A change of diet?

In September 2012 we posted a brief story about Fireblight Beetles (Peltoschema orphana) attacking local wattles (see What’ll happen to the wattles ?). The wattles mentioned were those with feather-like (bipinnate) foliage: Silver Wattle (Acacia dealbata) and Black Wattle (Acacia mearnsii).

Driving through Mt. Disappointment Forest the other day we noticed many dense stands of Cinnamon Wattle (Acacia leprosa) that had been severely defoliated (see picture below). Inspection of the few remaining leaves revealed quite a number of small beetles like the one shown above which, we think, is the adult form of the Fireblight Beetle larva shown in the previous post. All references we have found only mention bipinnate wattles as host plants for both the adults and larvae of Fireblight Beetles. Apparently these beetles were a serious pest in wattle plantations established early last century to provide bark for the tanning industry.
So, are Cinnamon Wattles a recent addition to the Fireblight Beetle’s diet ? We would welcome comment from anyone who has come across this sort of defoliation before. Interestingly, nearby stands of other post-fire regrowth wattles in the forest such as Mountain Hickory Wattle (Acacia obliquinervia) and Narrow-leaf Wattle (Acacia mucronata) appeared to be unscathed, but Silver Wattles around the Strath Falls area again looked scorched, indicating attack by Fireblight Beetles similar to last year.

[Click on photos for a closer look]