30 
The most effective means of destroying this pest is to syringe freely 
with a solution of caustic potash. After the publication of my memo- 
randum on the diseases of lemons, this remedy was tried by Mr. B. 
Dawson, gardener to S. Morrin, Esq., of Remuera, with the best results, 
and will, I am satisfied, prove satisfactory in all cases. It will rarely 
need more than a second application. é 
Washing the affected parts with boiling water is one of the most 
effective remedies that can be adopted, but is scarcely applicable on a 
large scale, and is altogether inapplicable to young shoots during the 
period of active growth. Syringing or washing the tree with a thin 
solution of soft-soap, painting the affected parts with castor-oil contain- 
ing a small quantity of soot, would be found of the greatest value. 
Mr. Maskell has kindly drawn my attention to kerosene made into 
an emulsion with soapsuds, which in America is considered the best 
remedy for scale of all kinds. I have elsewhere stated my reasons for 
preferring castor-oil to kerosene as an insecticide. 
All preparations containing oil must be applied to citraceous plants 
with the greatest care and with alight hand. Castor-oil is an insecticide 
of great value, and, properly applied, is not injurious to vegetable tissue. 
I am, however, confident that, on account of its thorough efficiency, 
cleanliness, and the ease with which it can be applied, weak solutions 
of caustic potash will supersede all other applications recommended 
for the destruction of Icerya, which, owing to its rapid increase, must 
be looked upon as one of the most dangerous enemies which the 
emon-grower has to encounter. 
LEAF-SCALE 
OLIVE-SCALE (Lecanium oleae). 
ORANGE-SCALE (Lecanium hesperidum). 
SANDALWOOD-SCALE (Diaspis santali). 
In addition to the soft-bodied white scale (Icerya purchas?), 
citraceous trees are infested by several scale-insects, more or less 
protected by tests or shields, beneath which they live, and which are 
attached to the epidermis of the plant by their margins, in a similar 
manner to the apple-scale already described. The most common of 
these are the species whose names are given above. Their chief char- 
acteristics maybe briefly stated. 
The orange-scale is found on the twigs and on both surfaces of 
the leaves. It is oval in outline, and about one-fifth of an inch in 
length. The shield is dark-brown and somewhat rugose. It is 
sometimes termed the tortoise-scale, and is found also on holly, 
Portugal laurel, and other trees. ; 
The olive-scale forms minute brown or blackish cushion-like 
bodies on the twigs and leaves. It is very common on citraceous 
trees, but especially on the mandari orange, of which it sometimes 
takes complete possession. Like the precéding, it is naturalised in 
New Zealand, and is commonly called “black scale.” It is also 
found on the plum and other cultivated fruit-trees, as well as on 
several native plants. 
