Beetles devouring our lilly pillies

Over 12 months ago I spotted a bright green beetle on the outside of the window. It was similar in size and shape to a ladybird, but instead of red and black it was bright green.  I took a photo, admired its shiny shell then promptly forgot about it.

The deck in our backyard is bordered by several lilly pillies which have been looking sparse.  I took a clipping to the local nursery and they suggested I spray the trees with EcoPest oil, an insecticide which uses paraffin oil as an active ingredient.  I did this, and repeated the process several weeks later in order to eliminate any pests which might have hatched since the initial spray. Hoping I’d eliminated the pest, a month or so later new growth appeared on the trees and they were starting to look healthy.  A few days after spotting the new growth, I noticed the leaves were being eaten again.  The pest oil hadn’t solved my problem. Then, one morning while enjoying breakfast in the sun I spot the culprit – one of the bright green beetles I’d been admiring a year earlier!

As you can see in the video above, these little guys love to munch on lilly pilly leaves and can get through them pretty quickly!  Having caught them in action, it was time to identify the beetle and work out how to get them under control.

There’s quite a lot of content on the internet identifying these beetles as the green striped beetle, however as I read on the Coffs Harbour Garden Club website it was recently identified as paropsides calypso, an Australian native beetle originally from northern New South Wales which has spread to most of the east coast of Australia. In addition to the article on the Coffs Harbour Garden Club site, there’s an interesting podcast from Real World Gardener which is available on the Garden Drum blog.

According to both these sources, the the beetle generally hides in the soil during the day and feeds at night.  From my own experience, the beetles are more active of an evening when the plants are shaded but it is still light outside.  I’ve also seen them active on some warmer mornings. Both the beetles and their larvae, pictured below, feed on the leaves of the lilly pilly.  The larvae are a paler green than the beetle, and appear glossy as they are sticky to touch.

Paropsides calypso larva

Searching online I haven’t found many options for controlling this pest.  Over the past few weeks I’ve gone outside every couple of days to catch the beetles myself. They can be tricky to spot, but don’t move very fast so they’re not hard to catch.  Occasionally they’ll fly away, and sometimes drop from the tree if you knock the branch so it’s worth having one hand under the leaf as you reach for the beetle to catch it if it falls. Dropping it into soapy water is an effective way of drowning the beetles as the detergent breaks the surface tension preventing them from floating on top.  Over the past few weeks I’ve caught 134 beetles and 12 larvae.  Initially the numbers were around 20-30 in one hunt, but now are down around 10 at a time, so I’m hoping this is impacting the population and they’re starting to decline.

I’ve also been watering the plants regularly with Seasol and new growth is starting to develop. I’m hoping the plants will be more resilient if they’re well fed, and regular hunts will maintain the beetle population. The Coffs Harbour Garden Club also suggested diatomaceous earth as a possible way of preventing the beetles so I might head to the nursery and buy some of this to sprinkle over the soil.

If you’ve come across these beetles in your own garden, post a comment below to share your experience. Have you found an effective method of controlling them? I’m really keen to hear how anyone else has dealt with these beetles.

On a slightly more positive note, I was quite excited this morning to find what appeared to be a spider feasting on one of the beetles. It’s good to know I have an ally in this battle!

Spotted – this spider was feasting on a beetle!


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