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Ladybirds fight off insect infestation

How do you solve an outbreak of scale insects on Lady Elliot Island? Release 300 ladybirds to eat the offenders of course!

Ladybirds fight off insect infestation

Lady Elliot Island sits on the Southernmost tip of the Great Barrier Reef. The island is a beautiful coral cay about the size of 50 football fields, nestled within a highly-protected Green Zone of the World Heritage Marine Park.

A sanctuary for over 1,200 species of marine life including whales, manta rays, turtles, dolphins and corals, it also has the second-highest diversity of breeding seabirds of any island on the Great Barrier Reef. 

For decades, Lady Elliot Island was a degraded landscape of bare rock after guano mining destroyed the native vegetation. Past and present island custodians have worked tirelessly to restore the island back to its natural state by removing weeds and planting native coral cay species. 

Last year, a small outbreak of soft scale insect – Pulvinaria urbicola – was identified in the Pisonia forest on the western side of Lady Elliot Island. 

Reiner Richter, Atlas of Living Australia

Reiner Richter, Atlas of Living Australia

Scale insects are native to coral cays, but typically appear in low numbers and are kept in check by natural predators such as native ladybirds and parasitic wasps.  

Outbreaks can cause significant damage to Pisonia forests - on neighbouring Tryon Island a scale insect outbreak stripped more than 90% of the Pisonia forest in less than three years.  

Pisonia is critical to coral cays, providing shelter and breeding habitat for a variety of birds and help protect the area during storms and cyclones. 

Jim Buck

Jim Buck

On Lady Elliot Island, Jim Buck, Ecosystem Management Officer, took action quickly to contain the outbreak. In line with the island’s natural control philosophy, the Queensland Parks and Wildlife Service recommended releasing predatory native ladybirds – Cryptolaemus montrouzieri – to manage the situation.  

Our partner, Lady Elliot Island Eco Resort, distributed 300 beetles across the island – 100 in the outbreak area, 100 in the nursery and 100 in the maturing Pisonia forest that was planted as part of our Reef Islands Initiative revegetation program. 

Jim Buck

Jim Buck

The ladybirds have worked hard and successfully kept the scale insects in check. One year on, they are still playing a key role in keeping Lady Elliot Island’s Pisonia forest and broader ecosystem healthy. 

Find out more about the vital work we’re doing as part of our Reef Islands Initiative here.

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