﻿146 
  W. 
  MANSFIELD-ADERS. 
  

  

  It 
  will 
  be 
  seen 
  from 
  this 
  that 
  the 
  length 
  of 
  the 
  larval 
  life 
  is 
  113 
  days, 
  that 
  of 
  the 
  

   pupa 
  18 
  days. 
  

  

  After 
  the 
  mature 
  larvae 
  had 
  built 
  their 
  pupal 
  cell 
  they 
  shrunk 
  considerably 
  in 
  

   size 
  and 
  became 
  very 
  sluggish 
  before 
  pupating 
  ; 
  this 
  period 
  of 
  inertia 
  lasted 
  5 
  days. 
  

  

  Pupae 
  are 
  often 
  found 
  in 
  association 
  with 
  larvae 
  in 
  old 
  coconut 
  trunks, 
  generally 
  

   among 
  the 
  coarse 
  fibres 
  where 
  disintegration 
  has 
  not 
  yet 
  taken 
  place 
  ; 
  the 
  larvae 
  

   prefer 
  the 
  centre, 
  where 
  the 
  fibres 
  have 
  been 
  reduced 
  to 
  the 
  consistency 
  of 
  a 
  warm 
  

   moist 
  debris. 
  

  

  The 
  larvae 
  of 
  Oryctes 
  boas 
  are 
  more 
  usually 
  found 
  in 
  rubbish 
  heaps 
  composed 
  

   of 
  decomposing 
  vegetable 
  matter 
  and 
  manure. 
  I 
  have 
  found 
  manure 
  heaps 
  riddled 
  

   with 
  larvae 
  of 
  all 
  ages 
  ; 
  horse 
  and 
  donkey 
  droppings 
  seem 
  the 
  most 
  attractive. 
  

  

  The 
  following 
  preventive 
  measures 
  have 
  been 
  tried 
  : 
  — 
  

  

  (1). 
  Traps 
  have 
  been 
  set 
  in 
  various 
  localities 
  filled 
  with 
  rotting 
  coconut 
  trunks, 
  

   decaying 
  vegetation, 
  etc. 
  ; 
  the 
  addition 
  of 
  a 
  little 
  horse 
  manure 
  enhances 
  their 
  

   attractiveness 
  and 
  they 
  have 
  given 
  excellent 
  results. 
  

  

  (2). 
  The 
  collection 
  of 
  adults 
  and 
  larvae 
  by 
  natives 
  has 
  been 
  tried 
  in 
  East 
  Africa, 
  

   but 
  the 
  results 
  were 
  not 
  encouraging. 
  

  

  (3). 
  In 
  small 
  plantations 
  the 
  daily 
  examination 
  of 
  all 
  young 
  trees 
  (from 
  2 
  J 
  to 
  

   3 
  years 
  old) 
  for 
  adult 
  beetles 
  should 
  be 
  quite 
  efficacious. 
  The 
  easiest 
  method 
  is 
  to 
  

   insert 
  a 
  small 
  piece 
  of 
  wire 
  with 
  harpoon 
  points 
  into 
  the 
  entrance 
  hole, 
  transfix 
  

   the 
  beetle 
  and 
  withdraw 
  it. 
  After 
  a 
  little 
  experience 
  the 
  palms 
  harbouring 
  beetles 
  

   are 
  easily 
  recognised 
  by 
  the 
  moist 
  tow-like 
  frass 
  protruding 
  from 
  the 
  entry 
  holes. 
  

   Sprinkling 
  dry 
  earth 
  or 
  sand 
  in 
  the 
  crowns 
  of 
  the 
  young 
  trees 
  may 
  possibly 
  act 
  

   as 
  a 
  deterrent 
  to 
  adult 
  beetles. 
  There 
  is 
  no 
  doubt 
  that 
  bare 
  plantations 
  and 
  isolated 
  

   trees 
  are 
  more 
  severely 
  attacked, 
  probably 
  because 
  the 
  beetle 
  being 
  a 
  heavy 
  sluggish 
  

   flier 
  is 
  able 
  to 
  alight 
  more 
  easily 
  on 
  its 
  food-plant 
  under 
  these 
  conditions. 
  The 
  

   planting 
  of 
  some 
  tall 
  bushy 
  catch-crop, 
  such 
  as 
  Cajanus 
  indicus, 
  around 
  the 
  

   plantation 
  might 
  be 
  efficacious. 
  

  

  Some 
  imported 
  larvae 
  infected 
  with 
  a 
  fungus 
  (Metarrhizium 
  anisopliae) 
  were 
  

   received, 
  and 
  it 
  was 
  proved 
  that 
  our 
  local 
  larvae 
  are 
  susceptible 
  to 
  the 
  disease 
  ; 
  

   further, 
  in 
  some 
  control 
  experiments 
  one 
  case 
  of 
  actual 
  indigenous 
  infection 
  was 
  

   found. 
  A 
  long 
  series 
  of 
  experiments 
  with 
  a 
  view 
  to 
  introducing 
  this 
  fungus 
  was 
  

   planned, 
  but 
  owing 
  to 
  unforeseen 
  circumstances 
  all 
  work 
  in 
  this 
  direction 
  was 
  

   abandoned. 
  

  

  I 
  have 
  on 
  several 
  occasions 
  seen 
  young 
  trees 
  suffering 
  from 
  what 
  might 
  be 
  called 
  

   bud-rot. 
  The 
  whole 
  of 
  the 
  crown 
  is 
  easily 
  pulled 
  out 
  leaving 
  a 
  hollow 
  depression 
  

   full 
  of 
  dark 
  fluid 
  with 
  a 
  most 
  foetid 
  odour. 
  It 
  may 
  perhaps 
  be 
  proved 
  later 
  that 
  

   bud-rot 
  is 
  secondary 
  to 
  the 
  attacks 
  of 
  the 
  beetle. 
  

  

  To 
  summarise 
  the 
  above 
  : 
  — 
  The 
  rhinoceros 
  beetles 
  (Oryctes 
  monoceros 
  and 
  0. 
  boas) 
  

   are 
  common 
  throughout 
  Zanzibar 
  and 
  Pemba, 
  and 
  are 
  the 
  most 
  serious 
  pests 
  of 
  the 
  

   coconut 
  industry. 
  Young 
  trees 
  from 
  2 
  \ 
  to 
  3 
  years 
  old 
  are 
  most 
  usually 
  attacked, 
  

   many 
  are 
  killed, 
  others 
  greatly 
  delayed 
  in 
  reaching 
  maturity. 
  Trees 
  in 
  isolated 
  

   positions 
  and 
  on 
  bad 
  soil 
  are 
  more 
  often 
  attacked. 
  Fully 
  matured 
  trees 
  harbour 
  

   adult 
  beetles, 
  but 
  the 
  damage 
  to 
  them 
  is 
  not 
  serious. 
  The 
  most 
  useful 
  preventive 
  

   measure 
  is 
  the 
  trapping 
  of 
  larvae 
  in 
  pits 
  filled 
  with 
  rotting 
  coconut 
  trunks, 
  vegetable 
  

   debris 
  and 
  a 
  little 
  manure. 
  

  

  