Troubleshooting Mandarin tree troubles in autumn
If your mandarins are dropping early or you’re noticing sunken, rotting patches with a tiny hole at the centre, you’re likely dealing with an unwelcome nighttime visitor – the fruit piercing moth (Eudocima phalonia). This sneaky pest is increasingly making its presence felt across northern and coastal regions of Australia, especially during the autumn months when mandarins are ripening and most vulnerable.
Meet the midnight marauder: fruit-piercing moth
Despite their impressive size, fruit-piercing moths are rarely spotted in the act. These moths are nocturnal, meaning they do their damage under the cover of darkness. They use a strong, needle-like proboscis to puncture the skin of ripe or ripening fruit and suck out the juice inside. What’s left behind is a sunken, soft patch, often with a tell-tale pinprick-sized hole.
Unfortunately, the damage doesn’t stop there. Once the skin is broken, fungi and bacteria quickly take hold, turning that one small puncture into a mushy mess. Within days, entire fruit clusters can start to rot, fall prematurely, or attract even more pests.
Why they’re becoming a bigger problem
The increase in sightings of fruit-piercing moths is due in part to warming climates and a greater abundance of host plants. Their range has expanded, and home gardeners in affected regions now find themselves dealing with infestations that were once rare. Citrus fruits – mandarins in particular – are a favourite target, but other soft-skinned fruits like persimmons and mangoes are also at risk.
No sprays? No problem – go physical
Frustratingly, there are currently no registered home garden pesticides to control fruit-piercing moths in Australia. But don’t worry – this isn’t the end of your citrus crop. Physical exclusion is your best line of defence, and it’s both effective and environmentally friendly.
Try these strategies:
Bag the fruit: If netting the entire tree isn’t practical, protect individual fruit with exclusion bags. You can use mesh bags, commercial fruit socks, or even paper lunch bags secured with a peg or twist tie.
Net the whole tree: Use insect-proof exclusion netting (white, 2mm mesh or finer) to cover your tree entirely. Make sure the netting doesn’t rest directly on the foliage or fruit, as moths can pierce through it.
