Rain and cold weather this summer saw honey yields from hives fall by almost three-quarters, the British Beekeepers Association(BBKA)said today. The average crop per hive was down 72% compared to last year, with just 3.6kg (81b) of honey produced compared to an annual average, the annual honey survey by the BBKA revealed. The survey of 2,712 beekeepers in England, Northern Ireland and Wales found that 88% said this summer's bad weather caused the _ in honey yields. The bad weather made it difficult for bees to excrete ,which led to disease easily, and the bad weather also increased the risk of keeping bees for heavy rain caused the places which bees regularly visited to meet natural disasters. The bad weather also influenced the plants flowering which increased the cost of keeping bees. The BBKA issued a midsummer warning to feed bees if necessary to avoid dying from hunger. But in London, which recorded the worst results with just 2.5kg (5.61b)of honey harvested on average, beekeeping experts said that in addition to the bad weather there was a lack of food for bees in the city. Angela Woods, secretary of the London Beekeepers Association, said, "Rather than putting beehives on office roofs, we encourage companies in London that want to help to look at different ways of supporting bees and beekeepers. We need more food for the bees and better-educated beekeepers." Elsewhere, the weather was the main problem. Peter Hutton, a beekeeper in Tunbridge Wells, Kent, said, "It has been the most difficult year I have known in my 53 years of beekeeping. Bad weather in spring prevented bees in many areas from collecting nectar from early-flowering crops such as oilseed rape ,and the rain continued in many places throughout June and July, preventing honeybees from searching for food on later crops." The BBKA warned that as well as reducing the honey harvest, the bad weather is likely to have a longer-term influence as it will have affected the normal process of breeding for the queens, which mate on the wing on fine, still summer days. As a result they may have mated poorly and be unable to produce enough new babies to see groups through the winter. According to the passage, last year the average crop per hive might be  _  .
5 kg 7.2 kg 10kg 13 kg