  

   fully 
  fresh 
  females 
  of 
  this 
  species 
  which 
  he 
  found 
  all 
  together 
  

   (and 
  many 
  males 
  in 
  their 
  company) 
  on 
  the 
  flowers 
  of 
  

   Erysimum 
  alliaria, 
  but 
  this 
  plant 
  does 
  not 
  grow 
  in 
  the 
  

   locaUty 
  where 
  I 
  fuid 
  the 
  males 
  so 
  plentifully. 
  If, 
  when 
  a 
  

   species 
  first 
  appears, 
  the 
  weather 
  continues 
  fine 
  and 
  hot, 
  

   the 
  males 
  generally 
  last 
  for 
  a 
  very 
  short 
  time. 
  This 
  is 
  

   especially 
  the 
  case 
  with 
  many 
  of 
  the 
  less 
  common 
  species, 
  

   and 
  it 
  is 
  very 
  annoying 
  to 
  find 
  a 
  plentiful 
  supply 
  of 
  females 
  

   of 
  a 
  desirable 
  species, 
  either 
  on 
  flowers 
  or 
  at 
  their 
  burrows, 
  

   and 
  not 
  to 
  be 
  able 
  to 
  secure 
  a 
  single 
  specimen, 
  or 
  only 
  a 
  few 
  

   old 
  and 
  worn 
  specimens, 
  of 
  the 
  other 
  sex. 
  The 
  males 
  in- 
  

   variably 
  appear 
  before 
  the 
  females, 
  either 
  by 
  a 
  day 
  or 
  two 
  or 
  

  

  