﻿INSECTS 
  IN 
  SUGAR-CANE 
  PLANTATIONS 
  IN 
  FIJI. 
  27 
  

  

  The 
  finely 
  reticulated, 
  elongate 
  oval 
  eggs 
  are 
  on 
  an 
  average 
  about 
  2 
  '5 
  mm. 
  in 
  

   length, 
  and 
  1*25 
  mm. 
  in 
  breadth 
  when 
  newly 
  laid, 
  but 
  the 
  egg 
  increases 
  in 
  size 
  as 
  

   the 
  incubation 
  period 
  advances, 
  and 
  just 
  before 
  hatching 
  it 
  is 
  spherical 
  rather 
  

   than 
  elongate 
  oval, 
  the 
  diameter 
  being 
  approximately 
  3*5 
  mm. 
  The 
  eggs 
  are 
  laid 
  

   singly 
  at 
  a 
  depth 
  of 
  15 
  to 
  20 
  inches, 
  having 
  an 
  average 
  incubation 
  period 
  of 
  31 
  

   days, 
  the 
  maximum 
  and 
  minimum 
  being 
  34 
  and 
  28 
  days 
  respectively. 
  Dissection 
  

   shows 
  that 
  each 
  of 
  the 
  paired 
  ovaries 
  consists 
  of 
  six 
  tubes 
  each 
  producing 
  three 
  

   eggs, 
  the 
  maximum 
  number 
  a 
  female 
  lays 
  being 
  36, 
  although 
  in 
  captivity 
  it 
  is 
  

   usually 
  considerably 
  less. 
  The 
  eggs 
  are 
  laid 
  from 
  May 
  to 
  September 
  inclusive, 
  

   the 
  chief 
  egg-laying 
  months 
  being 
  June 
  and 
  July. 
  

  

  The 
  grubs 
  feed 
  on 
  both 
  living 
  and 
  decaying 
  vegetable 
  matter 
  in 
  the 
  soil, 
  very 
  

   large 
  quantities 
  of 
  soil 
  being 
  swallowed 
  in 
  order 
  to 
  extract 
  this 
  ; 
  but 
  living 
  vegetable 
  

   matter, 
  such 
  as 
  cane 
  roots, 
  is 
  also 
  attacked, 
  and 
  in 
  this 
  respect 
  the 
  damage 
  is 
  

   particularly 
  severe 
  in 
  January, 
  February 
  and 
  March, 
  i.e., 
  when 
  the 
  grubs 
  are 
  well 
  

   grown. 
  When 
  full-grown 
  the 
  white 
  grub 
  averages 
  27 
  mm. 
  in 
  length 
  and 
  6 
  mm. 
  

   in 
  breadth 
  ; 
  the 
  body 
  colour 
  is 
  creamy 
  white, 
  with 
  the 
  exception 
  of 
  the 
  last 
  

   abdominal 
  segment, 
  which 
  appears 
  greyish 
  black 
  as 
  a 
  result 
  of 
  the 
  contents 
  of 
  

   the 
  alimentary 
  tract 
  showing 
  through 
  the 
  skin. 
  The 
  great 
  majority 
  of 
  the 
  grubs 
  

   are 
  found 
  within 
  six 
  or 
  seven 
  inches 
  of 
  the 
  surface 
  of 
  the 
  soil 
  all 
  the 
  year 
  round, 
  

   and 
  so 
  they 
  are 
  always 
  within 
  reach 
  of 
  the 
  plough. 
  

  

  In 
  April, 
  or 
  even 
  earlier 
  in 
  some 
  cases, 
  the 
  grubs 
  enter 
  the 
  pre-pupal 
  stage 
  which 
  

   lasts 
  for 
  a 
  couple 
  of 
  weeks, 
  at 
  the 
  end 
  of 
  which 
  time 
  the 
  pupa 
  is 
  formed 
  in 
  an 
  earthern 
  

   cell 
  at 
  a 
  depth 
  of 
  6 
  to 
  18 
  inches 
  below 
  the 
  surface. 
  The 
  pupa 
  averages 
  19 
  mm. 
  

   in 
  length 
  and 
  8 
  mm. 
  in 
  breadth 
  ; 
  the 
  pupal 
  period 
  lasts 
  for 
  31 
  days. 
  Pupae 
  are 
  

   found 
  from 
  April 
  to 
  September, 
  but 
  are 
  most 
  plentiful 
  in 
  April 
  and 
  May. 
  

  

  The 
  beetles 
  do 
  not 
  leave 
  the 
  soil 
  immediately 
  after 
  the 
  transformation 
  from 
  

   pupa 
  to 
  beetles, 
  but 
  lie 
  resting 
  in 
  their 
  earthern 
  cells 
  for 
  two 
  or 
  three 
  weeks 
  before 
  

   emerging 
  to 
  feed 
  and 
  mate. 
  Beetles 
  have 
  been 
  found 
  in 
  the 
  soil 
  on 
  7th 
  February, 
  

   but 
  this 
  is 
  unusually 
  early, 
  for 
  they 
  do 
  not 
  reach 
  their 
  maximum 
  abundance 
  until 
  

   June. 
  During 
  the 
  swarming 
  season 
  they 
  are 
  found 
  in 
  thousands 
  on 
  their 
  food- 
  

   plants, 
  the 
  chief 
  of 
  which 
  are 
  acacias, 
  guavas, 
  coconuts 
  and 
  cane, 
  but 
  for 
  the 
  

   purpose 
  of 
  mating 
  they 
  will 
  also 
  swarm 
  in 
  large 
  numbers 
  on 
  any 
  prominent 
  object 
  

   such 
  as 
  windmills, 
  telephone 
  poles 
  or 
  large 
  trees. 
  In 
  the 
  swarming 
  season 
  the 
  

   beetles 
  emerge 
  about 
  twenty 
  minutes 
  after 
  sunset, 
  and 
  mating 
  proceeds 
  for 
  two 
  

   hours, 
  after 
  which 
  they 
  settle 
  down 
  on 
  their 
  food-plants, 
  where 
  some 
  of 
  them 
  feed, 
  

   while 
  others 
  remain 
  quite 
  inactive 
  ; 
  shortly 
  before 
  sunrise 
  they 
  return 
  to 
  the 
  soil 
  

   or 
  to 
  their 
  hiding 
  places 
  under 
  cane 
  trash 
  and 
  fallen 
  leaves. 
  The 
  most 
  prominent 
  

   feature 
  of 
  this 
  return 
  to 
  the 
  soil 
  is 
  the 
  rapidity 
  with 
  which 
  it 
  is 
  accomplished, 
  as 
  

   not 
  a 
  single 
  beetle 
  is 
  to 
  be 
  seen 
  a 
  couple 
  of 
  minutes 
  after 
  the 
  first 
  one 
  has 
  taken 
  

   flight. 
  

  

  The 
  beetle 
  is 
  reddish 
  brown 
  in 
  colour, 
  and 
  is 
  clothed 
  with 
  very 
  small 
  yellowish 
  

   setae, 
  except 
  on 
  the 
  breast, 
  which 
  is 
  covered 
  with 
  long 
  yellow 
  hairs. 
  The 
  average 
  

   length 
  is 
  17 
  mm. 
  and 
  the 
  average 
  maximum 
  breadth 
  9 
  mm. 
  

  

  The 
  life-history 
  may 
  be 
  summarised 
  as 
  follows 
  : 
  — 
  The 
  female 
  lays 
  twenty 
  to 
  

   thirty 
  eggs 
  singly 
  in 
  sandy 
  soil 
  in 
  June 
  and 
  July 
  at 
  a 
  depth 
  of 
  15 
  to 
  20 
  inches, 
  and 
  

   after 
  an 
  incubation 
  period 
  of 
  28 
  to 
  34 
  days 
  the 
  grubs 
  emerge 
  and 
  feed 
  on 
  humus 
  and 
  

  

  