Poison

[EcclesCake]

Can you buy poison for mice/rats or is it a controlled substance?

[Donquixote]

Yes, you can buy it from most hardware/DIY stores. If you're using it in your house, though, I would recommend traps over poison. Once they take the poison the mouse/rat well generally seek somewhere quiet and sheltered as the effects kick in. Next thing you know, your house is reeking of decomposing rodents and the chance of finding the source is pretty slim. Dead mice in your wall cavities is not a pleasant experience, believe me.

[EcclesCake]

A trap wouldn't work unfortunately. I've found a hole between a window frame and the wall. My plan is to put some poison in and then fill the hole with expanding foam and finishing off with a bit or mortar.

I did wonder if I'd have a problem with the decomposition though....

[chas2008]

i use neosorexa gold, which i get from the local feed merchants..quality product. Living near fields & hedgerows i keep it down all year round in my garage.
The one year i didnt i was overun with the little gits,100+ the smell of live mice (peeing in one place) is probably worse than one decomposing which will only last a short time.

[spudqueen]

But surely the mouse will come out of the hole and that's when you trap it!

[RATTER15]

You can certainly buy some of the best rodenticides over the counter, some however are controlled.