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  ANNUAL 
  REPORT 
  SMITHSONIAN 
  INSTITUTION, 
  1922. 
  

  

  In 
  compiling 
  the 
  catalogue 
  I 
  have 
  followed 
  the 
  classification 
  and 
  

   nomenclature 
  of 
  Charles 
  Robertson. 
  The 
  genera 
  are 
  therefore 
  used 
  

   in 
  the 
  Robertsonian 
  sense. 
  According 
  to 
  the 
  commoner 
  classification, 
  

   the 
  first 
  20 
  bees 
  on 
  the 
  list 
  would 
  be 
  placed 
  in 
  the 
  genus 
  Halictus. 
  

   These 
  20, 
  with 
  Dialonia 
  antennariae, 
  which 
  is 
  a 
  Sphecodes, 
  belong 
  

   to 
  the 
  family 
  Halictidae. 
  Calliopsis 
  andrenifor?nis, 
  however, 
  belongs 
  

   to 
  the 
  family 
  Panurgidae. 
  This 
  latter 
  species, 
  of 
  which 
  one 
  female 
  

   and 
  five 
  males 
  were 
  found 
  in 
  the 
  cells 
  of 
  the 
  wasp, 
  bears 
  a 
  super- 
  

   ficial 
  resemblance 
  to 
  Halictus 
  ligatus. 
  

  

  Shall 
  we 
  say 
  that 
  the 
  capture 
  of 
  these 
  six 
  Panurgid 
  bees 
  was 
  acci- 
  

   dental 
  ? 
  Shall 
  we 
  set 
  it 
  down 
  as 
  a 
  mistake 
  on 
  the 
  part 
  of 
  a 
  Philan- 
  

   thus 
  who 
  was 
  deceived 
  by 
  a 
  superficial 
  similarity 
  between 
  Calliopsis 
  

   and 
  Halictus? 
  That 
  we 
  should 
  have 
  to 
  do 
  if 
  we 
  were 
  certain 
  that 
  

   the 
  wasp 
  actually 
  selects 
  Halictidae. 
  To 
  make 
  such 
  an 
  exclusive 
  

   choice 
  the 
  wasp 
  must 
  possess 
  a 
  remarkable 
  instinct. 
  Size 
  affords 
  no 
  

   reliable 
  guide 
  when 
  the 
  bees 
  to 
  be 
  chosen 
  vary 
  from 
  3 
  millimeters 
  to 
  

   three 
  times 
  that 
  in 
  length. 
  Color 
  is 
  still 
  more 
  confusing. 
  The 
  prey 
  

   of 
  Philanthus 
  includes 
  bees 
  clad 
  in 
  brown 
  or 
  dull 
  russet; 
  others 
  ar« 
  

   girdled 
  with 
  yellow, 
  banded 
  with 
  white, 
  adorned 
  with 
  hoary 
  wool; 
  

   others 
  are 
  bright 
  metallic 
  green, 
  red, 
  blue, 
  ebony 
  black, 
  or 
  golden 
  

   green 
  ; 
  and 
  underneath 
  this 
  variety 
  of 
  garb 
  and 
  livery 
  the 
  wasp 
  must 
  

   recognize 
  the 
  invariable 
  Halictus. 
  Endowed 
  with 
  such 
  a 
  talent, 
  the 
  

   Philanthus 
  would 
  be 
  a 
  rival 
  to 
  expert 
  melittologists 
  ; 
  she 
  would 
  have 
  

   more 
  skill 
  than 
  our 
  professional 
  classifiers 
  — 
  a 
  conclusion 
  that 
  Henri 
  

   Fabre 
  would 
  most 
  heartily 
  indorse. 
  

  

  But 
  the 
  problem 
  permits 
  of 
  another 
  solution. 
  It 
  can 
  be 
  solved 
  by 
  

   saying 
  that 
  Philanthus 
  takes 
  any 
  bees 
  of 
  proper 
  size 
  that 
  visit 
  the 
  

   flowers 
  during 
  her 
  hunting 
  season. 
  Halictid 
  bees 
  are 
  captured 
  in 
  

   such 
  abundance 
  not 
  because 
  the 
  huntress 
  is 
  a 
  specialist 
  on 
  Halictidae 
  

   but 
  because 
  they 
  form 
  the 
  almost 
  exclusive 
  population 
  of 
  the 
  summer 
  

   field 
  flowers. 
  This 
  solution 
  is 
  plausible 
  enough, 
  but 
  requires 
  for 
  

   proof 
  more 
  study 
  and 
  experiment 
  than 
  I 
  have 
  been 
  able 
  to 
  give 
  the 
  

   question. 
  

  

  A 
  third 
  suggestion 
  is 
  possible. 
  In 
  our 
  neighborhood 
  I 
  have 
  seen 
  

   Philanthus 
  gibbosus 
  hunting 
  or 
  feeding 
  on 
  the 
  flowers 
  of 
  Wild 
  Car- 
  

   rot 
  (Daucus 
  cavota), 
  Yarrow 
  (Achillea 
  millefolium), 
  Daisy 
  Flea- 
  

   bane 
  (Erigeron 
  ramosus), 
  Lady's 
  Thumb 
  (Polygonum 
  persicaria), 
  

   and 
  the 
  cultivated 
  Gaillardia 
  (Gaillardia 
  grandiflora) 
  , 
  and 
  Chinese 
  

   Woolflower 
  (Celosia 
  plumosa) 
  in 
  the 
  garden. 
  These 
  are 
  all 
  flowers 
  

   whose 
  surgary 
  corollas 
  are 
  patronized 
  largely 
  by 
  Halictidae. 
  It 
  

   might 
  accordingly 
  be 
  suggested 
  that 
  the 
  preponderance 
  of 
  Halictid 
  

   prey 
  is 
  an 
  accident 
  resulting 
  from 
  the 
  partiality 
  of 
  Philanthus 
  for 
  

   flowers 
  which 
  Halictidae 
  prefer. 
  But 
  this 
  answer 
  of 
  itself 
  scarcely 
  

   solves 
  our 
  difficulty. 
  It 
  merely 
  leads 
  to 
  another 
  question 
  : 
  Does 
  Phil- 
  

  

  