Reply from Colleen Foelz at the Queensland Museum about these things
Hi Christine
As you suggest these are sawflies, but to identify the actual species is not straightforward. Most of the descriptive work for identifying species has been done on the adults.
Raising the caterpillar through to its adult form would be the best way to obtain a species identification but we’re not sure of the conditions that would be required to make that successful.
Thank you for the video, it’s certainly an interesting behaviour that this groups shows.
Regards
Colleen
So if we see them again, I guess we better take a sample and try and raise one to maturity 🙂