740 
THE 
TROPICAL  AGRICULTURIST. 
[May  I,  1897. 
or  March  moth,  which  lays  its  eggs  in  bands  embedded 
in  down  on  the  twigs,  is  (or  very  likely  is)  also 
present. 
These  various  moths,  including  besides  what  may 
be  called  those  of  common  habits,  such,  that  is,  as 
moths  which  come  on  the  wing  to  the  tree,  and  of 
which  the  eateipiUars,  after  feeding,  spin  up  on  the 
bark,  or  in  any  convenient  shelter,  may  be  counteracted 
in  some  degree  by  measures  based  on  knowledge  of 
their  habits.  The  Webs  of  those  that  make  nests  may 
be  cut  oil  and  destroyed  with  the  caterpillars,  or  (in 
the  case  of  tho  small  ermine  moth)  the  chrysalids, 
within  them.  Cocoons  covered  with  eggs,  as  in  the 
case  of  the  common  vapoiirer  moth,  may  be  searched 
for  and  destroyed;  and,  similarly,  the  rings  of  eggs 
of  the  March  moth  aud  of  the  lackey  moth,  which 
resemble  them  in  being  laid  in  a band  on  twigs, 
may  be  got  rid  of  in  some  degree  by  careful  search, 
and  pruning  off  the  infested  twigs  where  they  can 
be  reached.  But  for  tho  most  part  these  and  various 
other  means  of  prevention  or  remedy  have  to  be  applied, 
not  as  broad  measures  of  treatment,  but  as  special 
measures  for  each  special  attack,  involving  necessarily 
special  outlay.  For  these  reasons,  that  is,  the  pressing 
need  which  has  long  been  felt  of  having  some  kind 
of  application  at  hand  which  is  cheap  and  sure  in 
its  action,  and  which  can  I e brought  to  bear  at  once, 
when  required,  on  any  or  all  sorts  of  moth-caterpillars 
together  (whate'  or  their  various  natures  or  previous 
histories  may  have  been),  and  will  kill  the  whole 
collection  of  ravaging  hordes  at  once,  without  dam- 
aging the  leafage,  the  experiments  have  been  made, 
which  have  resulted,  in  some  of  our  fruit-growing 
districts,  in  the  successful  introduction  of  the  method 
of  spraying  caterpillar-infested  leafage  with  Paris- 
green,  which  has  long  been  found  serviceabe  in  the 
United  States  and  Canada. 
Another  very  important  division  (taken  agricul- 
turally) is  that  of  the  surface  caterpillars,  so-called 
from  their  injurious  operations  being  for  the  most 
part  carried  on  near  the  surface  of  the  ground. 
The  family  of  moths  to  which  these  belong  is 
termed  Noctuidee,  from  the  circumstance  of  many  of 
them  flying  chiefly  at  night  or  in  the  dusk.  The 
heart  and  dark  moth,  the  caterpillar  of  which  is 
almost  as  often  found  at  turnip  bulbs  as  that  of  the 
turnip  m jth  ; cabbage  moth,  the  great  yellow  under- 
wing,  and  some  other  kinds,  the  caterpillars  of  which 
more  or  less  frequent  the  surface  of  the  ground,  do 
infinite  harm,  both  in  field  and  garden.  In  some 
oases,  like  the  turnip  moth  caterpill.irs,  they  feed  at, 
or  bellow,  the  ground-level  on  almost  every  common 
root  crop,  or  corn  crop,  they  can  reach  ; aud  when 
the  weather  is  too  severe  in  winter  for  them  to 
continue  feeding  in  the  turnip  bulbs,  they  simply  go 
down  deeper  for  a time,  and,  after  coming  up  again 
to  feed,  turn  to  chi-ysalids  in  the  ground  in  the 
following  spring  or  early  summer.  Others,  like  the 
caterpillars  of  the  cabbage  moth,  feed  in  the  hearted 
cabbage,  aud  turn  to  chrysalids  in,  or  on,  the  surface 
of  the  ground  before  winter.  But,  whatever  slight 
difference  there  may  be  in  the  habits  of  these  various 
kinds  of  thick  fleshy  caterpillars,  about  an  inch  and 
a half  long,  which  we  only  too  often  find  either  at 
the  roots  or  on  the  leaves  of  the  cabbage  and  turnip, 
this  special  point  of  their  usually  passing  the  winter 
under  ground  puts  them  very  much  in  our  power. 
Before  the  caterpillar  turns  to  the  chrysalis,  it  makes 
a cell  in  the  earth,  in  which  it  is  protected  from 
wet  aud  sudden  changes  of  temperature,  or  it  seeks 
or  prepares  a safe  resting-place  for  its  change,  or 
for  a time;  and  so  long  as  tho  caterpillars  are  thus 
protected  no  amount  of  cold  to  which  they  are  here 
exposed  will,  as  far  as  we  know,  do  them  the  least 
harm.  But  if  they  are  thrown  nut  of  the.se  shelters 
to  the  influence  of  drying  winds  or  hot  sunshine,  or 
to  lie  soddening  helplessly  on  tho  surface  in  moist  or 
muddy  ground,  or  to  being  frozen  in  these  states, 
then  their  constitution  wilt  not  bear  it. 
If  tho  caterpillars  are  turned  uj)  too  soon,  that 
is  either  before  they  are  torpid,  or  before  they  have 
changed  to  tho  chrysalis,  they  will  simply  go  down 
again.  If  the  soil  is  turned  up  when  they  are  gone 
down  very  deep,  they  will  not  be  the  worse  for  what 
has  been  done  above  them.  Each  worker  must  look 
a little  for  himself,  for  dates  and  habits  differ  with 
climate  and  other  things  ; but  a little  careful  observation 
made  by  turning  over  the  earth,  so  as  to  see  where 
the  creatures  are,  will  be  well  repaid.  They  are  quite 
large  enough  to  be  easily  seen,  if  they  are  in  numbers 
to  need  attention.  This  principle  may  be  worked 
both  in  winter  and  summer — with  caterpillars  that 
turn  to  chrysalids  under  ground  or  in  cocoons  above 
ground,  and  with  those  that  frequent  leafage  of  trees 
or  roots  of  grass,  as  well  as  those  we  have  spoken 
of. 
The  common  cabbage  and  turnip  surface  cater- 
pillars will  be  found  thus  (or  when  time  has  elapsed 
for  their  change  to  take  place),  in  chrysalis  state, 
on  or  in  the  ground  near  where  they  fed. 
The  beet  and  mangold  moth  (silver  Y moth)  caterpillar 
spins  a cocoon  on,  or  not  very  far  from,  the  plants 
it  infested ; and  in  all  these  cases,  and  scores  of 
others,  much  good  may  be  done  by  turning  up  the 
chrysalids,  destroying  tlie  weeds  they  harbour  in,  and 
using  all  other  methods  of  treatment,  which  a 
moment’s  thought  will  suggest,  to  destroy  the  pests. 
Clearing  all  weeds  that  attract  the  moths  is  one 
method  of  preventing  increase.  The  constantly  in- 
creasing amount  of  insect  attack  is  in  part  because 
of  the  constantly  wider  spread  of  cultivated  land. 
There  is  a much  greater  amount  of  special  crops, 
such  as  special  insects  feed  on  ; and  instead  of  there 
being,  as  in  wild  districts,  perhaps,  one  plant  in  a 
hundred  that  may  suit  the  caterpillar,  there  are 
districts  all  through  the  country  where  nine-tenths 
of  the  growth  are  its  chosen  food.  If,  therefore,  in 
addition  to  the  crop  food,  we  let  weed  food  collect 
in  our  borders,  we  add  moat  needlessly  to  our  troubles  ; 
and  by  clearing  and  burning  these  patches  round 
garden  and  fields  we  may  do  a deal  of  good. 
When  attack  is  bad,  the  chief  thing  to  trust  to 
is  fertilising  dressing ; but  sometimes  dressings  of 
gas-lime  on  the  land,  and  on  the  plants,  will  check 
attack  to  a serviceable  extent.  This  has  been  found 
useful  in  the  attack  of  caterpillar  to  hearted  cabbage 
in  the  autumn.  The  gas-lime  falls  down  among  the 
leaves,  and  thus  fills  the  parts  where  the  caterpillars 
shelter  by  day,  with  what,  to  a certain  extent,  keeps 
them  out,  aud  is  not  pleasing  to  them. 
It  was  formerly  difficult  to  apply  this  knowledge 
practically ; but  now,  looking  at  the  variety  of  im- 
plements which  have  been  recently  introduced  into 
this  country,  suitable  for  spraying  or  washing  either 
orchard  tree  leafage  or  that  of  field  crops,  there  would 
be  no  difficulty  in  experimenting,  at  least  on  orchard 
foliage,  as  to  the  effects  of  cold  water  in  clearing  off 
caterpillar  presence. 
The  treatment  for  prevention  of  surface  caterpillars 
may  be  shortly  described  thus : — Turn  them  up  by 
cultivation  where  land  is  known  to  have  been  infested; 
and  where  catch-cropping  is  practised  let  the  field 
be  cleared  of  all  food  at  least  a fortnight  before  a 
new  crop  is  put  in  ; keep  up  the  strength  of  the  crop, 
but  use  remedies  if  you  can — if  they  will  be  sure  to 
destroy  the  grubs. 
In  a very  large  number  of  attacks,  it  is  the  worst 
possible  practice  to  try  to  work  directly  on  the  grubs ; 
you  must  counteract  their  mischief,  rather  than  try 
to  get  (literally)  hold  of  them ; but  with  the  large 
moth  grubs,  which  are  often  one,  instead  of  a score 
of  hundreds,  to  a plant,  the  case  is  different. 
For  the  same  reason,  birds  help  us  much  with 
some  kinds  of  moth  caterpillars.  They  can  bore  down, 
and  draw  out  tliese  large  grubs,  without  the  broadcast 
destruction  which  often  follows  on  their  services  in 
searching  for  -wireworm. 
The  crow,  raven,  jackdaw,  rook,  and  partridge,  are 
all  said  to  be  of  use  in  clearing  away  the  cater- 
pillars of  the  turnip  moth  ; and  in  the  case  of  some 
of  the  swarms  of  small  caterpillars  which  attack  forest 
trees,  especially  the  small  green  oak-leaf  roller  (Tortrix 
viridnnn),  the  flocks  of  birds  which  collect  when  great 
attack  is  going  forward  are  our  only  helpers. 
