Summer is the most challenging season for honey bees to collect nectar and pollen, according to a new study.

Researchers from the University of Sussex Laboratory of Apiculture and Social Insects (LASI) spent two years filming honey bees in its glass-fronted observation hives.

They then decoded their waggle dances to discover how far the bees were having to fly to find sources of food during different seasons.

The waggle dance, in which the bee waggles its abdomen while moving in a figure of eight pattern, is performed by returning forager bees in the hive to tell its nest mates where to find good sources of pollen and nectar.

The dance indicates the distance to a patch of flowers from the hive and the direction from the hive.

The bees were able to access the surrounding downland countryside and Brighton and Hove through tube tunnels that opened to the outside of the lab.

By examining the waggle dance data, researchers found that in summer, honey bees were covering areas 22 times greater than in spring and six times greater than in the autumn.

The study also showed summer is probably a harder season both because there are fewer flowers but also because there are more insects active at that time, competing with each other for nectar and pollen.

Margaret Couvillon, who led the research, said: "We eavesdropped on what the bees were communicating to each other about where to find good food.

"What they told each other shows that they are finding it harder to find food in the summer than in the spring or autumn.

"In any conservation work, it is important to know where the animal collects its food.

"Some researchers attach tracking devices to the animals they study, which we cannot do because the honey bees are too small.

"But we also don't have to because the honey bee is the only animal that tells you directly where it has collected food."

The results could be used to focus efforts to help bees better, researchers say.