Ivy is a common and widespread native British plant that flowers in the autumn. It is the main autumn source of pollen and nectar for flower-visiting insects. Flowers are only produced on mature ivy, which has oval leaves. The well-known five pointed leaves are found on immature ivy, which does not have flowers.
The flowers are not showy, and many people are unaware that ivy even has flowers.
This slide show 'Identifying Insects on Ivy Flowers' will help you identify the main types of insects that visit ivy flowers. The most abundant are generally honey bees, social wasps, hover flies, and flies. Bumble bees, other bees, solitary wasps, butterflies generally occur in smaller numbers, or not at all. In southern England you may also see the beautiful ivy bee, which has recently colonized Britain from Europe. It does not live in colonies. Each female builds a small nest in the soil.
Identifying Insects on Ivy Flowers
We have also produced a pamphlet with photos of the main types of insects that you can download here and print - Appreciating Ivy and Its Insects.
LASI is hoping to get the public involved in identifying insects on ivy as a way of monitoring pollinating insects in the UK.
LASI has been doing research on ivy and the insects that visit its flowers:
In 2011 and 2012 LASI PhD student Mihail Garbuzov and Professor Francis Ratnieks carried out a project in Sussex on ivy and ivy flowers. Ivy blooms in the autumn. This project was published on-line in Insect Conservation & Diversity in April 2013. Although ivy flowers are small and green and not attractive to humans, they produce a lot of pollen and nectar and are very attractive to pollinating insects and attract a wide range of insect types including honey bees, other bees, hover flies, other flies, late season butterflies like the Red Admiral, and wasps. One reason why ivy is so important for pollinating insects is that it is abundant and widespread. We surveyed 20 areas, each 200m by 200m. Flowering ivy was present in 10/10 of the urban areas and 6/10 of the rural areas. At a national scale, ivy is found throughout the UK. The project showed that nearly 90% of the pollen collected by honey bees in the autumn was from ivy. It is also an important source of nectar, and 80% of the honey bee foragers we saw on ivy flowers were collecting nectar not pollen, as they did not have pollen in their baskets.
Garbuzov, M., Ratnieks, F. L. W. 2013. Ivy: an underappreciated key resource to flower-visiting insects in autumn. Insect Conservation & Diversity (published on line April 2013).
Abstract
1. Ivy (Hedera helix and H. hibernica) is a common autumn-flowering plant found in Europe, North Africa, Macaronesia and Asia. Here, we use five complementary approaches (pollen trapping, nectar refractometry, local and regional surveys of insects foraging on ivy flowers, local survey of ivy abundance) to evaluate its importance to the honey bee (Apis mellifera) and other flower-visiting insects in Sussex, England.
2. Pollen trapping at six hives in two locations showed that an average 89% of pollen pellets collected by honey bees in the autumn were from ivy.
3. Observations of foraging honey bees on ivy showed that ivy nectar is an even greater target than pollen, as 80% were collecting only nectar. Refractometry of samples from ivy flowers and from honey bees foraging on ivy showed that ivy nectar is rich in sugar, 49% w/w.
4. Surveys showed that the main insect taxa foraging on ivy were honey bees (21%), bumble bees (Bombus spp., 3%), ivy bees (Colletes hederae, 3%), common wasps (Vespula vulgaris, 13%), hover flies (Syrphidae, 27%), other flies (29%) and butterflies (4%). The surveys also showed significant temporal and spatial variation in taxon abundance and proportion.
5. A survey showed that ivy was very abundant on a small scale in both rural and urban areas, being present in 10/10 and 6/10 0.2 × 0.2 km samples within two 4 × 4 km areas respectively.The results show that ivy should probably be considered a keystone species with a high value in the conservation of flower-visiting insects in autumn.