In article , Tim
writes
Is there
anything I can squirt along there that'll kill em and deter any from
venturing in?

When camping, we used to squirt a line of washing up liquid around the
edge of the groundsheet - it always seemed to keep them out. It
probably wouldn't persuade them to leave your wall, but it might be a
non-lethal way of stopping them coming into the room - and if that is
where they're looking for food, they might just leave.

--
regards andyw