Guide to Australian scarabs?

Hi,
Firstly, I want to know if this guide is accurate: https://cesaraustralia.com/pestfacts/scarabs-and-cockchafers-identification/
Secondly, a lot of iNaturalist observers (at least in the Sydney area) identify June beetles (Subfamily Melolonthinae) but can’t identify them more precisely than that. Is there a guide to more precisely identify June beetles?

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welcome to the forum Carl

I can’t definitively say whether that guide you linked is accurate or not, but I know some of the people working for that organisation, and they seem to be pretty experienced in the field, so I would tend to trust it. However, I think a key thing to note is that the guide is explicitly only for “key agricultural scarab pests”, so there are likely many species, especially in non-agricultural contexts, that are very similar to those depicted. So I think this guide is probably really only usable in that specific context.

Other than keys for specific individual genera, there are no guides for Australia june beetles. One of the problems is that it’s a massive group; there are over 1200 currently described Australian species, with many undescribed as well. Second is that there aren’t really many (?any) experts working on them either, with many of the genera having never been revised in modern times. For the genera that do have keys, in many cases the diagnostic differences are based on genitals or very small/obscure features that can be difficult to see in most photographs.

So unfortunately for now, they’re a very trick group to ID, especially from photos. In many cases, even high quality photos may only get you to a genus ID without the specimen in hand.

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Hi,
Thanks for the reply.
On a side note, according to Wikipedia, Christmas beetle larvae look like that too: https://commons.wikimedia.org/wiki/File:Christmas_Beetle_Larvae_(Anoplognathus_sp.).jpg
But is Wikipedia actually correct? I’ve never seen Christmas beetle adults in my garden (but I do see plenty of Argentine scarab adults). Are the larvae of Christmas beetles really that similar to Argentine scarab larvae?

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I can’t confidently answer that having never seen larvae of either where I then knew what the adults were. I suspect they would be pretty similar though