Garden Pests in New Zealand: A Popular Manual for Practical Gardeners, Farmers and Schools — John Stuart Mill — John Shaqi
Garden Pests in New Zealand: A Popular Manual for Practical Gardeners, Farmers and Schools
John Stuart Mill · en
This scale is a circular one, with a central pimple-like prominence, as
in the case of the San José, but is flatter, about half as large again,
and is of a characteristic reddish colour. The damage done to citrus
trees by this insect is of a serious nature, as the entire tree or part
of it may be killed in severe infestations. A characteristic feature
of this species is that no honey-dew is secreted, and hence there is a
total absence of sooty mould on infested trees.
Like the San José scale, the red scale is viviparous, and over-winters
as partially mature adults, completing development in early spring,
when the young insects make their appearance. An average of about 55
young is produced by each female, and development to maturity takes
from two or two and a-half months; about one month later young are
produced, and their production continues over a period of one or two
months; climatic conditions, however, have a direct influence on
development.
An important natural enemy is the steel blue ladybird (_Orcus
chalybæus_), imported from Australia; but the most efficient control is
cyanide fumigation, or spraying with red oil or lime-sulphur.
THE BLACK SCALE(_Chrysomphalus rossi_).--Foliage of palms, oleander
and citrus is often infested by this reddish-black to black circular
scale (Fig. 7, 3); it is almost flat, with a central whitish spot, and
measures up to one-tenth of an inch in diameter; when many individuals
are crowded together, their outline becomes irregular. This species is
not especially injurious, though common.
OLEANDER SCALE(_Aspidiotus hederæ_).--This cosmopolitan insect occurs
on orchids, oleander, ivy, camellia, palms, citrus, coprosma, and
karaka, infesting stems, leaves and fruit. In the case of citrus, this
insect delays colouring of the fruit, which becomes blotched with
yellow or green. The insect may be so numerous, that it completely
covers the whole plant, giving to the latter a white appearance; this
is due to the preponderance of white male scales, the female being
slightly yellow, with a purplish tint.
The female scale is almost circular (Fig. 7, 7), having a diameter of
from one-twenty-fifth of an inch to two-twenty-fifths of an inch, and
is rather flat; the male is more oval and of the same size, and in both
cases there is a central orange-yellow spot. The eggs are comparatively
large, and hatch soon after being deposited. The insect reaches
maturity in from four to six weeks.
GREEDY SCALE(_Aspidiotus rapax_).--This European insect is now
widespread, and in New Zealand is common on apple, pear, quince, and
wattle; it has a wide range of hosts. The adult female scale is convex
and of a general grey colour, though sometimes yellowish. The winter is
passed in all stages of development.