Spotlight on Cheshire butterflies: the Peacock (Inachis io)

The Peacock, with its spectacular wing markings, must be one of the most familiar and easily recognised butterflies in the United Kingdom. It is from the pattern of eyespots on its hindwing, which have evolved to confuse predators, that this large butterfly derives its vernacular name. The species is a common and widespread resident in the south of Britain and Ireland, but is less frequently found further north, especially at higher altitudes.

Early publications reveal that in Cheshire the butterfly was not always as numerous and widespread as it has become in recent years. Ellis (1890) described it as “tolerably common”, whilst Day (1903) revealed that it “appears to be scarce in East Cheshire”. Even in the early 1970s the Peacock was still only being recorded in very small numbers in the eastern half of the county. Since that time the butterfly has continued to expand its range throughout Cheshire, with survey work revealing that since 1990 it has been recorded in 91% of all tetrads in the county. Nowadays, it is not unusual for small numbers of insects that have wandered from their main breeding sites to be found in the more inhospitable areas of the Pennine foothills.

The Peacock is a long-lived butterfly with a single emergence from late July to mid-August, depending on weather conditions. This emergence is often synchronised with good numbers appearing throughout the county within a few days of each other. A feature of the last few years has also been the large concentrations of insects that have gathered at favoured sites during this period:-

73 at Walton Lock (Warrington) on 8 th August 1997.

262 at Rixton Claypits on 12 th August 2000.

100+ at Fiddler’s Ferry on 29 th July 2001.

72 at Hooksbank Wood (Bollin Valley) on 15 th August 2001.

198 at Rixton Claypits on 16 th August 2002.

This nomadic butterfly breeds in a wide range of habitats, but is most abundant in areas of open woodland wherever large patches of nettle occur. It lays its eggs in large clusters on the underside of young nettle-leaves, but it is the larvae that will be most frequently seen by the majority of observers. These black spiny caterpillars are very conspicuous when seen in their communal webs engulfing patches of nettle. The best time to look for them is during June when many plants will have been stripped bare by the feeding damage, prior to the larvae dispersing separately to pupate.

Following emergence the adult insect requires an abundant source of nectar in order to prepare for hibernation. It is at this time of year that it often moves into gardens in the greatest numbers – frequently congregating on buddleia bushes. On some occasions it my find it necessary to disperse over a considerable distance as occurred during the hot weather of 1995 when many flowering plants in lowland areas of Cheshire had withered or died. During this period large numbers of the Peacock butterfly were observed in the Pennine hills where in normal circumstances only a few individuals would have been recorded. At these higher altitudes conditions were more favourable with many nectar-rich plants, especially roadside thistles, proving attractive. Between 29 th July and 10 th August double-figure counts were recorded from 10 upland sites in the county including the following:-

137 around the Cat & Fiddle Inn and nearby Danebower on 30 th July.

42 in the Todd Brook Valley on 10 th August.

For reasons that are unclear the Peacock enters hibernation earlier than its near relatives, the Small Tortoiseshell (Aglais urticae) and Comma (Polygonia c-album). Many butterflies have already commenced hibernation during September, even though warm conditions would seem to encourage them to continue taking nectar to improve their chances of successfully surviving through the winter months. Hibernation occurs in a variety of habitats, but dark corners of unheated buildings or inside hollow trees are often the preferred choice. At these localities the black underside colouring of the Peacock’s wings provide excellent concealment.

References:

Asher, J. et al. (2001). The Millenium Atlas of Butterflies in Britain and Ireland.

Cheshire Butterfly Recording Scheme data, via Levana software package.

Day, G.O. (1903). A list of Lepidoptera found in the counties of Cheshire, Flintshire, Denbighshire, Carnarvonshire, and Anglesea”.

Ellis, J.W. (1890). The Lepidopterous Fauna of Lancashire and Cheshire.

Written by Barry Shaw for News, the Cheshire and Peak Distrcit Branch of Butterfly Conservation magazine.