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Green Coffee Scale in Longan

Geoff Waite & Rod Elder, Department of Primary Industries and Fisheries.


Longan: Green coffee scale in longan

Description

Adult

The adult female of green coffee scale is oval to elongate in shape, with a flattened profile. It is pale yellow-green in colour, and 3-4 mm long. The roughly U-shaped gut is visible through the partially transparent top of the scale as a line of black spots. At the anterior (head) end there are distinctive black eye spots. The scales have short antennae and well-developed legs, and unlike most scales, can move slowly around the host plant. These features can be used to distinguish the scale from other soft scales such as soft brown scale.

Immature stages

Eggs are not visible as they hatch inside the female body or immediately after they are laid. I mmature scales are similar in appearance to the adult female, but smaller.

Life history

The females reproduce without mating. The life cycle takes 6-9 weeks and there may be 3-4 generations per year.

Distribution

Green coffee scale occurs from just south of Brisbane to north of Mareeba.

Host range

Longans, coffee, citrus and a wide range of other hosts, including ornamentals such as gardenia and ixora.

Management

Importance

Major and sporadic; potentially serious in coastal areas and its occurrence is increasing in sub-coastal areas.

Damage

This insect damages longans by infesting leaves, twigs and fruit from which it suckis sap.  Secretions of sugary excreta provides a medium on which sooty moulds thrive.

Action level

Monitor once or twice together with other soft scales, from mid-October to mid-November. Sample 25 leaves from each of 20 randomly selected trees per 1 to 5 ha block. Apply a spray if 10 or more leaves are infested with 1 or more scales. Use oil where Integrated Pest Management (IPM) is practised, and direct the spray at young scales during early November. Ants are attracted to, and feed on the honey-dew produced by the scales. They disrupt natural enemies of the scale and should be controlled by spraying the lower trunk with chlorpyrifos, banding with tanglefoot or distributing an ant bait.

Control methods

Chemical

Petroleum oil (narrow range) is approved for use on longan. Good coverage is important when applying oil to control scales. Note: This information was correct at the time of publication. However, it is the user's responsibility to ensure that registered agricultural chemicals are used in accordance with legal requirements. (See Further Information). Always read the label.

Recommended chemicals

Petrolium oil. The longan industry has recently applied to the APVMA for Minor Use approvals for several insecticides. Refer to a recent edition of Infopest to update the approved list of chemicals on this crop

Biological

Small parasitic wasps such as Coccophagus sp. near rusti and Encarsia sp., periodically cause significant mortality. The Kenyan wasp,  Diversinervus stramineus, is being investigated for release (on citrus).  Ants attend the scale for their honeydew and in so doing disturb potential scale parasitoids. When the ants are controlled, natural enemies are allowed to function effectively, and scale numbers drop dramatically.

The mealy bug predator,Cryptolemus montrouzieri, preys on green coffee scale.

The fungus, Verticillium lecanii , can cause up to 90% mortality of the scale during wet weather in late summer/autumn, particularly when populations of the scale are dense.

Further information

  • Broadley, R.H., Smith, D., Owen-Turner, J.C.,Chapman, J.C., Banks, A.G. and Mayers, P. 1987, Protect your citrus, Queensland Department Primary Industries, Information Series QI87012.

  • Infopest CD-ROM contains current national information on registered agricultural chemicals and is available from Infopest, DPI&F, GPO Box 46, Brisbane Qld 4001 or by email from infopest@dpi.qld.gov.au

  • Smith, D. 1990, Integrated pest management in Queensland citrus, Australian Citrus News 66(12) 6-12.

  • Smith, D. Beattie GAC & Broadley, R. (eds.) (1997) 'Citrus pests and their natural enemies'. Queensland Department of Primary Industries, Brisbane.

  • Smith, D. and Papacek, D.F. 1985, Integrated pest management in Queensland citrus, Queensland Agricultural Journal @b111@b, 249-259.

  • Swaine, G., Ironside, D.A. and Corcoran, R.J. 1991, Insect pests of fruit and vegetables, 2nd Edition, Queensland Department Primary Industries, Information Series QI91018.

  • DPI&F Customer Service Centre on 13 25 23 - local call 8 am to 6 pm Monday to Friday (non-Queensland residents phone 07 3404 6999). E-mail: callweb@dpi.qld.gov.au
Information contained in this publication is provided as general advice only. For application to specific circumstances, professional advice should be sought. The Department of Primary Industries and Fisheries, Queensland has taken all reasonable steps to ensure the information in this publication is accurate at the time of publication. Readers should ensure that they make appropriate inquiries to determine whether new information is available on the particular subject matter.

Last updated 15 December 2005
 

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