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NEWSLETTER No. 15 -  Summer 1986

WEST MIDLANDS BRANCH, BUTTERFLY CONSERVATION

 

Butterflies of the West Midlands

1 - Comma

Identification of the adult Comma should not present many difficulties; the jagged outline of the wings and the white comma-shaped mark on the underside being unique among British butterflies. Identification on the wing is more tricky, and its strong and direct flight can often suggest one of the Fritillaries. Its habit, however, of returning to the same spot often enables a second chance at identification, for the males establish "territories", where they perch for long periods on particular leaves. Tony Drakeford, a member of London Branch, made a study of territorial behaviour in the Comma back in 1982 near his home in
Wimbledon. He recorded a single Comma on a bramble patch for a period of seven weeks from late March to early May. During that time it fought off many challenges from rival Commas and also Small Tortoiseshells but always returned to the original spot. Such Comma "hot spots" seem constant over time, and are even used by successive generations. Those members who undertake regular butterfly walks no doubt have observed this phenomenon for themselves.

This fierce territoriality is one of the reasons why for much of the year the Comma is only seen in ones or twos. The butterfly does not form discrete colonies and the best chance of seeing Commas in number is either in the Spring, fresh out of hibernation, or in late Autumn when the overwintering generation are very partial to ripe blackberries. In 1980, on the weekend after Easter, Roger Smith counted 80 Commas on a walk round Oversley Wood in Warwickshire, but such numbers are probably exceptional. 1984 was a poor year for this species and my maximum daily count was the ten seen at Tiddesley Wood, Worcestershire on 18th September feasting on blackberries. In the autumn the butterflies are much less territorial as pairing does not take place until the following Spring. Commas usually emerge from hibernation slightly ahead of Small Tortoiseshells and Peacocks, but after the Brimstone. My earliest date for this species was March 6th, 1984. They seem to die off fairly quickly and it is unusual to see an overwintering Comma much beyond the end of April. The usual hibernation site is said to be in exposed positions an tree trunks but there seems to be a paucity of information about this. Certainly there is no evidence of the butterfly overwintering in houses or outbuildings like the Small Tortoiseshell. My latest date for the Comma was 3rd November, 1981.

The distribution of the Comma has altered dramatically during the present century. For at least the first half of the nineteenth century it was a very widespread butterfly being found almost up to the Scottish border, but in the latter years of the century it had become confined to a small area centred on Herefordshire, Worcestershire, and the Forest of Dean, being considered by collectors as rarer than the Large Tortoiseshell. From the 1930s onward, it has spread outwards again to occupy much of its former range, and this expansion seems to have continued to the present day. It has become more frequent in the
north of Warwickshire in recent years, while in Staffordshire it has been spreading east across the county. It has also been recorded more often in gardens where it is greatly attracted to the flowering spikes of the Buddleia bush.

The main foodplant is considered to be Nettles, but Hop and Elm are mentioned in most books. The butterfly lays a single glassy green egg on the top of a leaf and it would appear that the same butterfly will lay on more than one kind of foodplant. Back in 1979, BBCS member Brian Wildridge observed a Comma laying a dozen or more eggs on different tiny Elm leaves and then flying on to repeat the process on a nearby nettle bed. It does seem possible that the Comma may suffer as a result Dutch Elm disease, but the availability of alternative foodplants should mitigate the effect. According to J. Heath et al, it will breed readily on regenerating sucker growth and also cut hedgerow Elm. Elm is certainly favoured at some sites; in 1984 I found mature larvae on two separate occasions on Suckley Hills, Worcestershire. The larva is very distinctive, especially in its later stages, when it bears a close resemblance to a bird dropping.

There are two generations, but unusually a proportion of individuals from the first brood are thought to also go into hibernation. The first specimens to emerge each year, typically around the beginning of July in the West Midlands, are var. hutchinsoni which is a paler orange than the normal specimen with less indented wings; the underside is also much paler. The normally marked Commas appear about a fortnight later, but soon hibernate, and it is the hutchinsoni Comma which produces a second overwintering generation in the autumn.

Variation is rare although the comma marking on the underside occasionally forms complete circles, and there was the unusual specimen reported from Haugh Wood, Herefordshire, two years ago, which was plummy-pink in colour rather than orange.

As one of the very few butterflies to have expanded its range in recent years, the Comma is an optimistic choice as a branch symbol. The latest distribution maps from B.R.C. still show some large gaps in Staffordshire and Shropshire and it would be nice to receive further records from these areas. There are also gaps in our knowledge about many aspects of the life of this butterfly and original observations would
be welcome.