﻿SMALL 
  MOTH-BORERS 
  OF 
  SUGAR 
  CANE 
  IN 
  BRITISH 
  GUIANA. 
  459 
  

  

  The 
  first 
  sign 
  of 
  the 
  presence 
  of 
  moth-borers 
  in 
  a 
  field 
  is 
  the 
  appearance 
  in 
  the 
  

   young 
  plants 
  of 
  what 
  is 
  known 
  as 
  " 
  dead 
  -hearts," 
  which 
  term 
  well 
  describes 
  the 
  

   injury, 
  for 
  it 
  is 
  characterised 
  by 
  the 
  young 
  central 
  shoot 
  becoming 
  yellow 
  and 
  finally 
  

   dry, 
  the 
  outer 
  leaves 
  of 
  the 
  plant 
  remaining 
  green, 
  at 
  least 
  for 
  some 
  days 
  afterwards. 
  

   When 
  the 
  young 
  plants 
  are 
  but 
  a 
  few 
  inches 
  high, 
  clusters 
  of 
  eggs 
  of 
  the 
  moth-borer 
  

   may 
  be 
  found 
  on 
  the 
  leaves. 
  These 
  eggs 
  hatch 
  and 
  the 
  young 
  larvae 
  feed 
  on 
  the 
  

   tender 
  leaves 
  of 
  the 
  central 
  shoot 
  for 
  some 
  time. 
  The 
  majority 
  of 
  the 
  larvae 
  perish 
  

   during 
  this 
  period, 
  for 
  usually 
  only 
  one 
  enters 
  the 
  young 
  plant 
  (but 
  occasionally 
  

   three 
  or 
  more). 
  First 
  gnawing 
  its 
  way 
  through 
  the 
  outer 
  stem, 
  the 
  larva 
  gradually 
  

   eats 
  into 
  the 
  interior 
  of 
  the 
  shoot, 
  cutting 
  the 
  tender 
  inner 
  shoot 
  across. 
  It 
  is 
  usually 
  

   some 
  time 
  before 
  the 
  injury 
  is 
  noticed, 
  but 
  cut 
  off 
  from 
  the 
  rest 
  of 
  the 
  plant 
  the 
  

   central 
  leaves 
  gradually 
  begin 
  to 
  wither, 
  and 
  eventually 
  a 
  typical 
  " 
  dead-heart 
  " 
  

   is 
  formed. 
  All 
  dead 
  -hearts 
  in 
  a 
  field 
  may 
  not, 
  however, 
  be 
  caused 
  by 
  moth-borers, 
  

   for 
  young 
  canes 
  are 
  affected 
  in 
  this 
  manner 
  by 
  some 
  other 
  causes, 
  such 
  as 
  by 
  some- 
  

   one 
  accidentally 
  stepping 
  on 
  a 
  young 
  shoot. 
  Castnia 
  licus 
  also 
  produces 
  dead 
  -hearts 
  

   in 
  young 
  canes, 
  as 
  also 
  do 
  the 
  attacks 
  of 
  various 
  fungi 
  in 
  their 
  initial 
  stages, 
  but 
  

   with 
  experience 
  these 
  can 
  soon 
  be 
  recognised. 
  

  

  While 
  the 
  injury 
  to 
  mature 
  cane 
  seldom 
  proves 
  fatal, 
  the 
  damage 
  done 
  is 
  none 
  

   the 
  less 
  important. 
  As 
  previously 
  mentioned, 
  the 
  external 
  signs 
  of 
  moth-borer 
  

   injury 
  are 
  usually 
  nothing 
  more 
  than 
  a 
  few 
  small 
  holes 
  in 
  the 
  rind 
  of 
  the 
  cane, 
  which 
  

   give 
  no 
  adequate 
  idea 
  of 
  the 
  amount 
  of 
  damage 
  incurred. 
  If, 
  however, 
  a 
  stalk 
  is 
  

   split 
  lengthwise, 
  it 
  will 
  be 
  seen 
  that 
  these 
  holes 
  are 
  but 
  the 
  openings 
  of 
  excavations, 
  

   about 
  one-eighth 
  of 
  an 
  inch 
  wide, 
  made 
  by 
  the 
  insects 
  in 
  the 
  interior 
  of 
  the 
  cane. 
  

   In 
  these 
  tunnels 
  the 
  larvae 
  of 
  the 
  moth-borer 
  live, 
  burrowing 
  up 
  and 
  down 
  the 
  stem, 
  

   and 
  a 
  mature 
  cane 
  may 
  be 
  found 
  to 
  harbour 
  two 
  or 
  more 
  such 
  larvae 
  at 
  work 
  in 
  different 
  

   parts 
  of 
  it. 
  More 
  careful 
  examination 
  will 
  often 
  reveal 
  further 
  injuries 
  by 
  borings 
  

   encircling 
  the 
  cane 
  about 
  the 
  joints 
  in 
  such 
  a 
  way 
  that 
  the 
  canes 
  often 
  break 
  at 
  these 
  

   places. 
  Even 
  when 
  such 
  damage 
  occurs 
  only 
  in 
  small 
  quantities 
  it 
  has 
  its 
  ill 
  effects, 
  

   but 
  where 
  a 
  large 
  number 
  of 
  the 
  joints 
  of 
  almost 
  every 
  cane 
  are 
  attacked 
  the 
  damage 
  

   becomes 
  important, 
  and 
  the 
  resultant 
  loss 
  in 
  tonnage 
  of 
  cane 
  and 
  manufactured 
  

   sugar 
  is 
  considerable, 
  

  

  A 
  very 
  important 
  part 
  of 
  the 
  injury 
  occurs 
  to 
  the 
  " 
  seed-piece," 
  or 
  " 
  top 
  " 
  of 
  

   the 
  cane. 
  A 
  large 
  percentage 
  of 
  such 
  " 
  tops 
  " 
  are 
  infested 
  with 
  moth-borer 
  larvae, 
  

   and 
  when 
  these 
  tops 
  are 
  planted 
  without 
  treatment 
  the 
  contained 
  larvae 
  form 
  an 
  

   important 
  source 
  of 
  early 
  infestation 
  to 
  the 
  field. 
  

  

  That 
  borer 
  holes 
  also 
  serve 
  as 
  entrances 
  for 
  fungus 
  diseases 
  has 
  been 
  pointed 
  

   out 
  by 
  other 
  workers. 
  

  

  The 
  injuries 
  caused 
  by 
  the 
  small 
  moth-borers 
  may 
  then 
  well 
  be 
  summarised 
  in 
  

   the 
  words 
  of 
  Holloway 
  and 
  Loftin, 
  who 
  say 
  that 
  " 
  Cane 
  badly 
  bored 
  is 
  found 
  to 
  be 
  

   hard 
  and 
  dry, 
  making 
  it 
  difficult 
  to 
  grind. 
  The 
  growth 
  is 
  checked, 
  and 
  the 
  bored 
  

   stalks 
  are 
  often 
  blown 
  down 
  by 
  a 
  strong 
  wind. 
  The 
  purity 
  of 
  the 
  juice 
  is 
  lowered, 
  

   the 
  tonnage 
  decreased, 
  and 
  the 
  sucrose 
  content 
  materially 
  diminished. 
  The 
  eyes 
  

   are 
  destroyed 
  in 
  many 
  cases, 
  which 
  lessens 
  the 
  value 
  of 
  the 
  infested 
  cane 
  for 
  seed." 
  

  

  For 
  the 
  purpose 
  of 
  obtaining 
  an 
  accurate 
  idea 
  of 
  the 
  amount 
  of 
  damage 
  done 
  by 
  

   these 
  insects 
  careful 
  examinations 
  were 
  made 
  of 
  a 
  number 
  of 
  fields. 
  The 
  method 
  

   adopted 
  was 
  a 
  modification 
  of 
  that 
  used 
  by 
  Holloway 
  and 
  Loftin 
  in 
  their 
  investigations 
  

   on 
  the 
  small 
  moth-borer 
  in 
  the 
  United 
  States 
  of 
  America. 
  

  

  In 
  each 
  field 
  100 
  stalks 
  were 
  examined, 
  taken 
  in 
  five 
  groups 
  of 
  20 
  each 
  at 
  regular 
  

   distances 
  throughout 
  the 
  field. 
  The 
  number 
  of 
  stalks 
  and 
  the 
  number 
  of 
  joints 
  

   damaged 
  were 
  counted 
  and 
  the 
  percentages 
  worked 
  out. 
  In 
  estimating 
  the 
  number 
  

   of 
  joints 
  damaged 
  every 
  joint 
  with 
  a 
  borer 
  hole 
  was 
  considered 
  as 
  damaged, 
  and 
  while 
  

   it 
  is 
  fully 
  recognised 
  that 
  a 
  large 
  number 
  of 
  such 
  holes 
  must 
  be 
  exit 
  holes, 
  in 
  view 
  

   of 
  the 
  fact 
  that 
  a 
  larva 
  seldom 
  bores 
  a 
  single 
  joint, 
  it 
  is 
  considered 
  that 
  this 
  method 
  

   can 
  be 
  taken 
  as 
  fairly 
  representative. 
  From 
  the 
  figures 
  obtained 
  during 
  such 
  

  

  