﻿250 
  D. 
  d'emmerez 
  de 
  charmoy. 
  

  

  the 
  partiality 
  exhibited 
  by 
  these 
  insects 
  for 
  certain 
  flowers, 
  though 
  not 
  exclusive, 
  

   is 
  none 
  the 
  less 
  real 
  ; 
  and 
  that 
  this 
  partiality 
  is 
  extended 
  in 
  various 
  degrees 
  to 
  a 
  

   certain 
  number 
  of 
  flowers. 
  

  

  For 
  example, 
  the 
  gathering 
  observed 
  on 
  the 
  paka 
  field 
  indicated 
  that 
  the 
  flowers 
  

   of 
  this 
  plant 
  exerted 
  on 
  these 
  insects 
  a 
  peculiar 
  attraction 
  that 
  induced 
  them 
  to 
  

   abandon 
  other 
  flowers 
  in 
  the 
  region 
  to 
  group 
  themselves 
  at 
  the 
  point 
  where 
  these 
  

   plants 
  occurred. 
  Their 
  sudden 
  appearance 
  in 
  numbers 
  on 
  two 
  successive 
  days, 
  

   together 
  with 
  the 
  subsequent 
  absence 
  of 
  other 
  Scoliids 
  after 
  the 
  existing 
  lot 
  had 
  been 
  

   captured, 
  tend 
  to 
  prove 
  that 
  the 
  insects, 
  whether 
  they 
  had 
  reached 
  this 
  field 
  directly 
  

   or 
  by 
  stages 
  from 
  long 
  distances, 
  had 
  established 
  their 
  quarters 
  there 
  for 
  some 
  time, 
  

   owing 
  to 
  the 
  existence 
  of 
  their 
  favourite 
  pasture. 
  This 
  case 
  bears 
  a 
  complete 
  analogy 
  

   to 
  that 
  of 
  Ste 
  Marie, 
  though 
  in 
  Ste 
  Marie 
  the 
  scarcity 
  of 
  flowers 
  on 
  the 
  shrub 
  with 
  

   red 
  berries 
  had 
  already 
  caused 
  the 
  dispersion 
  of 
  a 
  good 
  number 
  of 
  insects. 
  This 
  

   dispersion 
  would 
  have 
  occurred 
  subsequently 
  in 
  the 
  paka 
  field, 
  as 
  there 
  was 
  no 
  other 
  

   plant 
  on 
  which 
  the 
  Scoliids 
  could 
  feed. 
  

  

  At 
  the 
  time 
  I 
  visited 
  Anamalotreta 
  the 
  scarcity 
  of 
  paka 
  flowers 
  had 
  already 
  

   made 
  itself 
  felt, 
  and 
  would 
  probably 
  have 
  led 
  to 
  the 
  dispersal 
  of 
  the 
  wasps 
  had 
  not 
  

   the 
  sweet 
  potatoes 
  been 
  in 
  bloom, 
  thereby 
  retarding 
  their 
  exodus. 
  The 
  blossoms 
  of 
  

   mandarin 
  orange 
  trees 
  further 
  intervened, 
  and 
  thus 
  extended 
  the 
  duration 
  of 
  the 
  

   gathering 
  until 
  the 
  time 
  of 
  our 
  departure 
  from 
  Tamatave, 
  on 
  19th 
  August. 
  The 
  

   fact 
  that 
  these 
  insects 
  abandoned 
  the 
  sweet 
  potato 
  flowers 
  on 
  the 
  very 
  day 
  on 
  which 
  

   the 
  mandarin 
  flowers 
  opened 
  brings 
  out 
  clearly 
  their 
  partiality 
  for 
  certain 
  flowers, 
  

   and 
  explains 
  at 
  the 
  same 
  time 
  why 
  we 
  hardly 
  ever 
  came 
  across 
  these 
  large 
  Scoliids 
  

   on 
  convolvulus 
  and 
  various 
  other 
  flowers. 
  This 
  peculiarity, 
  to 
  which 
  we 
  owe 
  the 
  

   success 
  of 
  our 
  enterprise, 
  has 
  a 
  far 
  greater 
  significance 
  than 
  one 
  would 
  assign 
  to 
  it 
  at 
  

   first 
  sight. 
  

  

  In 
  a 
  country 
  like 
  Mauritius, 
  where 
  Oryctes 
  are 
  found 
  everywhere, 
  the 
  important 
  

   point 
  is 
  not 
  a 
  reduction 
  of 
  the 
  total 
  number 
  of 
  these 
  insects, 
  but 
  a 
  reduction 
  induced 
  

   at 
  particular 
  points, 
  i.e., 
  on 
  cultivated 
  lands, 
  where 
  the 
  intensity 
  of 
  the 
  infestation 
  

   is 
  responsible 
  for 
  considerable 
  damage. 
  To 
  attain 
  this 
  end 
  it 
  would 
  suffice 
  to 
  group 
  

   at 
  particular 
  spots 
  where 
  Oryctes 
  are 
  numerous 
  and 
  harmful 
  the 
  greatest 
  possible 
  

   number 
  of 
  Scoliids. 
  This 
  gathering 
  could 
  easily 
  be 
  induced 
  by 
  establishing 
  at 
  these 
  

   points 
  some 
  description 
  of 
  artificial 
  pastures 
  which 
  would 
  confine 
  the 
  wasps 
  thereto 
  

   as 
  long 
  as 
  required. 
  

  

  These 
  observations 
  are 
  equally 
  true 
  for 
  other 
  species 
  than 
  S. 
  oryctophaga 
  ; 
  for 
  

   example, 
  S. 
  iridicolor, 
  Elis 
  pfeifferae, 
  and 
  E. 
  thoracica, 
  the 
  last-named 
  species 
  having 
  

   a 
  preference 
  for 
  " 
  queue 
  de 
  rat 
  " 
  (Stachytarpheta 
  indica). 
  In 
  Mauritius 
  Cordia 
  

   interrupta 
  attracts 
  Tiphia 
  parallela 
  in 
  a 
  somewhat 
  similar 
  fashion 
  ; 
  while 
  Elis 
  rufa 
  

   also, 
  feeds 
  on 
  its 
  flowers. 
  

  

  It 
  follows 
  from 
  the 
  foregoing 
  remarks 
  that 
  it 
  is 
  useless 
  to 
  endeavour 
  to 
  acclimatise 
  

   Scoliids 
  in 
  a 
  new 
  environment 
  unless 
  their 
  habits 
  are 
  known 
  and 
  the 
  conditions 
  

   favourable 
  to 
  their 
  acclimatisation 
  are 
  fulfilled, 
  such 
  as 
  the 
  supplying 
  of 
  the 
  proper 
  

   flowers 
  to 
  serve 
  as 
  food 
  for 
  the 
  adults. 
  In 
  countries 
  such 
  as 
  Queensland, 
  Porto 
  Rico, 
  

   etc., 
  where 
  white 
  grubs 
  are 
  responsible 
  for 
  considerable 
  damage 
  and 
  where 
  their 
  

   natural 
  enemies 
  already 
  exist, 
  advantage 
  might 
  be 
  taken 
  of 
  the 
  feeding 
  habits 
  of 
  the 
  

   adult 
  parasites 
  to 
  increase 
  the 
  efficiency 
  of 
  their 
  control 
  by 
  providing 
  suitable 
  pasturage 
  

   on 
  the 
  lines 
  indicated. 
  

  

  Conditions 
  under 
  which 
  the 
  Scoliids 
  were 
  conveyed 
  to 
  Mauritius. 
  

  

  Scolia 
  oryctophaga 
  is 
  an 
  extremely 
  hardy 
  species 
  and 
  is 
  easily 
  reared 
  in 
  captivity. 
  

   The 
  cages 
  used 
  for 
  conveying 
  these 
  insects 
  from 
  Madagascar 
  to 
  Mauritius 
  were 
  large 
  

   Wardian 
  cases 
  in 
  which 
  Tiphia 
  parallela 
  had 
  been 
  imported 
  from 
  Barbados. 
  On 
  

   account 
  of 
  their 
  size 
  and 
  weight 
  these 
  cases 
  could 
  not 
  easily 
  be 
  carried 
  about 
  and 
  

   had 
  to 
  be 
  left 
  behind 
  whenever 
  we 
  went 
  into 
  the 
  bush. 
  In 
  practice, 
  the 
  insects 
  as 
  

  

  