Tiny beetles with a big job to do

The trees scattered around Alf Smedley Reserve at Glenelg North, and some street trees in Glenelg, are now home to around 1000 ladybird beetles.

But don’t be fooled by their tiny size. The native beetles are fierce predators and they have soft scale insects in their sights.

Around 1000 of these bugs were recently released onto trees in the reserve and on street trees around Glenelg in a bid to tackle outbreaks of mealybugs and soft scale insects.

The ladybird beetles prey on the pest insects, which if left untreated, can kill the trees slowly, by draining them of sap.

Scale is a tiny insect that attaches itself to leaves and stems and produces a protective shell over itself. Signs of scale include yellowing leaves, drooping leaves and stunted growth. Mealy bugs cause very similar issues, which can eventually cause the tree or plant to die.

The pests are mostly targeting ficus and fraxinus trees but its hoped the ladybird beetles will reduce the need for chemical treatments as they are a natural predator to the pest insects.

In 2022, around 400 ladybird beetles were released onto the Norfolk Island Pine trees that line the coastline, again as a biological control measure against a mealybug outbreak with great success.

The ladybirds’ scientific name is Cryptolaemus and according to the Bugs for Bugs website, they are very efficient predators of many species of mealybug and soft scale insects.

They’ve been recognised worldwide as effective biocontrol agents of pest insects and they have been exported to many other countries.

Back in 1891, these ladybirds were exported to the United States, where they saved the Californian citrus industry from the mealy bug plague.