Asian wasps

[Admin]

...... The best remedy for them is carbaryl if you can get it, but inside a wall like that you really need professional pest control if they get out of hand.

Carbaryl is extremely toxic and potentially carcinogenic. Effective PPE and care in handling is required to prevent causing as much harm to yourself (and your environment) as to the target insects. As you suggest, best left to the professionals.

Yes its hard to find carbaryl these days.
I had an old container that had broken down and been knocked over in my garden shed.
I swept it all up, but concerns me how dangerous this stuff is, ive used a little of it in the past but was not aware of its dangers.