7i 
by white-washing with lime and water. This requires renewal once 
in three weeks. Special preparations are sold for applying to trees. 
In the form greasy mixtures, rosin and castor oil, whale oil-soap 
and washing soda, soft soap and carbolic acid are recommended 
for this purpose, but these must not be allowed to remain long on 
the trees. After 2 to 3 months, at most, they should be washed 
off. Trunks of valuable trees can be protected by tying tarred 
paper, or newspapers, around them, or by fixing wire netting one 
inch away from the bark closed at the top and bottom. Lime, 
ashes and soot can often be employed very usefully in gardens, 
especially against snails and slugs. 
Stored crops are very liable to the attacks of insects. Grain may 
be freed from,, weevils by exposing it for 24 hours in an airtight 
receptacle, to the fumes of carbon bisulphide at the rate of I 
teaspoonful (1 drachm) per cubic foot of space. This will kill 
every insect within 24 hours and will not damage the grain. Car- 
bon bisulphide is obtainable in cans from 7 lbs. upwards at about 
§d. per lb. in England or the United States. Benzene may. be 
used in the same way, taking rather more per cubic foot as it is 
less powerful. As both these substances are very inflammable, 
care must be exercised in using them. Cockroaches can be des- 
troyed by mixing equal parts of molasses, or chocolate, and boracic 
acid, and spreading this on small pieces of tin or cardboard, which 
are placed in cupboards or under furniture. The mixture is not 
poisonous to dogs and other domestic animals, but will destroy the 
cockroaches. Books in the tropics should always be lightly painted 
over with the following mixture to preserve them from cockroa- 
ches : — 
1 oz. Corrosive Sublimate. 
1 oz. Carbolic acid. 
2 pints Methylated or Rum spirits. 
The paste use for binding books and similar work should be 
poisoned by adding half an ounce of copper sulphate (blue stone) 
to every pound of paste. 
Wicker and other furniture attacked by small beetles should be 
thoroughly painted with kerosene oil and then placed in the sun 
for a few days. Woollen good-, clothes, etc., can be preserved 
from the clothes' moth bv the use of naphthalene, but better by 
being thoroughly sunned for a whole day once every two months. 
Useful Insects. 
Insect pests, like other organisms, have enemies that prey on 
them dearly, these are of value and deserve to be encouraged. A 
common pest destroyer is a green fly about an inch long with large 
transparent wings, and beautiful golden eyes, which emits a very 
unpleasant smell. Its eggs are found on the bark or leaves of 
plants infested with plant-lice, and are easily recognizable, resemb- 
ling small white grains on a slender stalk. The grub is a very 
voracious animal and devours large numbers of plant lice, etc. 
Other useful insects are the small round beetles known as ladybirds. 
Their grubs are usually coloured black and yellow, and are very 
