Adults (some commonly known as King Beetle or the Washerwoman) lay their eggs in the soil and larvae, with their distinctive ‘C’ curl, feed on dead plant material when young and move onto root stems as they mature. Pupation occurs beneath the soil and generally after rain, adults emerge and start their feeding.
The whirl of a brightly reflective Christmas beetle cruising by confirms Santa is pretty close. According to the Australian Museum’s website, places like Sydney are seeing massive reduction in numbers, based on anecdotal reports from the 1920s. All that concrete and bitumen leaves limited grassy woodlands for larvae and adult beetles to feed on.
This is cold comfort for us in the Upper Lachlan with grassy woodlands a plenty. Adult feeding appears as jagged, ripped leaves and often occurs on mass. Swarms of adults can literally defoliate eucalypts overnight, rendering spraying at this late stage futile. And without doubt, even mature trees will eventually die following years of repeated defoliation.
Early spraying, as new foliage appears, on young trees can be effective. Shallow cultivation can be risky, as eggs and larvae could be destroyed but bare ground may actually encourage adult egg laying. There is also the potential to damage tree roots and invasion by weeds.
So, when you plant a tree, plant two. A landscape without our beautiful trees would be as heartbreaking as the damage caused by these ravenous beetles.