Common Blue Butterfly Polyommatus icarus
The Common Blue is a small butterfly with a wingspan of just
over 3 centimetres. Males have blue upper wings, while those of
females vary from brown to blue. The undersides of the wings are
grey-brown with dark spots. Two generations of the butterfly are
produced each year; the first in May/June, followed by a second in
August/September. The Common Blue is characteristic of species-rich
grassland. The butterfly can maintain small populations and
colonise suitable habitat over distances of a few kilometres. The
larva feed on trefoil plant species, such as Black Medick (Medicago
lupulina), the main larval food plant being Birds-foot-trefoil
(Lotus corniculatus).
Current Status
The Common Blue is widespread in mainland Britain, although
declining in range. The species is not threatened within Europe. It
is not listed as a species of concern by Butterfly
Conservation.
The Common Blue is scarce in Hull. It is found on waste ground,
verges near Priory Sidings and has been seen in recent years on
Cumbrian Way and around Bransholme Fishing Lake. A very small
colony exists in Pearson Park Wildlife Garden and it is found along
rail embankments throughout city. The main larval foodplants
locally are Common Birds-foot-trefoil and Black Medick, growing in
natural and semi-improved grassland, wasteland and verges in sunny
sheltered positions.
Current Factors Affecting the Common Blue
Destruction of semi-natural grassland for urban development.
Improvement of natural grassland with fertilisers or reseeding with
Rye Grass (Lolium spp.).
Changes in agricultural practice, for example the increased use of
pesticides for crop protection and ploughing right up to hedgerows,
has led to loss of field margins as breeding habitat.
Current Action
Legal Status
The Common Blue butterfly is not legally protected.
Management, Research and Guidance
Butterfly Conservation is in the process of producing plans for
'Butterflies of the Wider Countryside' which should include the
Common Blue.
With the aid of the Countryside Stewardship Scheme areas of
Priory Meadows and Snuff Mill Fields have been managed as hay
meadows. This management practice will be beneficial to the Common
Blue butterfly as well as many other grassland species.
Action Plan Aims
- To manage natural and semi-natural grassland to maintain and
increase floral diversity.
- To remove illegally grazing horses where they are damaging the
diversity of flower species.
- To relax mowing regimes on grass verges, flood banks, amenity
grassland and species-rich grasslands.
- To continue Countryside Management Scheme at Priory Meadows and
Snuff Mill Fields.
- To monitor the population and distribution of the Common Blue
butterfly in Hull.
- To use the Common Blue butterfly to highlight the importance of
less frequent grass verge mowing.
What We Are Going to Do
Action
|
Target
|
Partner
|
Aim
|
|
Policy and Legislation
|
| No policy or legislation proposed. |
|
|
|
|
Habitat Management and Protection
|
| Relaxation of mowing regimes on grass verges and
floodbanks. |
Short Term: Review mowing regimes
Medium Term: Relax mowing regimes where possible. |
KuHCC (Highways), EA |
3 |
| Leave margins uncut on amenity grassland. |
Short Term: Develop two example sites.
Medium Term: Uncut margins on 50% of playing fields.
Long Term: Uncut margins on all playing fields. |
KuHCC (Parks and Open Spaces) |
3 |
| Manage areas of grassland as hay meadow. |
Ongoing: Priory Meadows, Snuff Mill Fields and other natural
grasslands to be cut once a year for hay. |
KuHCC (Planning, Parks and Open Spaces) |
3, 4 |
| Remove horses illegally grazing on species-rich grassland. |
Short Term: Removal of horses from Priory Meadows and Snuff
Mill Fields.
Medium Term: Remove horses from other important grasslands. |
KuHCC (Property) |
2 |
|
Advisory
|
| No advisory action proposed. |
|
|
|
|
Future Research and Monitoring
|
| Review of amenity grassland, grass verge and river/drain bank
management. |
Short Term: Review mowing regimes. |
KuHCC (Highways, Parks and Open Spaces), EA |
3 |
| Monitor numbers and distribution of Common Blue butterfly in
Hull. |
Ongoing: Annual monitoring of Common Blue butterfly in
Hull. |
YBC |
5 |
|
Communications and Publicity
|
| Use the Common Blue butterfly to illustrate the purpose of
'unkempt' verges. |
Medium Term: Article in local press highlighting importance of
grass verges for Common Blue butterflies. |
YBC |
6 |
| Highlight Birds-foot-trefoil as foodplant at Pearson Park
Wildlife Garden. |
Medium Term: Publicity to highlight importance of providing
food plants for butterflies. |
KEG |
6 |
What We Can All Do
- Let the Biodiversity Partnership know if you see
Common Blue butterflies in Hull.
- Be aware of the need for areas of uncut grass to encourage and
protect wildlife. Areas of less disturbed grassland are essential
in the lifecycle of this butterfly.
Links With Other Action Plans
The management of Grassland habitats will be particularly
important for the survival of the Common Blue butterfly in Hull.
Species-rich grassland also often occurs on under-used Industrial
Land.
References
Asher, J. et al. (2000) The Millenium Atlas of Butterflies in
Britain and Ireland. Oxford University Press, Oxford.
Hofmann, H., Marktanner, T. (1995) Butterflies and Moths of
Britain and Europe. Harper Collins Publishers, London.
New, T.R. (1991) Butterfly Conservation. Oxford University
Press.