﻿532 
  

  

  beetles 
  were 
  most 
  prevalent 
  ; 
  6,138 
  egg-batches, 
  each 
  consisting 
  of 
  

   94 
  eggs 
  on 
  an 
  average, 
  were 
  collected. 
  The 
  egg-laying 
  period 
  in 
  

   captivity 
  lasts 
  from 
  3 
  to 
  7 
  days, 
  the 
  shorter 
  period 
  probably 
  being 
  

   more 
  usual 
  in 
  the 
  field. 
  The 
  beetles 
  are 
  active 
  at 
  night, 
  hiding 
  by 
  day 
  

   in 
  the 
  axils 
  of 
  the 
  leaves 
  of 
  sugar-cane 
  and 
  maize 
  and 
  among 
  the 
  leaves 
  

   of 
  pigeon 
  peas 
  and 
  cassava. 
  The 
  eggs 
  were 
  found 
  fastened 
  between 
  

   the 
  wind-spht 
  tips 
  of 
  cane 
  leaves, 
  rarely 
  in 
  the 
  same 
  situation 
  on 
  maize 
  

   and 
  never 
  on 
  other 
  plants. 
  The 
  field 
  toad 
  {Bufo 
  agua) 
  feeds 
  upon 
  

   the 
  beetles. 
  When 
  the 
  eggs 
  hatch 
  the 
  grubs 
  drop 
  to 
  the 
  ground, 
  and 
  

   many 
  are 
  beheved 
  to 
  be 
  destroyed 
  by 
  ants. 
  It 
  is 
  suggested 
  that 
  

   it 
  might 
  be 
  possible 
  to 
  increase 
  the 
  abundance 
  of 
  predaceous 
  ants 
  

   in 
  the 
  cane-fields 
  and 
  even 
  to 
  introduce 
  additional 
  species. 
  The 
  

   newly-hatched 
  grubs 
  penetrate 
  into 
  the 
  ground 
  and 
  feed 
  on 
  the 
  cane- 
  

   roots 
  ; 
  later, 
  from 
  December 
  to 
  February, 
  they 
  attack 
  the 
  stem 
  of 
  

   the 
  cane 
  stool 
  underground, 
  causing 
  the 
  canes 
  to 
  wither 
  as 
  if 
  killed 
  

   by 
  drought. 
  The 
  root 
  fungus 
  {Marasmius 
  sacchari) 
  also 
  produces 
  

   this 
  result 
  and 
  is 
  often 
  found 
  together 
  with 
  the 
  root-borer. 
  

   In 
  many 
  cases 
  the 
  fungus 
  is 
  secondary 
  in 
  its 
  attack 
  and 
  in 
  its 
  efiect. 
  

   The 
  practice 
  of 
  digging 
  cane-stumps 
  immediately 
  after 
  reaping 
  

   the 
  canes 
  is 
  again 
  recommended, 
  but 
  it 
  is 
  stated 
  to 
  have 
  no 
  

   value 
  if 
  the 
  stumps 
  are 
  left 
  till 
  they 
  begin 
  to 
  dry 
  out, 
  because 
  the 
  

   grubs 
  leave 
  them 
  and 
  penetrate 
  into 
  the 
  soil, 
  where 
  they 
  may 
  he 
  dormant 
  

   for 
  some 
  time. 
  This 
  dormant 
  period 
  has 
  been 
  studied, 
  and 
  grubs 
  

   have 
  lived 
  in 
  captivity 
  without 
  feeding 
  for 
  periods 
  up 
  to 
  334 
  days. 
  

   This 
  abihty 
  on 
  the 
  part 
  of 
  Diaprepes 
  grubs 
  has 
  an 
  important 
  bearing 
  

   on 
  the 
  problem 
  of 
  control, 
  and 
  explains 
  the 
  attacks 
  on 
  young 
  canes 
  

   when 
  these 
  follow 
  in 
  the 
  same 
  fields 
  without 
  an 
  intermediate 
  crop. 
  

   No 
  insect 
  parasite 
  of 
  the 
  root 
  borer 
  has 
  been 
  found, 
  in 
  spite 
  of 
  careful 
  

   search, 
  but 
  two 
  grubs 
  were 
  found 
  attacked 
  by 
  the 
  green 
  muscardine 
  

   fungus 
  (Metarrhizium 
  anisopliae), 
  and 
  trials 
  are 
  being 
  made 
  with 
  this 
  

   fungus. 
  

  

  The 
  cane 
  leaf 
  beetle 
  (Myochrous 
  armatus, 
  Baly) 
  is 
  a 
  potential 
  

   rather 
  than 
  an 
  actual 
  pest. 
  Phy 
  talus 
  smithi 
  is 
  known 
  in 
  Barbados 
  as 
  

   the 
  brown 
  hard-back, 
  and 
  it 
  has 
  also 
  been 
  called 
  the 
  Mauritius 
  hard- 
  

   back, 
  since 
  it 
  is 
  a 
  serious 
  pest 
  in 
  that 
  island 
  [see 
  this 
  Review, 
  Ser. 
  A, 
  

   i, 
  p. 
  28]. 
  Nowell 
  has 
  investigated 
  the 
  life-history 
  and 
  habits 
  of 
  this 
  

   I)eetle 
  and 
  its 
  parasite, 
  Tiphia 
  parallela, 
  [see 
  this 
  Review, 
  Ser. 
  A, 
  i, 
  

   p. 
  254] 
  and 
  supphes 
  the 
  following 
  information. 
  The 
  female 
  Phy 
  talus 
  

   deposits 
  her 
  eggs 
  singly 
  at 
  a 
  depth 
  of 
  4-6 
  inches 
  in 
  the 
  ground 
  ; 
  the 
  

   hfe-cycle 
  occupies 
  from 
  265 
  to 
  333 
  days. 
  The 
  adults 
  are 
  most 
  abundant 
  

   in 
  May 
  or 
  June 
  ; 
  though 
  not 
  much 
  attracted 
  to 
  fight 
  they 
  sometimes 
  

   fly 
  into 
  houses 
  and 
  are 
  caught 
  in 
  fight 
  traps. 
  Tiphia 
  parallela, 
  is 
  a 
  

   very 
  efl&cient 
  parasite 
  of 
  this 
  pest 
  ; 
  its 
  fife-cycle 
  occupies 
  about 
  50 
  days 
  

   and 
  eacfi 
  female 
  lays 
  about 
  70 
  eggs. 
  This 
  Tiphia 
  does 
  not 
  seem 
  to 
  

   be 
  generally 
  distributed 
  over 
  Barbados, 
  as 
  Phytalus 
  occasionaUy 
  

   appears 
  in 
  numbers 
  without 
  any 
  Tiphia 
  being 
  found. 
  The 
  ordinary 
  

   hard-back 
  {Ligyrus 
  tumulosus) 
  is 
  parasitised 
  by 
  Dielis 
  dorsata 
  in 
  a 
  

   similar 
  way, 
  the 
  chief 
  differences 
  being 
  that 
  the 
  sting 
  of 
  the 
  Dielis 
  

   female 
  produces 
  a 
  fatal 
  degree 
  of 
  paralysis 
  in 
  the 
  larva 
  and 
  the 
  Dielis 
  

   €gg 
  is 
  deposited 
  on 
  the 
  ventral 
  instead 
  of 
  the 
  dorsal 
  surface. 
  

  

  The 
  cane-fly 
  (Delphax 
  saccharivora) 
  is 
  reported 
  to 
  have 
  attacked 
  

   both 
  old 
  and 
  young 
  canes, 
  but 
  w^as 
  apparently 
  controlled 
  by 
  natural 
  

   enemies, 
  principally 
  Chrysopa 
  spp. 
  The 
  rust-mite 
  of 
  canes 
  (Tarsonernvs 
  

  

  