There was a bloke on TV the other day who pours molten Aluminium down ant's nests. When it all cools down he digs it up and it looks really neat. A three-dee map of the nest. It also solves the ant problem in no small way. Like the powder, it isn't good for your skin.
(SM) I wonder. The ant's nest would have to be very dry or there'd be an explosion of steam, hot metal and pyrolysed ants. Not nice. Where does he get the aluminium from? He could melt down old saucepans, I suppose, but molten aluminimum is hot, 660°C plus, incipient red heat.