Colour - Dull with a thin covering of 'mealy' wax
Body - Up to 10 mm. Oval. Flat. Soft.
Wings - 1 Pair in males, none in females. Wing-span 1 mm
Mouthparts - Stylet. Sucking. Near rear of head.
Antennae - Very small. 3-10 segments.
Eyes - 2. Compound.
Legs -Very small. Feet (Tarsi) have 4 segments.
Head - fused to thorax.
Thorax - 3 segments.
Abdomen - Eight pairs of spiracles on underside. Segments ill defined
Egg - ovoid. Single or in clusters. Egg clusters are often in a cocoon of waxy filaments.
Habits - Males fly but don't feed. First instar mobile. Female sedentary and protects eggs.
Usually 5 stages (instars). Look quite different to the adults.
Biology:Mealy wax helps prevent dehydration of their soft bodies.
Depending on the species they may feed on leaves, fruits, and flowers, seed heads, under bark or on roots.
Pierce cells with mouthparts.
Development is dependent on temperature and 250C with a high relative humidity is optimum for many species.
Life Cycle:Eggs are laid singly or in clusters and hatch to produce nymphs or crawlers. First instar nymph is highly mobile and may also be dispersed by wind. Later instars less mobile. The go through 5 moults to form the adult. For males the last juvenile stage pupates in a silk cocoon and emerges as a winged adult. Males have no mouthparts and do not feed. Mature females are sedentary. There are several generations per year. They tend to live in colonies in dry protected areas and crevices. Peak numbers tend to occur in spring and autumn.
Habitats:Origin and History:
Pseudococcus longispinus damages citrus (Citrophilus mealy bug Pseudococcus calceolariae is a world wide pest that is not present in WA). Planococcus minor damages passionfruit. Pseudococcus affinis is found on roots as well as shoots. Melanococcus albizziae can kill Acacia species. Australicoccus grevilliae damages Grevillea species. Others affect Grapes and Pineapple. Hypogeococcus festerianus was introduced to control Harrisia cactus.
Feeding may cause distorted leaves, weak plants, shiny honeydew and sooty mould on leaves.
Plant damage may be due to removal of water and nutrients or the excretion of toxic salivary products.
There are populations that are resistant to insecticides.
Management and Control:Juvenile Green Lacewings and Damsel Bugs are predators of Mealy Bug and can provide substantial control of all growth stages.
Release parasitic wasps such as Leptomastix dactylopii and Anagyrus fusciventris which can be obtained from www.goodbugs.com.au.
These wasp will lay there eggs in the mealy bugs and the larvae feeds on the internal fluids and usually kills the mealy bug when it pupates.
Predatory ladybirds also provide some control.
Related Species:Aphids, Lerps, various 'bugs' leafhoppers and scales are sometimes confused with Mealy Bugs.
CSIRO. The Insects of Australia. Melbourne University Press. (1991) p459-461, 463f30.25.
Goode, J. Insects of Australia. Angus and Robertson. p61.
Hoffman & Botha (2006) Garden Note #206, DAFWA.
Jones, D. & Elliot, R. Pests Diseases and Ailments of Australian Plants. Lothian Publishing Co. p67.
Acknowledgments:Collated by HerbiGuide. Phone 08 98444064 or www.herbiguide.com.au for more information.