Supplement  tj 
March  10,  19C4 
2U 
JOURNAL  OF  HOUTTCULTURE  AND  COTTA  :L  GaBUENER. 
INSECTICIDES. 
insecticide  is  any  composition  prepared  from  ingredients 
desti'iictive  to  insect  life.  I’o  he  effective  and  uvail- 
able  tor  use  on  plants,  it  must  he  fatal  to  insects  with¬ 
out  in  any  way  iniuring  the  liost.  I'liis  is  really  the 
ci-iix  of  the  whole  matter,  for  the  difficulty  is  not  compound¬ 
ing  an  insecticide  that  will  destroy  insect  pests,  vitliout  at  the 
same  time  causing  injury  to  the  jilants  inlested  hy  them.  A 
brief  digest,  therefore,  of  .some  artich's  in  general  use  as 
insecticides  ^A-ill  ho  interesting,  ■suggestive,  and  useful. 
Arsenic, 
'rids  is  known  to  chemists  as  ai'senioiis  acid,  or  vhite  oxide 
of  arsenic.  In  its  simple  form  it  must  ho  regarded  as  a  very 
unsafe  insecticide,  not  oidy  as  regai’ds  injury  to  the  jrlant,  l)ut 
also  from  its  colour  allorving  it  to  he  ndstaken  for  other  sub¬ 
stances,  and  its  fatal  ('ffects  on  human  and  do.mesticat('d  animal 
life.  Its  use,  how('ver,  in  its  various  compounds,  known  as 
aixmites,  enables  the  cultivator  to  combat  .successfidly  some 
of  the  Avorst  enemies  of  his  crops,  such  as  cater])illars  and  adult 
insects  biting  and  devouring  portions  of  the  planks.  Such 
insects  must  he  poisoned,  and  one  of  the  most  virulent  pois;ons 
is  ars('nic.  'this,  as  white  arsenic,  is  only  used  for  destroying 
ants,  vhen  formed  into  a  syrup  with  sugar  as  follows:  — 
Ant  Poison.  — Place  loz  of  ordinaiy  ai-.senic  in  an  old  iron 
pot  with  a  quart  of  watei',  and  boil  until  reduced  to  a  pint,  or 
a  little  more,  of  li(|uid,  then  add  ,^11)  Demerara  or  cane  sugar, 
and  stir  well.  This  syrup  or  mixture  can  ho  dropped  on  hits  of 
glass  or  glazed  earthenware,  and  placed  about  the  runs  and 
around  the  nests,  or  placed  in  .saucers  in  the  ants’  haunts. 
This  must  he  used  with  the  utmost  caution. 
Arsenites. 
Ar.senites  are  compounds  of  arsenic  in  which  arsenious  acid 
unites  with  a  metallic  base.  The  principal  arsenites  used  in 
destroying  insects  are  Paris  green  and  London  purple. 
Pahis  gueen,  also  known  as  “  emerahl  green,”  is  an 
aceto-arsenite  of  copper,  a  poisonous  compound,  verdigris. 
copper,  and  ar.senic.  An  average  analysi.s  shows:  Arsenic 
47.68,  copper  oxide  27.47,  sulphuric  acid  7.1G,  moisture  1.3o, 
insoluble  residue  2.34  per  cent.  It  is  applied  either  in  a  wet 
or  dry  condition.  For  making  a  dry  mixture,  commonly  used 
in  the  United  States,  hut  not  in  this  country  to  any  appreciable 
extent,  gypsum,  flour,  air-slaked  lime,  road  dust,  or  sifted 
wood  ashes  may  he  used.  The  strongest  mixture  recommended 
in  the  United  States  is  one  part  of  Paris  green  to  fifty  paits 
of  the  diluent,  hut  if  the  mixing  is  very  thoroughly  done,  one 
part  to  100,  or  even  200,  is  sufficient.  Thus  the  strength  of 
the  mixture  required  depends  upon  the  plants  and  imsects  to 
which  it  is  to  ho  applied,  points  upon  which  cultivators  must 
exerci.se  di.scriminative  .judgment. 
In  this  country  Paris  green  is  almost  always  used  in  the 
wet  state;  indeed,  the  article  is  .so  fine  and  dangerous  to  handle 
in  the  dry  .state  that  it  is  advisable  to  procure  it  in  the  form 
of  paste,  Blundell’s  being  the  he.st  make.  It  is  practically 
insoluble  in  water,  though  some  of  the  ar.senic  may  be  in  a 
soluble  form,  therefore  it  is  always  important  to  add  twice 
as  much  freshly  burned  and  slaked  lime  as  of  Paris  green  in 
order  to  prevent  injury  to  the  foliage  of  plants  or  trees.  The 
mixture,  loz  Paris  green  and  2oz  slaked  lime  to  twehre  gallons 
of  water,  must  he  kept  in  a  constant  state  of  agitation,  else 
the  poison  will  .settle,  and  the  liquid  from  the  bottom  of  tho 
vi's.sel  Avill  he  so  strong  as  to  do  serious  damage,  while  that  from 
the  top  will  he  useless.  This  is  very  important,  therefore  never 
charge  the  spraying  vessel — a  knapsack — without  fii’.st 
thoroughly  stirring  and  agitating  the  liquid  in  the  preparing 
ves.sel. 
The  strength  of  the  mixture  should  not  exceed  the  pro¬ 
portions  ((uoti'd,  this  being  safe  to  use  on  Plum  trees,  hut 
Apple  and  Pear  trees  are  more  tender  in  their  young  foliage, 
hence  loz  Paris  green,  2oz  slaked  lime,  and  twmity  gallons  of 
water  is  an  advisable  and  effective  mixture.  For  caterpillars 
generally,  and  iiarticularly  tho.se  of  tho  Winter  Moth,  spray 
just  hefore  the  bloom  buds  open;  repeat  just  after  tlio  bloom 
has  .set,  and  if  caterpillars  are  to  he  seen  afterwards,  spray  at 
intervals  during  the  sea.son.  Spraying  with  Paris  green,  or 
arsenites,  should  not  he  practised  on  trees  in  full  bloom,  nor 
within  .six  weeks  of  the  time  of  picking  fruit.  In  all  cases 
the  liquid  should  he  applied  with  force  in  a  very  fine  spray,  just 
Kelway’s  New  Tree  Pfconies. 
Kdici'j  il-  Son. 
