PEST
 
   NAME
     Scale Insect
     Various Scale Species
 
   ORDER
     Hemiptera

Description of the Pest
Generally scales are soft bodied insects that have a hard (armoured) or soft covering to hide under. They have piercing and sucking mouth parts that are attached to the host, feed off sap and soft scales commonly producing sweet honeydew, which in turn attracts sooty mould and ants. 
The adult female has a circular or oval covering depending on the species and is up to 8mm across. The first stage (crawlers) hatch and wander around the leaf surface until finding a suitable place to suck sap, normally in colonies and the smaller male is relatively inconspicuous.

   Hard Scale	   Soft Scale, attending Ants

Cactus Scale (Diaspis echinocacti) has a circular greyish female and a narrow white male scale and is commonly found on house plants.

Chain Scales (Pulvinaria species) adult females are obvious with large group of eggs that are white or cottony-like, and the tiny young light green scales are flat and oval-shaped up to 2mm long. The legged nymphs are normally arranged from head to tail along the mid rib of the leaf, and may move to a new position to feed. They excrete honeydew and attract sooty mould and are found on Acacia and Acronychia species.

  Chinese Wax Scale 

Chinese Wax Scale (Ceroplastes sinensis) is a domed wax scale that has dark spots around its margin and immature scales form waxy material around there margins.

   Fern Scale on Aspidistra elatior

Fern Scale or Coconut Scale (Pinnaspis aspidistrae) appears as flecks up to 0.15mm long with a white covering over the male congregating on the underside of the fronds on the axils and among the sporangia causing them to turn yellow. Many species of fern are susceptible to infestation.

		  Flat Brown Scale

Flat Brown Scale (Eucalymnatus tessellates) are light brown up to 0.5mm long, flat and closely attached both sides of the leaf and causing yellowing of the foliage.

Juniper Scale (Diaspis carueli) is tiny and circular, white maturing to grey-black and as it feeds the needles turn yellow and die.

Oleander Scale (Aspidiotus hederae) is a pale yellow circular scale up to 3mm across and is found in dense colonies on the stem or leaves.

Tea-tree Scale (Eriococcus orariensis) are a creamy blue colour normally packed along the branches and are plump and rounded to 4mm across.

		 Wattle Tick Scale

Tick or Wattle Scale (Cryptes baccatus) adult is domed, blue-slate colour with a leathery covering up to 10mm long. All stages of growth are found in groups of over forty, packed along the stems and normally tended by ants as they produce large amounts of honeydew. A serious pest of Acacia species found inland or coastal from temperate to sub tropical climates and commonly accompanied by Sooty Mould.
 
Toxic Scale (Hemiberlesia lataniae) is a tiny flat rounded scale up to 0.15mm long and is white to pale pink. It is normally found in colonies on the small branches and twigs of shrubs. It injects a toxic substance into the host as it sucks sap causing the death of the branch. 

Wattle Scale (Pseudococcus albizziae) is soft, plump and secrets cotton-like threads. It is not a true scale insect and is simular to mealy bugs. It is reddish-brown up to 0.4mm long and secrets large amounts of honeydew as it sucks sap in colonies along the branches.

Life Cycle
These insects have a Hemimetabolous life cycle, ie. When the immature nymphs resemble the adults.

Appearance of the Pest
All parts of the plant above the soil may be attacked, but normally the stems and leaves and scale tends to favour well-lit positions.

Period of Activity
The nymphs and females are active for most of the year, in warm climates. Once they selected a position they attach and don’t move. Normally the winged or wingless males are mobile and only soft scales produce honeydew. 

Susceptible Plants
There is a wide range of susceptible plants including citrus, willows, holly, and many ornamentals, such as roses or Paeonia species. It also attacks indoor or glasshouse plants and Australian native plants such as wattles, hakeas, grevilleas and eucalyptus. 

Acacia species are attacked by the Tick or Wattle Scale, which infest twigs and small branches and heavy infestations will kill the host plant.

Acer species are attacked by the Cotton Maple Scale (Pulvinaria innumerabilia) which prefers Acer saccharinum. Nymphs first attack the leaves and the brown adult scale is covered in a woolly mass up to 14mm across, normally found on the underside of the stems and twigs.

Acmena smithii, Melaleuca, Syzygium and Pittosporum species are attacked by the Chinese Wax Scale.

Aesculus species are attacked by several scale insects including the Walnut Scale (Aspidiotus juglans-regiae) which is saucer-shaped and attacks the main trunks.

Agave species are susceptible to several types of scale including (Aspidiotus nerii), (Aonidiella aurantii) and (Pinnaspis strachani), but generally do not require control.

  Asplenium australasicum

Asplenium australasicum is susceptible to Coconut Scale or Fern Scale (Pinnaspis aspidistrae). It is normally found on the under side of the fronds. Small infestations cause little damage.

Bougainvillea species may be attacked by the soft scale (Coccus hesperidum) outdoors or under glass.

Calluna and Vaccinium  species are attacked by the Oyster Shell Scale (Lepidosaphes ulmi). 

Camellia species may be attacked by the Florida Red Scale (Chrysomphalus aonidum), which is small, circular and black and is found firmly attached to the underside of the leaf along the veins. On inspection after removing the scale the insect has a pale yellow body. Camellias are also attacked by a large variety of scale insects including Tea Scale and Camellia Scale.

Carpinus species may be attacked by the scale (Phenacoccus acericola). It is found on the underside of the leaves forming a white cotton-like clump along the veins.

Casuarina and Allocasuarina species may be attacked by the Casuarina Scale (Frenchia casuarinae), a black hard scale that is upright to 4mm with a pinkish body. During attachment the surrounding tissue swells up and in time can, form galls. This weakens the wood and in severe infestations may kill the tree.

Cotoneaster species are attacked by up to four species of scale including the Oyster Shell Scale (Lepidosaphes ulmi).

Cupressus species are attacked by Bark Scale (Ehrhornia cupressi) is pink and covered in white wax. Heavy infestations cause the leaves to turn yellow or reddish.

   Flat Brown Scale on Cycas revoluta

Cycads, palms and some species of Callistemon are attacked by the Flat Brown Scale. 

Erica species are attacked by several species of scale including, Greedy, Oleander and Oystershell scale.

Jasminum species can be infested with up to twelve types of scale.

Juniperus x media and other conifer species are attacked by the Juniper Scale.

Leptospermum species are attacked by the Tea-tree Scale which produces ample honey dew that promotes sooty mould. 

Palm and Fern species are susceptible to attack by the Coconut Scale or Fern Scale (Pinnaspis aspidistrae) which infests the underside of the leaves. They are also hosts for many other scale species such as red, cottony cushion and tea scale.

Pinus species are attacked by several species of scale including the Pine Tortoise Scale (Toumeyella numismaticum) and the Red Pine Scale (Matsucoccus resinosae).

Sorbus aucuparia is attacked by a five species of scale insect, including Black Cottony Maple, San Jose and Scurfy. Generally they suck on the sap of the new growth and leaves.

Strelitzia species are attacked by the Greedy Scale (Aspidiotus camelliae).

Damage Caused
Leaves become yellow and are shed prematurely and there may be twig or stem die-back. When the infestation occurs on fruit, the fruit is small and its skin becomes pitted and cracked. Small trees and saplings that are heavily infested may be seriously damaged or die. Sooty mould can cover fruit or leaves causing a secondary problem. 

Cactus Scale can completely cover the host cactus sucking sap and causing it to die.

Cultural Control
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 
Natural predators such as parasitic wasps may reduce numbers of active nymphs; parasitic wasps are bred commercially in some areas for this purpose. It should be noted, however, that wasps would avoid dusty conditions. 
Other predators that assist in control are assassin bugs, ladybirds, lacewings, hover flies and scale eating caterpillars. A variety of birds also attack scales. 
The control of ants that transport aphid from one host to another also reduces infestation and can be carried out by applying at least three greased bandages 5mm apart around the stem or trunk of the plant. 

Chemical Control
Spray the entire plant with dilute white oil solution; a follow-up spray may be required after four weeks, for heavy infestations. Spraying of chemicals will also kill of natural predators and in some cases the secondary scale infestation is more prolific especially when using copper based chemicals.
Some chemical controls, such as methidathion, are available - please seek advice from your local nursery as to the suitable product for your area.
Note
Always read the label for registration details and direction of use prior to application of any chemicals.