It's probably common but I've not seen one before. And now I've found two in my conservatory. I live on the outskirts of Leeds. It is a mainly suburban area but it is in fairly close proximity to woodlands and farmland. It was getting on for 20mm long. Any help would be greatly appreciated. (Don't know if it is a fly or bug etc but I thought I'd start with a post under this section of the forum.)
Thanks for the info. To be fair, the fact I now know they are sawflies is good. If it is non-native, it would be interesting to find out more, but my curiosity has been mostly sated.
The area where I found them is a room on the side of the house leading to the garden where I keep all my DIY and gardening equipment - timber, bags of compaost, bark chippings etc. It is possible they were brought in from outside.
Ah. timber! Imported hardword perhaps?
If you can stick it in a jar and are willing to post it off then it would be interesting to have closer look. Would the NHM be interested? If not I can feed it to Guy Knight at Liverpool who is expert in the area.