Gardeners can help the bumblebee an insect that is badly threatened in many countries, by growing red flowers or flowers with stripes along their veins, according to a new study.

British scientists made the discovery after watching bumblebees forage for their food on a plot of snapdragons (Antirrhinum), a popular garden plant that comes in a variety of strains.

Bees overwhelmingly chose to visit red flowers or flowers with striped veins, compared with white and pink flowers, the investigators found.

"Stripes provide a visual guide for pollinators, directing them to the central landing platform and the entrance to the flower where the nectar and pollen can be found," said Cathie Martin, a scientist at Britain's John Innes Centre.

The study appears in a British journal, New Phytologist.

Bumblebees, like their cousins the honey bees, play a vital but often unseen role in agriculture by pollinating plants and trees.

By some estimates, the bees carry out work worth more than $200-billion (about R1.4-trillion) a year.

Bee colonies in many countries have been devastated by a wide but poorly understood range of causes. Habitat loss, pesticides, viruses and fungus are among the mooted culprits.

, an insect that is badly threatened in many countries, by growing red flowers or flowers with stripes along their veins, according to a new study.

British scientists made the discovery after watching bumblebees forage for their food on a plot of snapdragons (Antirrhinum), a popular garden plant that comes in a variety of strains.

Bees overwhelmingly chose to visit red flowers or flowers with striped veins, compared with white and pink flowers, the investigators found.

"Stripes provide a visual guide for pollinators, directing them to the central landing platform and the entrance to the flower where the nectar and pollen can be found," said Cathie Martin, a scientist at Britain's John Innes Centre.

The study appears in a British journal, New Phytologist.

Bumblebees, like their cousins the honey bees, play a vital but often unseen role in agriculture by pollinating plants and trees.

By some estimates, the bees carry out work worth more than $200-billion (about R1.4-trillion) a year.

Bee colonies in many countries have been devastated by a wide but poorly understood range of causes. Habitat loss, pesticides, viruses and fungus are among the mooted culprits.