Updated 18 July 2011

Australian Plague Locust

1. What do they look like?
The adult of the Australian Plague Locust is easily identified by the black spot on the tip of its hind wings (see image below) and distinctive orange shanks on their hind legs. Hoppers or immature locusts are more difficult to identify. However, if a large mass (band) of hoppers is found it is likely to be the plague locust.

2. Will there be another locust plague this spring?
Locusts are expected to hatch in South Australia in spring 2011 in areas where adults were present and laying eggs in autumn. These adults were the remnants from the major plague in spring 2010 which resulted in a second generation persisting in low to medium densities over summer and autumn. There were no mass migrations of adults into South Australia in autumn.

Some formation of hopper bands is expected in localised areas, however overall locust populations are not expected to be on the same scale as spring 2010.

3. Will there be an extensive State Government program for combating locusts in spring 2011?
Locust numbers in most cropping areas are expected to be within the normal capacity of landholders to manage through targeted ground spraying or spot spraying in spring. A small, highly targeted aerial program may be required to control bands in some locations in the North (Hawker – Orroroo – Burra). Biosecurity SA will continue to monitor the situation closely.

4. When will locust eggs hatch?
Eggs will hatch in spring into wingless hoppers which will immediately begin seeking green feed. Once they reach adult stage and can fly, control becomes much more difficult. Therefore, it is important to monitor hatching dates and be prepared to undertake treatment.

Projected hatching dates are listed on the Australian Plague Locust Commission website: 
 http://www.daff.gov.au/animal-plant-health/locusts/current#hatchtable  

5. What should I do if I find locusts on my property?
Under the Plant Health Act 2009 there is a legal requirement for landholders and others to report suspected locust detections. We encourage landholders and the general public to report sightings to the locust hotline on 1800 833 451.

Landholders should also undertake their own control measures. Ploughing-in or disturbing egg beds, particularly in agricultural areas, will destroy some eggs; control of hoppers and adults can also be achieved by using various approved insecticides.

6. How can I control locusts on my property?
The most effective way to control locusts is by spraying hoppers on the ground when they have formed into dense groups, or ‘bands’. Chemical spraying is best directed at hopper bands and should not be applied to crops for protection if not affected by locusts.

Time is of the essence when controlling outbreaks of locusts. Hoppers take about two weeks after hatching to form into dense bands that are then suitable for spraying and, overall, about five weeks to form into swarming adults.

Ploughing fields where locusts have laid eggs may have some impact on individual egg beds, but egg-laying often occurs in areas where ploughing is not possible, for example in hard soil along roads or tracks. For more information:

Locust control in horticulture (.PDF)

7.  How can I protect my garden from locusts?
Plague locusts can impact on towns as well as rural properties. Generally, adult locusts will fly in as swarms but these swarms are often not of sufficient size or density to warrant spraying with insecticides.

Strict pesticide protocols prevent large-scale spraying near dwellings, water supplies or other environmentally sensitive areas. Homeowners should first consider cost-effective, non-chemical methods of controlling smaller infestations of locusts:

• Valuable shrubs and plantings can be protected with insect mesh or shade cloth – but not green-coloured as locusts are attracted to this colour.
• Small numbers of locusts are best controlled by catching and squashing them.

Should you decide to spray with insecticides, first seek advice from your local home garden supplier or chemical reseller and use the pesticide only as directed on the label. Further information about control of locusts in the home garden is available on a separate fact sheet.

8. I have bee hives on my property. What should I do?
Bee hives should be moved out of areas before spraying occurs. For further information about locusts and bees, please consult the separate bees’ fact sheet, Locust control and honeybees.
 
9. What insecticides should I use to control locusts?
Only chemicals registered or approved for use by the Australian Pesticides and Veterinary Medicines Authority (APVMA) may be recommended for use. Chemicals registered for the control of locusts contain different active ingredients and are marketed under a range of brand names.

It is important that landowners identify the active ingredient in any chemicals being used on their properties, follow all the associated directions, and understand the potential impacts such as chemical residues in livestock and grain. Advice on the most appropriate chemicals to use can be obtained from local chemical resellers.

We recommend that landowners and farmers establish a diary to regularly record accurate details of chemical spray applications that have been made – when, where and what levels – for future reference and to ensure wasteful or potentially dangerous applications don’t occur.

10. When is the best time to spray?
The most appropriate application methods for locusts can vary with the locusts' life stage and behaviour. Bands of hoppers are the best targets for ground control. Hopper bands are often most compact targets for spraying in the early morning or late afternoon.

Large hopper bands can be sprayed with boom sprays. Isolated and small areas can be sprayed using misting machines or knapsack sprayers. The best results are achieved if control is undertaken when hoppers are in the smallest area.

Dense, high pasture or crops should not be sprayed in still conditions, as wind turbulence is needed for successful spray penetration of the foliage. Hoppers die after contact with, or ingestion of, treated vegetation. This may be 24-48 hours after spraying. Follow-up treatments may be necessary for up to a fortnight after spraying, as several waves of bands can hatch.

11. Are there any risks involved in spraying my crops?
Controlling locusts with insecticides may be necessary to protect crops and pastures, but needs to be carefully considered along with other crop management options available for minimising the risk of damage. Chemicals used have the potential to cause unacceptable residues in grazing livestock – residues that can cause problems for Australia’s export industry.

Any spraying must be done with care especially around sensitive water courses. For more information follow these guidelines.

Also, much of SA's grain production is exported as ‘pesticide-free’. Deliveries of grain will be tested for chemical residues, to detect the use of unapproved pesticides and to ensure that withholding periods have been followed, so that the standards demanded by export markets continue to be met.

Physical contamination of grain with locust bodies and body parts must also be managed at harvest time to ensure grain receival standards are met.

12. What damage can locusts cause?
Adult locusts can cause extensive crop and pasture damage in a relatively short timeframe. They eat any green feed available and concentrate into groups called swarms which make low drifting flights up to 50 metres high. Adult locusts can cover 10 to 20 kilometres a day, but much greater distances under certain climatic conditions.

High density swarms (more than 50 insects per square metre) have the potential to eat up to 20 tonnes of vegetation.

13. Where do locusts lay their eggs?
Females select suitable laying sites by test drilling. They generally prefer the hardest and barest ground available, e.g. roadsides, tracks, fence lines, dry land flats, sparse pasture paddocks etc.

Eggs are laid in pods at a depth of 20 to 50 mm. Each pod contains 30 to 50 pale yellow banana-shaped eggs, 5 to 6 mm long. Each female can lay up to four pods. Eggs develop according to temperature and moisture. Usually eggs laid in autumn are dormant over winter and hatch in the spring as soil temperature increases.

However, eggs laid in summer under ideal conditions may hatch within 14 days.

14. Where have they come from?
Most locust plagues in South Australia originate in the channel country of south west Queensland and New South Wales and the Northern Territory. Widespread rain in south-western Queensland and north-western New South Wales can often lead to conditions where there is a significant build-up of locusts in the region due to the availability of green feed. Adult locusts may then migrate into South Australia. There has not been any significant fly-ins in the lead up to spring. Spring hatchings in South Australia will be the descendants of adult locusts that persisted in our state into this autumn.

15.  How big is the problem likely to be in South Australia this spring?
South Australia is not facing a major locust plague in spring 2011. However, there will be locusts and also band formation in some areas on a much reduced scale compared to last year.

16. When were the last locust plagues experienced in South Australia?
Our State has experienced major locust plagues in 1844, 1871, 1934, 1947, 1955, 1976, 1979, 1992, 1993, 1997, 2000 and 2010.

Minor plagues occurred in 1950, 1969, 1972, 1973, 1974, 1977 and 1984.

Authors: Kym Perry (PIRSA-SARDI) and Michael McManus (Biosecurity SA)

Disclaimer
Use of the information in this Frequently Asked Questions fact sheets is at your own risk. The Department of Primary Industries and Resources, Biosecurity SA and its employees do not warrant or make any representation regarding the use, or results of the use, of the information contained herein in terms of its suitability, correctness, accuracy, reliability, currency or otherwise. The entire risk of the implementation of the information which has been provided to you is assumed by you. All liability or responsibility to any person using the information is expressly disclaimed by the Department of Primary Industries, Biosecurity SA (a division of PIRSA) and its employees.