﻿95 
  

  

  appear 
  after 
  rain, 
  and 
  feed 
  during 
  the 
  morning 
  and 
  evening. 
  The 
  

   methods 
  of 
  controUing 
  locusts 
  which 
  have 
  been 
  adopted 
  in 
  the 
  Sudan 
  

   include 
  the 
  following 
  : 
  (1) 
  Collection 
  and 
  destruction 
  of 
  eggs 
  and 
  

   hoppers 
  ; 
  these 
  methods 
  need 
  a 
  large 
  amount 
  of 
  labour 
  and 
  the 
  

   collecting 
  of 
  eggs 
  may 
  be 
  exceedingly 
  arduous; 
  (2) 
  scaring 
  away 
  of 
  

   adults 
  by 
  noises 
  ; 
  (3) 
  the 
  use 
  of 
  bacteria, 
  as 
  Coccohacillus 
  acridionon, 
  

   d'Herelle, 
  and 
  the 
  locust 
  fungus, 
  Emjnisa 
  gryUi 
  ; 
  these 
  have 
  proved 
  

   of 
  little 
  help 
  in 
  the 
  control 
  of 
  locusts. 
  

  

  During 
  1907, 
  the 
  author 
  tested 
  various 
  other 
  methods, 
  among 
  them 
  

   poisoned 
  bait. 
  This 
  bait 
  consisted 
  of 
  fresh, 
  green 
  grass, 
  finely 
  chopped 
  

   and 
  soaked 
  in 
  a 
  solution 
  of 
  1 
  lb. 
  arsenite 
  of 
  soda 
  and 
  4-11 
  lb. 
  treacle 
  in 
  

   12 
  gallons 
  water. 
  This 
  bait 
  was 
  scattered 
  thinly 
  either 
  in 
  front 
  of 
  the 
  

   swarm 
  while 
  it 
  was 
  moving 
  and 
  feeding 
  or 
  under 
  the 
  shrubs 
  in 
  which 
  

   the 
  hoppers 
  were 
  roosting. 
  The 
  bait 
  was 
  readily 
  devoured 
  when 
  the 
  

   treacle 
  w^as 
  present 
  in 
  the 
  proportion 
  of 
  4 
  lb. 
  to 
  12 
  gallons 
  of 
  water, 
  

   but 
  the 
  hoppers 
  were 
  attracted 
  still 
  more 
  when 
  the 
  proportion 
  of 
  the 
  

   treacle 
  was 
  increased. 
  A 
  swarm 
  fed 
  with 
  poisoned 
  bait 
  at 
  about 
  7 
  a.m. 
  

   would 
  all 
  be 
  dead 
  the 
  following 
  morning. 
  Animals 
  were 
  not 
  allowed 
  

   to 
  graze 
  over 
  the 
  area 
  treated 
  for 
  six 
  days. 
  The 
  use 
  of 
  arsenite 
  of 
  soda 
  

   in 
  the 
  control 
  of 
  locusts 
  saves 
  an 
  enormous 
  amount 
  of 
  labour, 
  and 
  the 
  

   entire 
  swarm 
  is 
  destroyed. 
  The 
  risk 
  to 
  cattle 
  and 
  other 
  grazing 
  

   animals, 
  with 
  ordinary 
  precautions, 
  is 
  infinitesimal. 
  

  

  Kershaw 
  (J. 
  C). 
  Recommendations 
  for 
  dealing 
  with 
  the 
  Froghopper. 
  

  

  — 
  Dept, 
  Agric. 
  Trinidad 
  and 
  Tahago, 
  Sjoecial 
  Circ. 
  no. 
  9, 
  1st 
  Dec. 
  

   1913, 
  10 
  pp. 
  

  

  Under 
  artificial 
  conditions 
  the 
  vermiHon 
  egg-parasite, 
  Oligosita 
  

   giraulti, 
  Cwf., 
  parasitised 
  5 
  to 
  6 
  per 
  cent, 
  of 
  froghopper 
  eggs. 
  After 
  

   careful 
  examination 
  the 
  author 
  concludes 
  that 
  in 
  nature 
  the 
  percentage 
  

   is 
  between 
  5 
  and 
  10 
  per 
  cent, 
  in 
  the 
  most 
  favourable 
  localities, 
  with 
  an 
  

   average 
  below 
  5 
  per 
  cent. 
  This 
  parasite 
  is, 
  therefore, 
  not 
  worth 
  con- 
  

   sideration, 
  and 
  former 
  recommendations 
  for 
  dealing 
  with 
  trash 
  A^ith 
  

   regard 
  to 
  it 
  are 
  cancelled. 
  

  

  The 
  Syrphid 
  fly 
  [Salpingogasfer 
  nigra, 
  Schiner] 
  is 
  the 
  chief 
  check 
  on 
  

   the 
  multiplication 
  of 
  the 
  froghopper 
  in 
  Trinidad. 
  Unfortunately, 
  it 
  

   usually 
  appears 
  in 
  numbers 
  only 
  on 
  the 
  later 
  broods. 
  Its 
  larvae 
  are 
  

   very^ 
  voracious, 
  and 
  in 
  most 
  localities 
  nymphs 
  are 
  scarce 
  after 
  the 
  wet 
  

   season, 
  and 
  the 
  Syrphid 
  larvae 
  will 
  probably 
  either 
  starve 
  or 
  destroy 
  

   one 
  another. 
  Many 
  female 
  froghopper 
  adults 
  escape 
  all 
  enemies, 
  and 
  

   produce 
  the 
  early 
  broods 
  in 
  the 
  ensuing 
  season, 
  when 
  there 
  are 
  but 
  few 
  

   Syrphids 
  about. 
  The 
  author 
  thinks 
  it 
  would 
  be 
  well 
  worth 
  trying 
  to 
  

   breed 
  the 
  Syrphid 
  on 
  through 
  the 
  dry 
  season, 
  in 
  order 
  to 
  have 
  a 
  

   supply 
  ready 
  to 
  distribute 
  on 
  any 
  well-marked 
  early 
  broods 
  of 
  frog- 
  

   hoppers. 
  About 
  300 
  nymphs 
  per 
  day 
  are 
  required 
  to 
  feed 
  100 
  Syrphid 
  

   larvae, 
  but 
  nymphs 
  of 
  Tomaspis 
  jjubescens 
  can 
  be 
  procured 
  in 
  the 
  dry 
  

   season, 
  and 
  a 
  supply 
  of 
  the 
  Syrphid 
  could 
  be 
  kept 
  up 
  in 
  a 
  large 
  cage 
  

   or 
  enclosure, 
  preferably 
  erected 
  over 
  a 
  channel 
  or 
  drain 
  with 
  suitable 
  

   grass 
  already 
  growing 
  there. 
  A 
  light 
  rough 
  construction 
  would 
  serve 
  

   the 
  purpose. 
  The 
  Syrphid 
  will 
  copulate 
  and 
  breed 
  in 
  a 
  large 
  and 
  

   suitable 
  cage. 
  Then 
  a 
  few 
  adult 
  Syrphids 
  and 
  a 
  few 
  maggots 
  could 
  be 
  

   liberated 
  on 
  early 
  froghopper 
  broods, 
  w^herever 
  they 
  occurred 
  in 
  

   numbers. 
  

  

  