HI All(sorry of this isn't posted in the right place!)
This is some house. There are big gaps in the skirting down underneath the suspended floor which is street level.
I wanted to check for rats so put 'DeadFast' sachets on the floor by the holes about 2 weeks ago. After about 3 days the two sachets vanished.
So after another week I left out another 2 sachets and they were gone in the space of an hour.
That night I put another 2 out and again they were gone quickly.
I reasoned that whatever is eating them would take the sachets under the suspended floor where all the rats could have a nibble and then croak it.
But this stuff seems to be doing nothing, either that or there must be some amount of rats down there.
I think I'm going to give up trying to kill them now and spray expanding foam into the holes.