The stuff seems to be having little effect on the mice. Inspecting the
"food troughs" I have left around the attic I note that almost all the
grain as been eaten and I am left with a considerable pile of blue skins
or husks which was the coating from the grain.
Its remarkable, but I suspect I am feeding rather than poisoning my
mice.

The grain is dyed blue as a warning to humans. The poison is within the
grain. Don't worry about the husks, it's just that your mouse tribe don't
like the roughage

Al.