Hi,
Small Tortoiseshell will, as I have seen, use anything to suspend themselves from.....anywhere will do, when little is available. I am currently working in a large grain drier on a farm in the Scottish Borders. There is a small nettle patch that was full of Small T Shell Cats in August. Those Cats scuttled of to pupate on walls, sheds and water tanks as well as inside the grain drier building itself!! They are all very much alive and kicking...and should emerge over the next few days.