Like most people who live in the country, I get regular invasions of mice. Luckily for me I do not suffer, as some people undeniably do, from real rodent horror, but I am not prepared to share my house with them.They are indiscriminately greedy and skilful foragers, working their way through cardboard and plastic to reach chocolates, biscuits and other edibles; they are dirty and leave their little black faeces all over the place; they chew through paper (books for example), cloth and, famously, electrical cable (my home insurance is specifically invalidated if I have taken inadequate measures to exclude them). Ultimately I do not like them and will not tolerate them.I police my borders to control such illegal immigration. I have a plug-in electronic gadget that emits some noise that I ca