﻿104 
  F. 
  W. 
  DRY. 
  

  

  (10-11 
  mm.) 
  were 
  brought 
  in 
  and 
  fed, 
  and 
  none 
  of 
  them 
  moulted 
  except 
  in 
  the 
  act 
  of 
  

   pupating. 
  It 
  would 
  therefore 
  seem 
  that 
  three 
  is 
  the 
  number 
  of 
  moults, 
  particulars 
  

   about 
  these 
  being 
  as 
  follows 
  : 
  — 
  

  

  Length 
  of 
  larva, 
  Breadth 
  of 
  head 
  No. 
  of 
  days 
  after 
  

  

  about 
  capsule 
  hatching, 
  about 
  

   On 
  hatching 
  .. 
  6 
  mm. 
  2\ 
  mm. 
  

  

  Moult 
  i 
  .. 
  .. 
  12 
  mm. 
  2|- 
  mm. 
  4 
  days. 
  

  

  Moult 
  ii 
  .. 
  .. 
  21mm. 
  5-6 
  mm. 
  22 
  days. 
  

  

  Moult 
  iii 
  .. 
  .. 
  43 
  mm. 
  10-11 
  mm. 
  48 
  days. 
  

  

  Approximate 
  data 
  for 
  the 
  length 
  of 
  the 
  larval 
  period 
  were, 
  however, 
  obtained 
  

   in 
  the 
  following 
  ways. 
  Grubs 
  which 
  had 
  just 
  hatched 
  were 
  placed 
  in 
  coconut 
  logs 
  

   beginning 
  to 
  rot, 
  these 
  logs 
  having 
  been 
  boiled 
  in 
  a 
  way 
  found 
  sufficient 
  to 
  kill 
  all 
  

   the 
  contained 
  beetle 
  eggs 
  and 
  grubs. 
  About 
  half 
  a 
  dozen 
  freshly 
  hatched 
  grubs 
  

   were 
  placed 
  in 
  each, 
  all 
  on 
  the 
  same 
  day. 
  They 
  were 
  kept 
  in 
  4-gallon 
  tins 
  or 
  in 
  barrels 
  

   and 
  left 
  undisturbed 
  for 
  some 
  period 
  such 
  as 
  60 
  or 
  80 
  days. 
  They 
  were 
  then 
  split 
  

   open 
  and 
  after 
  being 
  examined 
  were 
  tied 
  up 
  with 
  any 
  grubs 
  they 
  were 
  found 
  to 
  

   contain 
  still 
  inside, 
  or 
  the 
  grubs 
  were 
  placed 
  inside 
  other 
  rotten 
  logs, 
  or 
  kept 
  in 
  fibrous 
  

   material 
  from 
  a 
  decaying 
  log 
  in 
  the 
  tins. 
  The 
  mortality 
  was 
  again 
  high, 
  nine-tenths 
  

   dying 
  ; 
  but 
  treated 
  in 
  this 
  way 
  a 
  small 
  number 
  of 
  grubs 
  hatched 
  in 
  confinement 
  

   completed 
  the 
  larval 
  stage 
  by 
  pupating. 
  Figures 
  giving 
  a 
  good 
  indication 
  of 
  the 
  

   length 
  of 
  the 
  larval 
  stage 
  were 
  obtained, 
  too, 
  from 
  grubs 
  hatched 
  in 
  the 
  laboratory 
  

   which 
  died 
  on 
  the 
  point 
  of 
  pupation. 
  After 
  the 
  grub 
  has 
  reached 
  its 
  maximum 
  length, 
  

   when 
  it 
  has 
  a 
  very 
  turgid 
  appearance, 
  it 
  remains 
  of 
  the 
  same 
  size 
  for 
  some 
  little 
  time 
  

   and 
  then 
  empties 
  itself 
  of 
  food, 
  becoming 
  by 
  degrees 
  appreciably 
  shorter 
  and 
  very 
  

   flabb}'. 
  Then 
  about 
  four 
  or 
  five 
  days 
  after 
  this 
  condition 
  is 
  reached, 
  the 
  insect 
  

   pupates. 
  Additional 
  evidence 
  was 
  also 
  procured 
  by 
  measuring, 
  at 
  frequent 
  intervals, 
  

   grubs 
  of 
  different 
  sizes, 
  from 
  very 
  small 
  to 
  very 
  large, 
  brought 
  in 
  from 
  the 
  field 
  and 
  

   fed 
  until 
  death 
  or 
  pupation, 
  and 
  then 
  combining 
  the 
  figures 
  so 
  obtained. 
  The 
  figures 
  

   found 
  in 
  these 
  various 
  ways 
  all 
  point 
  to 
  an 
  average 
  larval 
  period 
  of 
  about 
  100 
  days. 
  

   The 
  shortest 
  time 
  between 
  the 
  hatching 
  of 
  the 
  grubs 
  which 
  were 
  put 
  inside 
  a 
  log 
  

   and 
  the 
  pupation 
  of 
  a 
  grub 
  subsequently 
  recovered 
  from 
  the 
  log 
  was 
  82 
  days. 
  

  

  The 
  Pupa. 
  — 
  The 
  length 
  of 
  the 
  pupal 
  period 
  was 
  ascertained 
  from 
  large 
  grubs 
  

   brought 
  in 
  from 
  the 
  field 
  and 
  from 
  a 
  few 
  grubs 
  which 
  passed 
  the 
  whole 
  larval 
  period 
  

   in 
  the 
  laboratory. 
  For 
  29 
  individuals 
  the 
  average 
  length 
  of 
  the 
  pupal 
  period 
  was 
  

   21 
  days, 
  the 
  extremes 
  being 
  19 
  da\s 
  and 
  28 
  days. 
  In 
  this 
  work 
  on 
  the 
  pupal 
  period 
  

   14 
  pupae 
  died, 
  as 
  well 
  as 
  59 
  larvae 
  in 
  the 
  flabby 
  condition 
  which 
  precedes 
  pupation. 
  

   When 
  the 
  insects 
  were 
  kept 
  in 
  fibrous 
  material 
  a 
  cocoon 
  of 
  this 
  substance 
  was 
  generally 
  

   constructed, 
  but 
  if 
  the 
  material 
  they 
  were 
  living 
  in 
  was 
  powdery 
  no 
  cocoon 
  was 
  made. 
  

   The 
  only 
  place 
  of 
  pupation 
  which 
  I 
  found 
  in 
  the 
  field 
  was 
  inside 
  or 
  just 
  below 
  material 
  

   in 
  which 
  the 
  grubs 
  had 
  fed, 
  but 
  I 
  was 
  not 
  then 
  aware 
  that 
  Leefmans* 
  had 
  found 
  the 
  

   usual 
  place 
  of 
  pupation 
  of 
  0. 
  rhinoceros 
  to 
  be 
  at 
  a 
  depth 
  of 
  12 
  inches 
  in 
  the 
  soil. 
  Large 
  

   grubs 
  in 
  confinement, 
  especially 
  in 
  a 
  few 
  cases 
  when 
  kept 
  in 
  food 
  badly 
  fouled 
  by 
  their 
  

   own 
  faeces, 
  have 
  been 
  found 
  to 
  tear 
  the 
  bodies 
  of 
  their 
  fellows, 
  which 
  points 
  to 
  one 
  

   advantage 
  of 
  the 
  soil 
  as 
  a 
  place 
  for 
  pupation. 
  

  

  The 
  Adults. 
  — 
  As 
  already 
  explained, 
  it 
  was 
  not 
  practicable 
  to 
  keep 
  the 
  adult 
  

   beetles 
  under 
  natural 
  conditions 
  in 
  confinement, 
  but 
  in 
  the 
  conditions 
  described 
  the 
  

   length 
  of 
  adult 
  life 
  was 
  frequently 
  long. 
  Several 
  individuals, 
  of 
  both 
  sexes, 
  brought 
  

   in 
  alive 
  from 
  the 
  field, 
  or 
  becoming 
  adult 
  in 
  the 
  laboratory, 
  lived 
  in 
  confinement 
  for 
  

   more 
  than 
  100 
  days. 
  Many 
  lived 
  more 
  than 
  two 
  months, 
  the 
  maximum 
  having 
  been 
  

   125 
  days, 
  for 
  a 
  male 
  brought 
  in 
  from 
  the 
  field. 
  Several 
  pairs 
  of 
  beetles 
  were 
  taken 
  

   in 
  copula 
  in 
  chopping 
  up 
  decaying 
  logs 
  in 
  the 
  field. 
  

  

  * 
  Leefmans, 
  S., 
  Die 
  Klappcrtor 
  [Oryctes 
  rhinocetos, 
  L.). 
  Meded. 
  Inst. 
  Plantenziekten, 
  

   Buitenzorg, 
  no. 
  41, 
  1920. 
  

  

  