﻿INSECTS 
  IN 
  SUGAR-CANE 
  PLANTATIONS 
  IN 
  FIJI. 
  ol 
  

  

  The 
  Sugar-Cane 
  Wireworm 
  (Simodactylus 
  cinnamomeus, 
  Boisd.) 
  (fig. 
  6). 
  

  

  The 
  following 
  species 
  of 
  wireworms 
  have 
  been 
  found 
  in 
  the 
  soils 
  of 
  the 
  Fijian 
  cane- 
  

   fields 
  : 
  Simodactylus 
  cinnamomeus, 
  Boisd. 
  , 
  Lacon 
  siricticollis, 
  Fairm. 
  , 
  and 
  Monocre- 
  

   pidius 
  pallipes, 
  Esch. 
  The 
  first 
  two 
  species, 
  but 
  more 
  particularly 
  S. 
  cinnamomeus, 
  

   are 
  very 
  destructive 
  to 
  young 
  cane 
  plants, 
  while 
  the 
  third 
  is 
  distinctly 
  beneficial, 
  as 
  

   it 
  is 
  a 
  very 
  formidable 
  enemy 
  of 
  the 
  white 
  grubs 
  of 
  Rhopaea 
  vestita. 
  

  

  S. 
  cinnamomeus 
  is 
  by 
  far 
  the 
  commonest 
  of 
  the 
  three 
  species, 
  being 
  found 
  in 
  all 
  

   five 
  types 
  of 
  soil, 
  but 
  reaching 
  its 
  maximum 
  abundance 
  in 
  the 
  rich 
  low-lying 
  fiats, 
  

   where 
  it 
  frequently 
  occurs 
  in 
  enormous 
  numbers. 
  

  

  The 
  full-grown 
  wireworm 
  is 
  sub-cylindrical 
  in 
  shape, 
  and 
  measures 
  25 
  mm. 
  in 
  length 
  

   and 
  2 
  mm. 
  in 
  breadth. 
  The 
  dorsum 
  varies 
  in 
  colour 
  from 
  a 
  very 
  light 
  brown 
  to 
  a 
  

   blackish 
  brown, 
  an 
  intermediate 
  shade 
  being 
  typical 
  ; 
  the 
  pleura 
  and 
  venter 
  are 
  pale 
  

   brown. 
  The 
  newly 
  hatched 
  wireworm 
  measures 
  2 
  mm. 
  in 
  length, 
  and 
  for 
  a 
  few 
  days 
  

   is 
  of 
  a 
  semi-opaque 
  white 
  colour, 
  but 
  rapidly 
  assumes 
  a 
  faint 
  brown 
  tint. 
  It 
  grows 
  

   very 
  slowly, 
  the 
  available 
  evidence 
  pointing 
  to 
  a 
  larval 
  period 
  of 
  not 
  less 
  than 
  three 
  

   years. 
  The 
  older 
  wireworms 
  under 
  laboratory 
  conditions 
  moult 
  every 
  ten 
  or 
  twelve 
  

   weeks. 
  

  

  Fig 
  6. 
  Simodactylus 
  cinna- 
  

   momeus, 
  Boisd., 
  X 
  3. 
  

  

  This 
  wireworm 
  pupates 
  in 
  a 
  small 
  earthen 
  cell 
  with 
  smoothly 
  plastered 
  inner 
  walls, 
  

   and 
  ten 
  or 
  eleven 
  days 
  later 
  assumes 
  the 
  adult 
  form. 
  The 
  beetle 
  does 
  not 
  leave 
  the 
  

   soil 
  immediately 
  after 
  its 
  transformation, 
  but 
  generally 
  rests 
  in 
  its 
  cell 
  for 
  a 
  fortnight 
  

   or 
  longer 
  before 
  emerging 
  to 
  feed 
  and 
  mate. 
  

  

  The 
  beetles 
  are 
  inactive 
  during 
  the 
  day. 
  and 
  may 
  be 
  found 
  in 
  large 
  numbers 
  hiding 
  

   behind 
  the 
  leaf-sheaths 
  of 
  cane, 
  maize 
  and 
  various 
  weeds, 
  and 
  in 
  maize 
  cobs, 
  they 
  

   also 
  hide 
  under 
  lumps 
  of 
  earth 
  on 
  the 
  surface 
  of 
  the 
  soil. 
  Towards 
  dark 
  they 
  become 
  

   more 
  active 
  and 
  leave 
  their 
  hiding 
  places. 
  

  

  The 
  females 
  lay 
  their 
  eggs 
  in 
  clusters 
  or 
  strings 
  in 
  small 
  cavities 
  formed 
  in 
  lumps 
  

   of 
  moist 
  friable 
  soil, 
  the 
  number 
  of 
  eggs 
  per 
  cluster 
  or 
  string 
  varying 
  from 
  five 
  to 
  

   fifty. 
  The 
  elongate 
  oval 
  eggs 
  are 
  pearly 
  white 
  in 
  colour 
  and 
  when 
  newly 
  laid 
  measure 
  

   *7 
  mm. 
  in 
  length 
  and 
  *3 
  mm. 
  in 
  breadth 
  ; 
  in 
  the 
  cool 
  months 
  of 
  June 
  and 
  July 
  the 
  

   incubation 
  period 
  varies 
  from 
  16 
  to 
  19 
  days. 
  

  

  