﻿61 
  

  

  birds. 
  In 
  Trinidad 
  the 
  cane 
  fields 
  seem 
  deficient 
  in 
  the 
  various 
  native 
  

   insects 
  and 
  spiders 
  which 
  prey 
  on 
  the 
  adult 
  froghopper, 
  and 
  the 
  author 
  

   suggests 
  that 
  in 
  the 
  middle 
  of 
  large 
  fields 
  a 
  small 
  plot 
  of 
  cane 
  be 
  left 
  

   to 
  provide 
  a 
  refuge 
  and 
  breeding 
  place 
  for 
  them. 
  Carbon 
  bisulphide 
  

   is 
  unsatisfactory 
  as 
  an 
  insecticide 
  for 
  froghopper 
  nymphs 
  under 
  field 
  

   conditions, 
  as 
  they 
  are, 
  as 
  a 
  rule, 
  hermetically 
  sealed 
  on 
  the 
  rootlet 
  

   with 
  spittle, 
  which 
  the 
  fumes 
  can 
  only 
  penetrate 
  with 
  difficulty. 
  To 
  

   be 
  effective, 
  a 
  very 
  large 
  quantity 
  of 
  the 
  chemical 
  would 
  be 
  necessary 
  

   and 
  the 
  expense 
  would 
  be 
  prohibitive. 
  If 
  trash 
  is 
  left 
  as 
  long 
  as 
  

   possible 
  on 
  the 
  fields 
  the 
  parasites 
  have 
  a 
  chance 
  of 
  hatching 
  and 
  

   escaping, 
  and 
  the 
  author 
  believes 
  that 
  if 
  the 
  trash 
  is 
  left 
  lying 
  about 
  

   and 
  not 
  piled 
  up, 
  it 
  is 
  unfavourable 
  rather 
  than 
  otherwise 
  to 
  the 
  frog- 
  

   hopper 
  eggs. 
  There 
  are 
  three 
  artificial 
  methods 
  of 
  control, 
  apart 
  from 
  

   the 
  Green 
  Muscardine 
  fungus, 
  which 
  promise 
  some 
  measure 
  of 
  success, 
  

   and 
  which 
  are 
  being 
  tried 
  on 
  a 
  large 
  scale 
  at 
  Chagunas 
  : 
  — 
  (1) 
  Using 
  

   Nitrolim 
  as 
  a 
  manure 
  primarily, 
  and 
  secondarily 
  against 
  the 
  froghopper 
  

   nymphs 
  ; 
  it 
  is 
  applied 
  to 
  the 
  roots 
  of 
  the 
  canes 
  by 
  the 
  usual 
  dusters. 
  

   (2) 
  Kerosene-Lysol 
  emulsion 
  against 
  the 
  adult 
  froghopper. 
  This 
  is 
  

   very 
  ei?ective 
  if 
  properly 
  applied, 
  as 
  the 
  insect 
  is 
  killed 
  in 
  a 
  few 
  minutes 
  

   if 
  touched 
  at 
  all 
  by 
  the 
  liquid. 
  Lysol 
  (3 
  oz.) 
  and 
  kerosene 
  (9 
  oz.) 
  are 
  

   mixed 
  in 
  the 
  measure, 
  and 
  then 
  stirred 
  up 
  in 
  4 
  gallons 
  of 
  soft 
  water. 
  

   This 
  2 
  per 
  cent, 
  emulsion 
  remains 
  emulsified 
  indefinitely. 
  Kerosene, 
  

   and 
  water 
  is 
  even 
  more 
  effective, 
  but 
  unless 
  continually 
  shaken 
  up 
  will 
  

   separate 
  almost 
  immediately, 
  and 
  is 
  therefore 
  unsafe 
  for 
  coolie 
  use. 
  

   When 
  making 
  the 
  experiments 
  an 
  ordinary 
  whisky 
  bottle 
  (27 
  oz.) 
  was 
  

   fitted 
  with 
  a 
  cork 
  through 
  which 
  passes 
  a 
  short 
  piece 
  of 
  glass 
  of 
  J 
  inch 
  

   bore, 
  so 
  that 
  it 
  emits 
  a 
  jet, 
  not 
  a 
  spray. 
  A 
  little 
  of 
  the 
  emulsion 
  is 
  

   shaken 
  into 
  the 
  leaf 
  sheaths 
  where 
  the 
  insects 
  are 
  hiding. 
  This 
  is 
  best 
  

   done 
  when 
  the 
  canes 
  are 
  small 
  ; 
  when 
  they 
  are 
  more 
  than 
  breast-high 
  

   it 
  will 
  be 
  far 
  more 
  difficult 
  to 
  apply 
  the 
  liquid. 
  (3) 
  After 
  each 
  brood 
  

   of 
  adult 
  froghoppers, 
  the 
  old 
  leaves 
  on 
  the 
  growing 
  canes 
  should 
  be 
  

   examined 
  for 
  eggs, 
  and 
  if 
  any 
  numbers 
  are 
  found, 
  the 
  canes 
  should 
  be 
  

   trashed 
  and 
  the 
  trash 
  taken 
  at 
  once 
  to 
  the 
  cattle 
  sheds 
  for 
  use 
  as 
  litter, 
  

   when 
  the 
  eggs 
  will 
  soon 
  be 
  destroyed. 
  If 
  the 
  sheds 
  are 
  unable 
  to 
  deal 
  

   with 
  all 
  the 
  trash 
  at 
  once, 
  it 
  should 
  be 
  stacked 
  on 
  bare 
  ground 
  away 
  

   from 
  vegetation 
  until 
  it 
  can 
  be 
  used. 
  On 
  some 
  estates 
  it 
  might 
  be 
  

   possible 
  to 
  spread 
  it 
  on 
  a 
  piece 
  of 
  waste 
  ground 
  and 
  fold 
  cattle 
  tem- 
  

   porarily 
  upon 
  it. 
  

  

  The 
  author 
  insists 
  upon 
  the 
  importance 
  of 
  directing 
  remedial 
  

   measures 
  especially 
  against 
  the 
  first 
  broods 
  of 
  the 
  insect 
  in 
  the 
  spring, 
  

   but 
  meanwhile 
  (Aug. 
  1913) 
  he 
  advises 
  the 
  continued 
  and 
  extended 
  use 
  

   of 
  trap 
  lights 
  for 
  catching 
  the 
  adults, 
  for 
  the 
  damage 
  done 
  to 
  the 
  cane 
  by 
  

   the 
  sucking 
  of 
  large 
  numbers 
  of 
  adults 
  on 
  the 
  leaves 
  is 
  very 
  great. 
  It 
  is 
  

   supposed 
  that 
  a 
  loss 
  of 
  111 
  gallons 
  of 
  sap 
  per 
  acre 
  is 
  a 
  very 
  conservative 
  

   estimate, 
  as 
  many 
  of 
  the 
  factors 
  used 
  in 
  the 
  calculation 
  were 
  kept 
  very 
  

   low. 
  Observations 
  relating 
  to 
  the 
  feeding 
  of 
  the 
  adult 
  froghopper 
  show 
  

   that 
  in 
  one 
  hour's 
  continuous 
  sucking 
  it 
  voids 
  about 
  0*75 
  c.c. 
  of 
  liquid 
  

   excrement. 
  There 
  is 
  now 
  little 
  doubt 
  that 
  the 
  Syrphid 
  larva, 
  noted 
  by 
  

   Gough 
  in 
  1910, 
  is 
  largely 
  responsible 
  for 
  the 
  diminished 
  numbers 
  of 
  

   the 
  third 
  froghopper 
  brood. 
  During 
  the 
  larval 
  stage 
  each 
  of 
  them 
  kills 
  

   several 
  froghopper 
  nymphs, 
  probably 
  a 
  dozen 
  at 
  least. 
  This 
  Syrphid 
  

   will 
  be 
  found 
  in 
  all 
  localities, 
  wet 
  or 
  dry, 
  where 
  the 
  froghopper 
  exists. 
  

  

  