﻿SMALL 
  MOTH-BORERS 
  OF 
  SUGAR 
  CANE 
  IN 
  BRITISH 
  GUIANA. 
  

  

  463 
  

  

  To 
  test 
  the 
  effect 
  of 
  the 
  immersion 
  of 
  tops 
  on 
  their 
  germination, 
  three 
  punts 
  of 
  

   tops 
  were 
  submerged 
  in 
  a 
  canal 
  and 
  after 
  soaking 
  for 
  72 
  hours 
  the 
  tops 
  were 
  planted 
  

   out 
  in 
  a 
  field. 
  No 
  attempt 
  was 
  made 
  to 
  treat 
  the 
  tops 
  in 
  any 
  manner 
  different 
  

   from 
  the 
  treatment 
  they 
  would 
  receive 
  under 
  practical 
  conditions. 
  The 
  variety 
  

   of 
  cane 
  used 
  was 
  D625. 
  The 
  germination 
  of 
  the 
  soaked 
  tops 
  was 
  then 
  compared 
  

   with 
  the 
  germination 
  of 
  adjacent 
  unsoaked 
  tops. 
  Table 
  IV 
  gives 
  the 
  result 
  of 
  this 
  

   experiment. 
  It 
  will 
  be 
  seen 
  that 
  the 
  soaked 
  tops 
  showed 
  1 
  per 
  cent, 
  less 
  dead 
  -hearts 
  

   than 
  the 
  unsoaked 
  ones 
  ; 
  in 
  addition, 
  the 
  number 
  of 
  shoots 
  per 
  top 
  in 
  the 
  soaked 
  

   tops 
  was 
  2-9 
  as 
  against 
  2-5 
  shoots 
  per 
  top 
  in 
  the 
  unsoaked 
  tops 
  ; 
  and 
  the 
  percentage 
  

   of 
  tops 
  dead 
  is 
  greater 
  in 
  the 
  soaked 
  tops, 
  being 
  10-3 
  per 
  cent, 
  as 
  against 
  9-4 
  per 
  

   cent, 
  in 
  the 
  unsoaked 
  tops. 
  

  

  TABLE 
  IV. 
  

   Germination 
  of 
  Soaked 
  and 
  Unsoaked 
  Tops. 
  

  

  

  No. 
  of 
  

  

  No. 
  of 
  

  

  No. 
  of 
  

  

  Per 
  cent. 
  

  

  Average 
  

  

  Per 
  cent. 
  

  

  Treatment. 
  

  

  Bed. 
  

  

  Tops. 
  

  

  Shoots. 
  

  

  Deadhearts. 
  

  

  No. 
  shoots 
  

   per 
  top. 
  

  

  Tops 
  dead. 
  

  

  Soaked 
  Tops 
  

  

  1 
  

  

  959 
  

  

  2,941 
  

  

  0-9 
  

  

  3-0 
  

  

  4-0 
  

  

  

  2 
  

  

  1,339 
  

  

  4,089 
  

  

  0-4 
  

  

  3-0 
  

  

  6-4 
  

  

  

  3 
  

  

  1,321 
  

  

  4,083 
  

  

  0-4 
  

  

  3-0 
  

  

  S-8 
  

  

  

  4 
  

  

  1,294 
  

  

  3,691 
  

  

  0-6 
  

  

  2-8 
  

  

  14-5 
  

  

  

  5 
  

  

  1,229 
  

  

  3,521 
  

  

  0-3 
  

  

  2-8 
  

  

  19-0 
  

  

  Unsoaked 
  Tops 
  

  

  1 
  

  

  912 
  

  

  1,659 
  

  

  2-2 
  

  

  1-8 
  

  

  7-0 
  

  

  

  2 
  

  

  1,156 
  

  

  2,876 
  

  

  1-7 
  

  

  2-4 
  

  

  5-7 
  

  

  

  3 
  

  

  1,237 
  

  

  2,993 
  

  

  1-0 
  

  

  2-4 
  

  

  7-5 
  

  

  

  4 
  

  

  1,234 
  

  

  3,618 
  

  

  1-4 
  

  

  2-9 
  

  

  13-6 
  

  

  

  5 
  

  

  1,209 
  

  

  3,658 
  

  

  0-7 
  

  

  3-0 
  

  

  13-3 
  

  

  Refuse 
  Tops 
  in 
  Fields. 
  

  

  Probably 
  the 
  most 
  important 
  source 
  of 
  early 
  infestation 
  is 
  to 
  be 
  found 
  in 
  the 
  

   refuse 
  tops 
  left 
  in 
  fields. 
  While 
  the 
  infestation 
  from 
  old 
  banks, 
  and 
  tops 
  used 
  in 
  plant- 
  

   ing, 
  applies 
  principally 
  to 
  fields 
  that 
  are 
  being 
  replanted, 
  the 
  infestation 
  occurring 
  

   from 
  refuse 
  tops 
  takes 
  place 
  in 
  ratoon 
  fields. 
  It 
  also 
  affects 
  plant 
  fields 
  when 
  the 
  

   tops 
  discarded 
  as 
  being 
  unfit 
  for 
  planting 
  are 
  left 
  on 
  the 
  parapets 
  of 
  the 
  fields, 
  if 
  such 
  

   tops 
  have 
  not 
  previously 
  received 
  some 
  treatment 
  for 
  the 
  destruction 
  of 
  the 
  contained 
  

   moth-borers. 
  

  

  It 
  is 
  the 
  usual 
  practice 
  to 
  cut 
  tops 
  for 
  planting 
  whenever 
  a 
  field 
  is 
  being 
  reaped, 
  

   and 
  after 
  the 
  canes 
  have 
  been 
  removed, 
  the 
  tops 
  remain 
  in 
  the 
  fields 
  for 
  periods 
  

   ranging 
  to 
  a 
  couple 
  of 
  weeks 
  or 
  even 
  more 
  before 
  they 
  are 
  collected 
  for 
  planting, 
  

   and 
  even 
  after 
  such 
  collections 
  are 
  made, 
  a 
  large 
  number 
  of 
  tops 
  are 
  still 
  left 
  in 
  the 
  

   fields, 
  either 
  as 
  being 
  unfit 
  for 
  planting 
  or 
  through 
  oversight. 
  

  

  In 
  order 
  to 
  demonstrate 
  this 
  point 
  nine 
  lots 
  of 
  25 
  tops 
  each 
  were 
  collected 
  in 
  the 
  

   field 
  and 
  kept 
  in 
  the 
  laboratory 
  for 
  observation, 
  and 
  after 
  a 
  month 
  were 
  examined 
  

   and 
  their 
  condition 
  noted. 
  The 
  emerging 
  moths 
  were 
  noted, 
  and 
  the 
  tops 
  were 
  

   examined 
  for 
  any 
  moth-borer 
  larvae 
  or 
  other 
  insects 
  they 
  might 
  contain. 
  

  

  These 
  examinations 
  showed 
  that 
  23-1 
  per 
  cent, 
  of 
  the 
  tops 
  contained 
  canella 
  

   larvae, 
  while 
  only 
  5-7 
  per 
  cent, 
  contained 
  saccharalis 
  larvae. 
  Of 
  the 
  total 
  number 
  

   of 
  larvae 
  found 
  over 
  85 
  per 
  cent, 
  were 
  those 
  of 
  canella. 
  Living 
  pupae 
  were 
  contained 
  

   in 
  3-5 
  per 
  cent, 
  of 
  the 
  tops, 
  and 
  moths 
  had 
  emerged 
  from 
  8-4 
  per 
  cent. 
  The 
  borer- 
  

   free 
  tops 
  comprised 
  37 
  per 
  cent, 
  of 
  the 
  total 
  number 
  of 
  tops, 
  and 
  19 
  per 
  cent, 
  possessed 
  

   empty 
  Diatraea 
  borings. 
  Weevils 
  (Metamasius 
  hemipterus, 
  L.) 
  occurred 
  in 
  8-4 
  

   per 
  cent, 
  and 
  termites 
  in 
  3- 
  1 
  per 
  cent., 
  while 
  0-8 
  per 
  cent, 
  of 
  the 
  tops 
  showed 
  mealy- 
  

   bug 
  (Pseudococcus) 
  still 
  alive. 
  

  

  