By Marc Carlton and Helen Bostock Reviewed by Steve Head
Part of the joy of being a wildlife gardener is to observe the interaction of wildlife with the plants that we grow. Plants are used by animals in many different ways but in this section we will focus on the special relationship between flowering plants and their insect visitors, what we collectively call ‘pollinators’.
Most people think first of honeybees as pollinators, but there are many more insect pollinators including bumblebees, solitary bees, some wasps, hoverflies, most butterflies and moths, and even some beetles. Collectively, these other species are probably more important pollinators, and the honeybee is an introduced species to Britain. It probably originated in Africa, and before its arrival our native wildflowers managed without it.
These tiny beetles swarming over a Magnolia grandiflora flower are the pollinators for this very primitive plant.
Native is best?
It is a common assumption that that only ‘wild’ or ‘native’ plants in gardens can support pollinating insects, but as you can find on our page Gardens: native or non-native species? , the evidence does not support it.
Herbaceous borders, herb gardens and cottage gardens can be full of bees, hoverflies and butterflies without recourse to any ‘native’ species of flowers at all. The insects have no knowledge of whether the flowers are classified as “native” or “cultivated” by gardeners and naturalists. Their priority is simply to find energy-rich, accessible food as quickly and efficiently as possible, and many kinds of ‘non-native’ flowers serve this purpose just as well as, or better than, ‘native’ flowers, provided their flowers are accessible. This is one of the topics described in “Background to Pollination and Pollinators” (see left) which gives much more information about pollination issues, and the co-evolution of insects (and some birds) and plants.
Planting for Diversity
A typical cottage garden or herbaceous border will have flowers of many shapes to suit different insects, and it is a rewarding exercise to study each type of flower and see what kind of insects it will attract. It follows that to provide forage for a wide range of insects you need to plant a diverse range of flowers of different shapes and sizes. Add to this the fact that you need to provide forage across the whole season from spring to autumn by planting a succession of flowers. It saves visiting insects valuable time if large stands or groups of the same species are planted, as they can focus on exploiting one kind and do not have to learn to access a series of different flowers.
Good plant choice and use is one of the best ways to maximise our gardens for pollinating insects, and here are some simple tips.
Bird pollinated exotics (see “Background to Pollination and Pollinators”) are not usually any value for our insects, but there are some exceptions. Honey bees and social wasps have been seen nectar robbing the long red tubular flowers of Lobelia tupa (see left), and there are some cultivars of New Zealand flax Phormium and red hot poker Kniphophia which are exceptions to the general principle and are regularly visited by bumblebees. If you notice bees using these cultivars when you are visiting a garden or nursery, then these are ones to choose if you want to grow these exotic-looking and architectural plants in your own garden and still provide forage for insects.
It would seem an easy job to compile a list of plants that attract insects to the garden, but there are as many different lists as there are books and web sites on wildlife gardening. Most are largely based on personal observation and anecdote, and although they are very helpful they cannot be taken as definitive. There are many inconsistencies between such lists, and we cannot at this stage recommend any single list on its own, some for example are aimed at one type of pollinator, such as the honey bee.
Here are some web-based lists we recommend:
RHS Plants for pollinators (the most complete list to date)
Bumblebee Conservation Bee Kind Tool
British Beekeepers Association (BBKA) list of trees for bees
British Beekeepers Association (BBKA)list of shrubs for bees
Marc Carlton's Nectar plants for moths
Marc's short pollinator plant list
Plants for bats that attract moths and other night-flying insects
The Wildlife Gardening Forum will be making up our own lists, as far as possible based on evidence and consensus, and will be looking to wildlife gardeners to help. To be most useful. lists should take make allowance for where the garden is located, and the soil conditions. A good example of a local list is that prepared by Jan Miller and Marc Carlton for the Welsh Pollinator Taskforce, which you can download with the button on the left.
Even if you are not a ‘plantaholic’ who collects a particular genus such as Rosa or Clematis, you could, through observation and recording of insect visits, work out which cultivars have flowers that offer good nutritional rewards to insects, and which kinds of insects in particular they attract. There are still large gaps in our knowledge of the value to insects of specific cultivars, and there may well be a role for home gardeners here to do a bit of ‘citizen science’.