PEST
 
   NAME
     San Jose Scale
     Quadraspidiotus perniciosus
 
   ORDER
     Hemiptera
 
   FAMILY
     Diaspididae

Description of the Pest
An armoured scale (sometimes known as hard scale). Adult females are yellow, soft bodies and the size of a pinhead, with a 2mm grey-brown, conical covering scale; males are smaller, ovoid with the raised section towards one end of the scale. This is a major pest in some areas and is difficult to detect, as they are small, resemble the twigs that they are on.

Appearance and Distribution of the Pest
Known throughout the world. It is quarantined in South Australia, where this scale is not seen.

Life Cycle
This insect has a Hemimetabolous life cycle, ie. When the immature nymphs resemble the adults.
There is a gradual metamorphosis, with several generations appearing in each year; the life cycle is about six weeks. Nymphs are six-legged and mobile, until they settle and begin to feed on the sap. Adult males emerge from their scale coverings as minute winged insects.

Period of Activity
Most activity occurs during the warmer months.

Damage Caused
All above-ground parts of the plant may be attacked. Scales may overlap, covering the bark of the plant; feeding scales inject a toxic substance, which may kill twigs and limbs in heavy infestations. Because it is a proclaimed pest, control is required by law: scale must be removed from all infested plants in an orchard, and export of infested fruit is prohibited.

Susceptible Plants
Deciduous fruit trees, especially apples, pears, stonefruit. Ornamental trees and shrubs such as Paeonia and Cotoneasters, Thuja species are also attacked.

Cultural Control
Sticky traps may be used to control crawlers; traps should be changed weekly. Dead or damaged parts of the plant should be removed and destroyed including fallen fruit. Small infestations may be removed by hand or squashed on the stems. Healthy plants are less susceptible to attack, so maintain vigour of the plant and avoid using high-nitrogen fertiliser that produces excessive soft young growth.
When pruning susceptible plants paint the cuts with antifungal sealant paint as scale insects are attracted to the sweet smell of the sap. This will reduce the infection rate of the plant. 

Biological Control
Native ladybeetles, other predatory beetles and scale-eating caterpillars do not reduce numbers significantly.

Chemical Control
White oil and other oil sprays smother the insects, but do not destroy the eggs. Methidathion may be successfully used commercially.
Note
Always read the label for registration details and direction of use prior to application of any chemicals.