﻿INTRODUCING 
  SCOLIID 
  WASPS 
  FROM 
  MADAGASCAR 
  TO 
  MAURITIUS. 
  249 
  

  

  On 
  the 
  5 
  th 
  I 
  proceeded 
  to 
  Anamalotreta. 
  This 
  village 
  occupies 
  the 
  end 
  portion 
  

   of 
  a 
  sort 
  of 
  peninsula 
  formed 
  by 
  the 
  junction 
  of 
  two 
  rivers 
  that 
  isolate 
  it 
  on 
  the 
  east 
  

   from 
  the 
  plains 
  that 
  extend 
  in 
  the 
  direction 
  of 
  the 
  sea. 
  On 
  the 
  left 
  of 
  the 
  road, 
  

   where 
  the 
  peninsula 
  widens, 
  begins 
  the 
  region 
  of 
  hillocks 
  ; 
  2 
  km. 
  further 
  west 
  the 
  

   Ivoloina 
  directs 
  its 
  course 
  eastwards 
  towards 
  the 
  sea. 
  

  

  The 
  native 
  huts 
  are 
  here 
  surrounded 
  by 
  citrus 
  fruits 
  and 
  coconut 
  palms 
  ; 
  behind 
  

   them 
  on 
  the 
  plain 
  were 
  a 
  few 
  sweet 
  potato 
  fields 
  in 
  full 
  bloom. 
  Paka 
  plants 
  were 
  

   numerous, 
  but 
  scattered, 
  and 
  had 
  almost 
  entirely 
  lost 
  their 
  leaves. 
  A 
  small 
  field 
  

   of 
  sweet 
  potatoes 
  in 
  full 
  bloom 
  was 
  observed, 
  over 
  which 
  large 
  numbers 
  of 
  male 
  

   5. 
  oryctophaga 
  were 
  flying 
  close 
  to 
  the 
  ground, 
  sometimes 
  alighting 
  on 
  heaps 
  of 
  dried 
  

   leaves 
  and 
  weeds, 
  in 
  the 
  midst 
  of 
  which 
  they 
  disappeared, 
  to 
  emerge 
  soon 
  after. 
  

   After 
  two 
  hours' 
  waiting 
  I 
  captured 
  five 
  males, 
  having 
  failed 
  to 
  see 
  a 
  single 
  female, 
  

   and 
  on 
  retiring 
  to 
  the 
  village 
  several 
  other 
  small 
  sweet 
  potato 
  fields 
  were 
  seen, 
  in 
  

   one 
  of 
  which 
  I 
  captured 
  10 
  females 
  on 
  the 
  flowers 
  in 
  less 
  than 
  an 
  hour. 
  

  

  Later 
  I 
  visited 
  other 
  fields 
  withoiit 
  coming 
  across 
  any 
  more 
  Scoliids. 
  On 
  

   returning 
  I 
  noticed 
  a 
  great 
  number 
  of 
  the 
  wasps 
  at 
  the 
  top 
  of 
  a 
  mandarin 
  orange 
  

   tree, 
  of 
  which 
  the 
  flowers 
  had 
  hardly 
  commenced 
  opening 
  out. 
  To 
  capture 
  them 
  

   I 
  had 
  to 
  climb 
  up 
  to 
  the 
  top 
  of 
  the 
  tree, 
  and 
  in 
  two 
  hours 
  had 
  caught 
  17 
  female 
  

   S. 
  oryctophaga 
  and 
  3 
  males, 
  bringing 
  up 
  to 
  48 
  the 
  number 
  of 
  females 
  captured 
  in 
  

   four 
  days. 
  

  

  On 
  8th 
  August 
  I 
  forwarded 
  to 
  Mauritius 
  140 
  Scoliids, 
  including 
  97 
  female 
  

   S. 
  oryctophaga. 
  From 
  the 
  9th 
  to 
  the 
  19th, 
  the 
  date 
  on 
  which 
  I 
  left 
  Madagascar 
  for 
  

   Mauritius, 
  I 
  captured 
  on 
  a 
  few 
  mandarin 
  orange 
  trees 
  at 
  Anamalotreta 
  767 
  Scoliids, 
  

   including 
  434 
  female 
  S. 
  oryctophaga. 
  

  

  A 
  Method 
  of 
  concentrating 
  the 
  Parasites 
  in 
  a 
  given 
  Area. 
  

  

  From 
  14th 
  June 
  to 
  2nd 
  August 
  (54 
  days) 
  our 
  total 
  captures 
  in 
  Ste 
  Marie 
  and 
  

   Tanamakoa, 
  for 
  a 
  journey 
  of 
  more 
  than 
  100 
  km., 
  amounted 
  only 
  to 
  12 
  female 
  

   5. 
  oryctophaga 
  and 
  E. 
  romandi 
  ; 
  while 
  from 
  2nd 
  to 
  19th 
  August 
  (17 
  days), 
  and 
  within 
  

   a 
  perimeter 
  of 
  100 
  metres 
  only, 
  15 
  female 
  S. 
  oryctophaga, 
  128 
  males, 
  and 
  20 
  E. 
  romandi 
  

   (163 
  insects 
  in 
  all) 
  were 
  secured, 
  a 
  number 
  which 
  may 
  be 
  regarded 
  as 
  very 
  satisfactory, 
  

   considering 
  the 
  large 
  size 
  of 
  the 
  insects. 
  

  

  So 
  great 
  a 
  difference 
  in 
  the 
  number 
  of 
  insects 
  captured 
  in 
  these 
  two 
  different 
  

   periods 
  can 
  only 
  be 
  accounted 
  for 
  by 
  appealing 
  to 
  particular 
  conditions, 
  for 
  it 
  would 
  

   be 
  unreasonable 
  to 
  suppose 
  that 
  all 
  these 
  insects 
  were 
  originally 
  present 
  in 
  the 
  place 
  

   where 
  they 
  had 
  been 
  captured, 
  inasmuch 
  as 
  the 
  conditions 
  favouring 
  the 
  development 
  

   of 
  Oryctes 
  and 
  other 
  Lamellicorn 
  beetles 
  did 
  not 
  differ 
  at 
  all 
  there 
  from 
  those 
  that 
  

   obtained 
  elsewhere. 
  If 
  we 
  examine 
  the 
  various 
  hypotheses 
  previously 
  put 
  forward 
  

   we 
  can 
  see 
  that 
  the 
  effect 
  of 
  season 
  is 
  insufficient 
  to 
  account 
  for 
  so 
  great 
  a 
  gathering 
  

   of 
  insects 
  at 
  one 
  particular 
  spot. 
  That 
  these 
  insects 
  should 
  be 
  more 
  numerous 
  at 
  a 
  

   certain 
  time 
  of 
  the 
  year 
  is 
  but 
  natural. 
  If, 
  however, 
  this 
  was 
  the 
  only 
  controlling 
  

   factor 
  they 
  would 
  be 
  distributed 
  more 
  or 
  less 
  uniformly, 
  thus 
  frequently 
  bearing 
  

   a 
  constant 
  ratio 
  to 
  the 
  number 
  of 
  Oryctes. 
  It 
  has, 
  however, 
  already 
  been 
  pointed 
  out 
  

   that 
  the 
  dissemination 
  and 
  relative 
  scarcity 
  of 
  Oryctes 
  larvae 
  precluded 
  the 
  possibility 
  

   of 
  securing 
  the 
  number 
  of 
  Scoliids 
  needed 
  in 
  the 
  cocoon 
  stage. 
  

  

  The 
  hypothesis 
  that 
  the 
  gathering 
  of 
  these 
  insects 
  is 
  attributable 
  to 
  their 
  sedentary 
  

   habits 
  does 
  not 
  hold 
  good 
  in 
  view 
  of 
  the 
  facts 
  mentioned 
  above, 
  and 
  the 
  third 
  

   hypothesis 
  remains, 
  viz., 
  that 
  the 
  insects 
  possess 
  an 
  extraordinary 
  capacity 
  for 
  flight, 
  

   which 
  enables 
  them 
  to 
  seek 
  the 
  kind 
  of 
  food 
  that 
  they 
  prefer 
  over 
  considerable 
  

   distances. 
  The 
  facts 
  observed 
  at 
  Ste 
  Marie, 
  in 
  the 
  paka 
  field, 
  and 
  at 
  Anamalotreta 
  

   village 
  support 
  this 
  view. 
  The 
  absence 
  of 
  Scoliids 
  on 
  flowers 
  of 
  Convolvulaceae 
  at 
  

   Ste 
  Marie, 
  as 
  well 
  as 
  on 
  the 
  Ivondro 
  and 
  on 
  the 
  plains 
  of 
  Tamatave, 
  and 
  the 
  presence 
  

   of 
  these 
  insects 
  in 
  considerable 
  numbers 
  on 
  these 
  same 
  flowers 
  at 
  Anamalotreta 
  

   would 
  appear 
  to 
  conflict 
  with 
  this 
  view 
  at 
  first. 
  But 
  a 
  closer 
  examination 
  shows 
  that 
  

  

  