Almost 12 months on and I have an update on the beetles which are eating our lilly pilly plants. At the time of writing my previous post on this topic, I had thought maybe my hunting had had an impact on the beetle population because throughout January and February I only caught a couple of beetles and larvae. I continued to fertilise the plants throughout this year, both with Seasol and a separate slow release fertiliser, and they started to thicken, particularly throughout April – May during autumn.
Now, with Melbourne in the middle of spring there is plenty of new growth on the trees and I was excited to think they would finally start to thicken. But then the new growth started to thin, and leaves were being eaten. The paropsides calyspo beetles had returned.
It seems my efforts last year were not successful, and instead of being eradicated the beetles just weren’t active. I suspect they laid eggs at the end of summer, and the eggs laid dormant until conditions were right for them to hatch and flourish. It does, however, feel like I’ve had some success in the past few weeks which is why I’m writing this post to share my findings.
Last year when I was catching beetles, and now this year catching their larvae, I kept a count of the numbers I was seeing. Granted my activity would have impacted the overall population size, but I believe this gives a good indication of when they’re active. As you can see in the chart above, October in Melbourne seems to be the prime time for the larvae to hatch and move throughout the plant as they grow and develop into beetles. One week in the middle of October I caught 180 larvae! Then throughout the rest of spring and then summer the beetles dominate. Last year the most I caught was 50 at the end of December. In January summer really kicks in, so perhaps the weather starts to become too hot for them and they cease to be active. It is worth keeping these time frames in mind when trying to deal with this pest, as late September or early October is probably the best time to start treating the plant with pesticide.
Based on a comment by Ben on my previous post, a two weeks ago I sprayed our plants with a combination of eco-neem and eco-oil. These work by suppressing the insect’s urge to eat so they effectively starve to death. Eco-neem apparently works on the beetles, while eco-oil is more effective on caterpillars. I found these in the pest control section of Bunnings, and expect they would also be easy to find at any nursery. Having applied two coats, I’ve only seen 3-4 larvae and beetles since. Given the number of larvae I squashed, I think that will have had an impact on their numbers as well, but I’m hopeful this treatment will help to put an end to their reign over my plants. I’m going to continue this for the next few weeks with a combination of regular fertilising and hopefully by the end of spring the plants are happy and healthy.
To help you locate these pests on your own plants, here are some things to keep in mind:
- Larvae are pretty small, ranging from 1mm in length up to 1cm.
- They’re normally light green, but as they mature they take on a redish tinge
- They’re often found at the end of branches chewing on fresh growth (in particular the fine red growth)
- You might also find them crawling along branches
- The beetles are similar in size to a ladybird (7-8mm long and 3-4mm wide)
- They’re bright green in colour
- They are less likely to be contained to fresh growth, and quite happily chew through older leaves
- They’re often on the underside of leaves and less like to be on branches as they can fly from leaf to leaf
- Shaking branches can cause them to fall or fly out making it easier to find them and catch when they land
Here are a few photos so you can get an idea of what the beetles and larvae look like, as well as an indication of their size.