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San
Jose Scale
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Information on this page is derived from public domain documents published
by the federal government of canada, the provincial government of British
Columbia and information contributed on electronic discussion groups.
Please bear in mind that any pesticides mentioned in these pages may
no longer be recommended or registered for the indicated use — check
with your local pesticide officer or regional agrologist for current info
(you can use the provincial directory
on the internet to search for those job titles or call Enquiry
bc at 1 800 663-7867 for assistance). It is recommended that you use
a search engine using the common name and/or scientific name of the organism(s)
below, together with the name of your province, to find biology and management
information relevant to your local conditions.
If
you choose to use chemical controls remember to
always follow pesticide label instructions!
insects
of economic importance in Canada and British Columbia
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family: diaspididae
species: quadraspidiotus perniciosus
common names: san jose scale
hosts:
notes: Gluthion will kill the natural enemy fauna
 
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Agriculture and Agri-Food Canada Insect Identification
Sheet No. 38 March 1981
San Jose Scale
Quadraspidiotus
pemiciosus (Comstock)
The San Jose scale is a major pest of fruit trees in British
Columbia and Nova Scotia, and in southern Ontario and Quebec.
It is also found on many bush fruits and shrubs, and on some
shade and forest trees.
Injury:
A heavily
infested tree will lack vigor and its foliage will be thin
and yellow-speckled. If the infestation is not checked,
the tree will die. San Jose scales appear as small, disk-shaped
specks on the bark; if a hand lens is
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used,
a raised nipple-shaped spot can be seen at the center of
each disk. Often the bark
around the scales is reddened. In appearance, a heavily infested
tree looks as though it had been sprinkled with wood ashes
when wet. The fruit may also be attacked, usually near the
blossom and stem ends. On the fruit, the insects appear as
gray patches, each surrounded by an inflamed red area.
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Life
History:
The insect overwinters on the bark in the first nymphal, or
sooty black, stage. With the resumption of the sap flow in
the spring, the insect begins to grow and is usually fully
grown by the time the trees come into bloom. Females are covered
by scales that are nearly round and about 2 mm across; the
waxy covering of the males is oval-shaped and about 1 mm across.
The females remain under their scales throughout their lives.
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In late May or early June, the males begin to emerge and mate
with the females which give birth to living young. These usually
appear in the latter part of June and are most numerous on the
upper branches. Resembling very small yellow mites or lice, the
young insects move about on the bark or fruit for about a day after
birth and then begin to feed on the sap. In molting, the growing
insects lose their legs and antennae, but remain attached to the
feeding surface by their sucking mouth parts. As each insect continues
to grow, a waxy secretion is given off by its body and this hardens
into the protective scale under which it lives. In southern Ontario,
there may be two or three generations a year. Dry, hot seasons
favor the increase of this insect.
Control:
Spray with
a superior oil (70 sec. viscosity) in the spring while the trees
are still dormant. Do not spray during the bloom period. A post-bloom
spray consisting of a contact residual insecticide should be
used to control the pest in its crawling stage. For information
on the control of this insect consult
your provincial Department of Agriculture.
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