Like discerning shoppers checking out vegetables on display in a supermarket, bumblebees can spot the best quality flowers from a distance, a study has shown.

They are able to link differences in pollen quality with floral features such as petal colour, singling out those that offer the best nutrient rewards, say scientists.

Bees forage among flowers both for energy-giving nectar, and pollen, which is taken back to the hive to provide food for larvae. Until now it has not been clear how bees identify sources of good quality pollen.

The new study of bumblebees observed under controlled conditions shows how they quickly learn which flowers provide most nutritious pollen for rearing their young.

Elizabeth Nicholls, from the University of Sussex, said: “Bees need to be able to select flowers providing the most nutritious food for rearing their young. Since bumblebees don’t eat pollen when foraging, it was unclear if or how they might be able to assess differences in quality.

“Here we’ve shown that they are able to detect differences in pollen, even before landing, which means they may be able to tell, just from the colour of the petals, which flowers are worth visiting.

Bees taking part in the study were tested individually as they flew through a perspex tunnel.

Pollen samples were laid out in dishes coloured either green or blue. Originally the bees strongly preferred the colour green, but quickly switched when they learned that blue was associated with better quality pollen.