Gardens are more important than ever as a source of food for a wide variety of insects who feed on the nectar and pollen found in many flowers: pollinators such as bees and butterflies are in decline globally, with one of the main causes being the loss of flowers, especially in the countryside.
As popular support for wildlife continues to grow, gardeners are increasingly looking for ways to help bees and other insects by providing attractive flowers in their gardens for insects to feed on. To do this, they often rely on “pollinator-friendly” plant lists. But these lists are generally based on opinion and experience rather than scientific research.
The study, funded by the Body Shop Foundation, involved repeatedly counting flower-visiting insects over two summers as they foraged on 32 popular summer-flowering garden plant varieties in a specially planted experimental garden on the University’s campus (each variety in 2 1x1m beds), with two smaller additional gardens set up in year two to check the generality of the results.
Plant varieties studied included 19 species and hybrids, both native and exotic to Britain, with particular focus on 13 varieties of lavender (Lavandula spp.), as it is known to be attractive to bees, and also four dahlias. All the plants studied had to be popular garden plants, be widely and easily available for purchase, and had to flower mainly or exclusively in July/August.2
One key result found by researchers Professor Francis Ratnieks and his PhD student Mihail Gaburzov was that garden flowers attractive to the human eye vary enormously (approx 100-fold) in their attractiveness to insects, meaning that the best plants for bees and other insects are 100 times better than the worst. So it pays to make an informed choice of plants from the thousands available to gardeners.
Bees (87 per cent) and hoverflies (nine per cent) were the most frequent visitors, with butterflies and moths just two per cent and all other insects also two per cent. The researchers observed clear differences in the mix of bee and insect types attracted by different varieties, indicating that careful plant choice can not only help insects in general, but also help a range of insects.