ion. The aphis, or plant louse, is
often very numerous on out-door plants, for instance, the rose,
chrysanthemum, cabbage, and fruit trees. They vary in color from green
to dark brown or black. They are treated in the same way as those on
the house plants. Some familiar out-door insects which interfere with
leaf work are the common potato bug, the green cabbage worm, the rose
slug, the elm tree leaf beetle, the canker worm, the tomato worm.
These insects and many others eat the leaves (Fig. 67). They chew and
swallow their food and are called chewing insects. All insects which
chew the leaves of plants can be destroyed by putting poison on their
food. The common poisons used for this purpose are Paris green and
London purple, which contain arsenic, and are used at the rate of one
teaspoonful to a pail of water or one-fourth pound to a barrel of
water. This is sprinkled or sprayed on the leaves of the plants.
Another poison used is white hellebore. This loses its poisoning
qualities when exposed to the air for a time. Therefore it is safer to
use about the flower garden and on plants which are soon to be used as
food or whose fruit is to be used soon, like cabbages and current
bushes. This hellebore is sifted on the plant full strength, or it may
be diluted by mixing one part of hellebore with one or two parts of
flour, plaster, or lime. It is also used in water, putting one ounce
of hellebore in three gallons of water and then spraying it on the
plants. Plants may be sprayed by using a watering pot with a fine rose
or sprinkler, or an old hair-brush or clothes-brush. For large plants
or large numbers of smaller plants spray pumps of various sizes are
used. Sometimes chewing insects on food plants and sucking insects on
all plants are treated by spraying them with soapy solutions or oily
solutions which injure their bodies.

The work of the leaf is also interfered with by diseases which attack
the leaves and cause parts or the whole leaf to turn yellow or brown
or become blistered or filled with holes. The common remedy for most
of these diseases is called the "Bordeaux Mixture." It is prepared as
follows: Dissolve four pounds of blue vitriol (blue stone, or copper
sulphate) in several gallons of water. Then slake four pounds of lime.
Mix the two and add enough water to make a barrelful. The mixture is
then sprayed on the plants.

For more detailed directions for spraying plants and combating insects
and diseases write