﻿460 
  

  

  L. 
  D. 
  CLEARE, 
  JR. 
  

  

  examinations 
  it 
  has 
  been 
  found 
  that 
  an 
  average 
  infestation 
  of 
  93 
  per 
  cent, 
  of 
  stalks 
  

   and 
  28 
  per 
  cent, 
  of 
  joints 
  attacked 
  is 
  not 
  unusual. 
  While 
  the 
  percentage 
  of 
  stalks 
  

   damaged 
  gives 
  some 
  idea 
  of 
  the 
  amount 
  of 
  injury, 
  a 
  more 
  accurate 
  estimate 
  of 
  the 
  

   loss 
  caused 
  by 
  the 
  insects 
  can 
  be 
  obtained 
  when 
  the 
  percentage 
  of 
  joints 
  damaged 
  

   is 
  also 
  taken 
  into 
  consideration. 
  

  

  Table 
  I 
  gives 
  the 
  infestation 
  of 
  stalks 
  and 
  joints 
  in 
  plant-canes, 
  1st, 
  2nd, 
  and 
  

  

  3rd 
  ratoons 
  and 
  old 
  canes, 
  on 
  two 
  plantations. 
  

  

  ( 
  

  

  TABLE 
  I. 
  

  

  Infestation 
  of 
  Plant 
  and 
  Ratoon 
  Canes. 
  

  

  

  Plant 
  Canes. 
  

  

  1st 
  Ratoons. 
  

  

  2nd 
  Ratoons. 
  

  

  3rd 
  Ratoons. 
  

  

  Old 
  Canes. 
  

  

  

  Stalks. 
  

  

  Joints. 
  

  

  Stalks. 
  

  

  Joints. 
  

  

  Stalks. 
  \ 
  Joints. 
  

  

  Stalks. 
  

  

  Joints. 
  

  

  Stalks. 
  

  

  Joints. 
  

  

  No. 
  1 
  

   No. 
  2 
  

  

  83-8 
  

   90-0 
  

  

  17-5 
  

   24-3 
  

  

  94-2 
  

   96-0 
  

  

  26-9 
  

   26-3 
  

  

  94-5 
  

  

  21-7 
  

  

  87-5 
  

   91-0 
  

  

  19-0 
  

   31-3 
  

  

  93-5 
  

   95-2 
  

  

  19-0 
  

   31-4 
  

  

  Average 
  

  

  86-9 
  

  

  20-9 
  

  

  95-1 
  

  

  26-6 
  

  

  94-5 
  

  

  21-7 
  

  

  89-2 
  

  

  25-1 
  

  

  99-3 
  

  

  25-2 
  

  

  The 
  lowest 
  infestation 
  was 
  11-0 
  per 
  cent, 
  of 
  joints 
  attacked 
  in 
  a 
  field 
  of 
  plant- 
  

   canes, 
  while 
  the 
  highest 
  infestation 
  was 
  in 
  a 
  field 
  of 
  old 
  canes, 
  of 
  some 
  nine 
  years 
  

   standing, 
  which 
  showed 
  43-2 
  per 
  cent, 
  of 
  the 
  joints 
  attacked. 
  

  

  The 
  question 
  of 
  the 
  relationship 
  of 
  the 
  ratooning 
  period 
  to 
  infestation 
  by 
  moth- 
  

   borers 
  will 
  be 
  dealt 
  with 
  elsewhere. 
  

  

  A 
  very 
  important 
  part 
  of 
  the 
  injury 
  occasioned 
  by 
  small 
  moth-borers 
  is 
  that 
  which 
  

   occurs 
  to 
  the 
  " 
  seed-piece 
  " 
  or 
  " 
  top 
  " 
  of 
  the 
  cane. 
  When 
  the 
  cane 
  has 
  reached 
  

   maturity 
  it 
  is 
  this 
  part 
  of 
  the 
  plant 
  that 
  principally 
  harbours 
  moth-borer 
  larvae, 
  

   and 
  if 
  such 
  tops 
  are 
  planted 
  without 
  treatment, 
  as 
  is 
  the 
  general 
  rule, 
  a 
  large 
  proportion 
  

   of 
  the 
  larvae 
  they 
  contain 
  continue 
  their 
  development 
  in 
  the 
  tops 
  after 
  planting, 
  

   either 
  directly 
  entering 
  the 
  young 
  shoots 
  as 
  they 
  spring 
  from 
  the 
  top, 
  or 
  emerging 
  

   as 
  moths 
  and 
  forming 
  a 
  source 
  of 
  early 
  infestation 
  for 
  the 
  young 
  plants. 
  Many 
  

   hundreds 
  of 
  tops 
  examined 
  showed 
  that 
  an 
  average 
  of 
  14-2 
  per 
  cent, 
  are 
  so 
  infested. 
  

   In 
  examining 
  them, 
  only 
  tops 
  that 
  actually 
  contained 
  larvae 
  or 
  pupae 
  at 
  the 
  time 
  

   of 
  examination 
  were 
  considered 
  affected. 
  Tops 
  that 
  had 
  been 
  bored 
  but 
  at 
  the 
  

   time 
  contained 
  neither 
  larvae 
  nor 
  pupae 
  were 
  considered 
  as 
  unaffected 
  and 
  counted 
  

   as 
  borer-free 
  tops. 
  Of 
  the 
  unaffected 
  tops 
  35-2 
  per 
  cent, 
  showed 
  such 
  borings, 
  so 
  

   that 
  only 
  50-4 
  per 
  cent, 
  of 
  the 
  tops 
  were 
  sound. 
  Of 
  the 
  infested 
  tops 
  9-0 
  per 
  cent, 
  

   were 
  found 
  to 
  contain 
  canella 
  larvae, 
  3-7 
  per 
  cent, 
  saccharalis 
  larvae, 
  and 
  1-5 
  per 
  

   cent, 
  pupae. 
  

  

  Factors 
  influencing 
  the 
  Prevalence 
  of 
  the 
  Moths. 
  

  

  Early 
  Infestation 
  of 
  Plant 
  Fields 
  from 
  " 
  Old 
  Banks."* 
  

  

  Artificial 
  dissemination 
  plays 
  a 
  very 
  important 
  part 
  in 
  the 
  early 
  infestation 
  of 
  

   fields, 
  probably 
  the 
  most 
  important 
  source 
  in 
  plant 
  fields 
  being 
  the 
  " 
  old 
  banks,"* 
  or 
  

   " 
  false 
  rows," 
  as 
  they 
  are 
  sometimes 
  called. 
  When 
  a 
  field 
  is 
  replanted 
  this 
  is 
  done 
  

   between 
  the 
  rows 
  of 
  the 
  old 
  crop, 
  and 
  the 
  old 
  stools 
  are 
  not 
  forked 
  out 
  till 
  later 
  ; 
  

   consequently 
  shoots 
  spring 
  from 
  them, 
  forming 
  the 
  " 
  false 
  row." 
  Very 
  often 
  these 
  

   attain 
  the 
  height 
  of 
  three 
  feet 
  before 
  the 
  tops 
  have 
  sprung 
  more 
  than 
  six 
  inches 
  

   (Plate 
  xxiv, 
  fig. 
  1). 
  On 
  occasions 
  it 
  has 
  been 
  observed 
  that 
  the 
  old 
  stools 
  attained 
  

   this 
  height 
  even 
  before 
  replanting 
  was 
  commenced, 
  and 
  it 
  was 
  necessary 
  to 
  weed 
  

   the 
  field 
  preliminary 
  to 
  planting. 
  

  

  