Tuesday, August 3, 2010

Butterflies, Flies, Bushes & Bees

"Butterfly, butterfly where have you gone?
To Buddleja davidii ever and anon."

Anonymous, 2010.

Butterfly bush (Buddleja davidii)

And indeed they do. The butterfly bush (Buddleja davidii) or summer lilac is a tall shrub growing anywhere up to 8m and well known in gardens for the numerous butterflies that are attraceted to the long dense spikes with their fragrant pale purple 4-pettalled flowers. These spikes are in flower around June to September. The leaves are opposite, lanceolate (narrowly oval and pointed, or lance-like), can be toothed and downy beneath. It was a cultivar developed in France in the 1890s and not the original wild Chinese plant. It has become increasingly an escape and can be found on bare and waste ground, particularly in or around towns and suburbs (Wild Flowers of Britain & Ireland, Blamey, Fitter and Fitter, A&C Black, London 2003, pp386).

I regularly encounter this plant as an escape when taking train journeys around Ireland and England. It is often near the track and/or peeping through the railway fencing. This is due to the abundance of associated waste ground.

Butterfly bush (Buddleja davidii)

On taking photographs of the plant recently, I found a few species of insect: a common green-bottle fly (Lucilia sericata), a bumble-bee (Bombus terrestris), a honey-bee (Apis mellifera) and a peacock butterfly (Inachis io).

Common green-fly (Lucilia sericata)

Bumble-bee (Bombis terrestris)

Honey-bee (Apis mellifera)

Peacock butterfly (Inachis io)

Alien plants or animals which become naturalised are often a concern and can cause disapproval among ecologists and conservationists. These species tend to 'take over' from native species and can come to be unwelcome weeds or pests. But buddleia is different: it rarely colonises natural areas, the plant is in no sense a farm or garden weed, and as a result of its special requirements cannot be viewed as a threat to native plants. Moreover, in Britain there must have been a 'vacant niche' for a woody shrub able to exploit dry rubble, old walls, building sites, and similar places, a niche that no native plant could fill so effectively. The Biological Records Centre, Institute of Terrestrial Ecology provide information that suggests buddleia first became naturalised on a significant scale in the 1930s in limestone quarries, on old walls, and on areas of exposed chalk. But not until the late 40s and 50s did the plant experience a population explosion which could be attributed to the sudden availability of sites created by bomb damage and subsequent re-building programmes following the Second World War. In London and other cities, dense thickets formed and since then buddleia has flourished in almost every piece of land where there is rubble. Owen and Whiteway suggest that as a plant increases its range and abundance it might be expected to acquire more and more associated insects: buddleia provides confirmation of this expectation but as is not the case in certain other introduced plants there appear to be no introduced insects associated with it. (D. F. Owen, W. R. Whiteway, Buddleia davidii in Britain: History and development of an associated fauna, Biological Conservation, Volume 17, Issue 2, February 1980, pp149-155).

From China, to France in the nineteenth century, through to the 21st century we are proud to present to you The Butterfly Bush.


The 21st Century Naturalists.

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