A Saw Point

I've found and ignored a number of sawfly larvae over the course of this year, mainly ones that were swept up by chance from grasses and low vegetation so not possible to accurately pin to a particular foodplant. I also find them difficult to identify compared to lepidopteran larvae. I can usually assign most moth caterpillars to family and often species quite readily, whereas with sawfly larvae I have no clue as to what family it may belong to. Recently I've found a couple that I thought may be identifiable, but as yet I've not been able to figure them out.

Firstly a relatively small larva - actually two of them - found on Rosa sp. down the lane.

What was additionally notable was that both larvae had a small black 'foreign body' apparently attached to the back of the head capsule. I posted these on the sawflies facebook group, and the most plausible explanation was an egg case from a parasitic wasp. Certainly the two larvae were acting lethargic and not feeding - any chance of rearing through pretty much extinct so these remain unidentified.

More recently I found this larva on Sessile Oak, sitting coiled up on the underside of a leaf ....

No firm ID, and trawling through all the species reportedly confined to Quercus sp. does not throw up an obvious candidate. It's possible that this is actually a polyphagous species.

Either way, based on the structure and appearance of the two I am unable to put them to a likely family and narrow down. I've seen a comment suggesting that this (Czech, non-English) book carries a good number of excellent images including larvae:

But I think, whilst frustrating, the only way forward with free-roaming (as opposed to leaf-mining) sawfly larvae is to try and rear through - something I've yet to successfully do but clearly worth a shot.