Are Christmas Beetles out of balance?

This year was a particularly bad year for Christmas Beetle damage on our Eucalytps and it got me wondering…. Are populations of Christmas Beetles out of balance? Is there something we are doing in our landscape, be it spraying or clearing of habitat, reducing the number of natural predators of Christmas Beetle in our landscape? I don’t have the answers to these questions but I read this article and thought it was too good not to share.
A re-blog from the Crookwell Gazette written by the Upper Lachlan Landcare.
Looking out across the landscape at this time of year you can’t help but notice Eucalypt trees that look like they have been crutched, and many completely shorn, of every visible leaf! Although not all species feed on eucalypt foliage, Australia has 35 native species of Christmas beetles, 21 of which are found in NSW.

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.


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