It may not have occurred to you to keep honey bee hives on your rooftop, but there is no reason you cannot. You simply follow the same guidelines that you would if you have a beehive in your backyard or anywhere else. You would be surprised how many beehives are up on rooftops or back porches in cities big and small.

There is a hotel in Toronto, the luxury Fairmont Royal York hotel, opposite Toronto's main railway station, that has installed three bee hives on its 13th floor rooftop terrace to supplement an in-house garden that already provides its nine restaurants with fresh herbs, vegetables and flowers such as edible pansies.

"Last summer, we were up here and talking about how amazing it is that 13 stories in the air, in the middle of downtown Toronto, that ladybugs and bees and butterflies find this and so we got thinking," Executive Chef David Garcelon told Reuters on a tour of the little green oasis.

"I wondered if we could have our own beehives, so I got in touch with the Toronto Beekeepers Cooperative. It was one of those things that just came together perfectly."

"Sixty to 70 percent of everything we eat has, at one stage in its development, been pollinated by bees, so if you're at all concerned about agriculture...then bees are tremendously important," said Cathy Kozma, chairwoman of the beekeepers' co-op and regular visitor to the tiny rooftop enterprise.

There is a growing recognition that bees living in cities tend to produce more and better honey than those kept in the countryside. 'Bees can fly up to five miles for food, but they tend not to stray more than a mile from the hive,' said Davies. 'Many people think the honey crops in cities are of a higher quality than those made by bees in the countryside because there's a near-constant flow of tremendously varied nectar to be harvested in cities from all the parks, trees, gardens and window boxes,' he added. 'If you compare these multiple harvesting opportunities to those offered by the countryside, which tends to be grouped into areas dominated by a single crop which only flowers once a year, it's clear why cities are such good places to keep bees.'

City bees also tend to be livelier sparks than their country cousins. 'The higher temperature of the city means that bees stay awake for longer during the day and are more active,' said John Hauxwell, chairman of the North London Beekeeping Association, who has seen his group's membership double in the last five years.

It takes two million flowers to make one pound of honey, with the average rural hive of 45,000 bees producing 30lb a year. City bees can produce twice that amount. John Buckoke, a musician who has two hives at his home in London, said: 'I have to climb out of a tiny window to get to the flat roof where I've put the hives. It's a wonderful hobby, there's no better way for a city-liver to get back in touch with nature. Every city dweller should have a hive.'