PEST

NAME
Black Scale
Saissetia oleae

ORDER
Hemiptera

FAMILY
Coccidae

Description of the Pest
Female adults appear as tiny (to 3mm long) dome-shaped dark brown, and have ridges that appear as an "H" pattern on the surface of the scale. They are a 'Soft scale` and produce honey dew.

The crawler stage of the insect is yellow to orange in colour. They are actively moving on the plant until they find suitable feeding spot such as along the vein or stem, where they remain until they die.
Females may lay up to 2000 eggs then die. The eggs are laid beneath the scale, which remains on the plant until the nymphs emerge. The first nymphal stage is termed a "crawler"

Life Cycle
Hemimetabolouslife cycle, i.e. having nymphs and adults as the feeding stages.
There are at least two generations per year in coastal areas of Australia.
One generation per year occurs in inland Australia.

Black scale attended by Ants"H" marking on shell

Distribution of the Pest
Found Australia wide, if a suitable host is present for the scale.

Period of Activity
The pest is active from summer to autumn, particularly in temperate climates with high humidity. It is widespread especially wherever citrus and olives are cultivated.

Damage Caused
Foliage is deformed and yellowed; twigs and branches may die back if the plant is stressed. The pest produces large quantities of honeydew, which attracts ants. The honeydew also encourages growth of sooty mould, this is the main problem as it reduces the ability of the plant to produce sugars and it spoils the plant`s appearance. The mature scales appear in groups along the veins of leaves and on stems.
Sooty Mouldon the leaf

Susceptible Plants
Citrus, stone fruit, apples, olives, passionfruit and many ornamentals and houseplants, including gardenias, geraniums, and jacarandas.

Control

Cultural
Pruning to improve air circulation with the tree.

Biological
A number of parasites attack black scale; the most common are Metaphycus helvolus, Metaphycus bartletti, and Scutellista cyanea. Predators which can be used for biological control include the Orange spotted lady beetle Parapriasus australasiae.
Ants will need to be controlled for the biological agents to be effective. Barriers can suitable for this

Chemical
Heavy infestations may be treated with mild soapy solutions or white oil if it coincides. with the emergence of the crawler stage
Some systemic insecticides are available -Note
It is your responsibility by law to read & follow the directions on the label of any pesticide

Monitoring
Double sided sticky tape can be placed around some of the young stems above where their mothers are. When the crawlers emerge from their mother (who dies after giving birth) some crawlers will adhere to the sticky tape. When numbers are high spray the new growth with soapy water, or an oil based product. This will suffocate the crawlers by blocking their spiracles.
Amendments by B. Sonsie Dip Hort Sc Burnley