Annual General Meeting/Publicity Officer - vacancy ............ .4 The Butterflies of Hockley Wood

The Butterflies of Hockley Wood

}:l~I~it::~, by Graham Bailey

Purple Hairstreak by Angie Steele

Over the past twenty years I have

personally noted 26 species of butterfly for Hockley Woods, quite an impressive total for anywhere in Essex at the best of times!

In addition, I recorded the wall Brown back in the early 1980's but unfortunately

not since.

Undoubtedly the most important species now is the Heath Fritillary, introduced from Thrift Wood in 1987 and with its origins therefore in the Blean Woods complex in Kent. The Hornbeam coppice management is principally directed at maintaining the population of this enchanting insect within the woods by removing a one hectare block of trees each winter. The areas to be coppiced are decided annually, these sites being dependent on the distribution and suitability for regeneration of the cow-wheat, the fritillary's larval foodplant here. Some removal of Oak standards is also performed to increase the sunlight reaching the ground; undergrowth is also cut where necessary to encourage the growth of cow-wheat by leaving large patches of bare ground. All these measures are vital for the survival of the butterfly without them the insect would die out within three or four years. Afi:er their initial release, numbers reached a rapid peak in 1991 and 1992, with easily 200 butterflies on the wing at the height of the flight period. The population appeared to dip quite markedly for a season or two following this, but the colony has gained momentum once again and can generally be seen flying plentifully in

June.

One particularly interesting facet of the Heath Fritillaries here is their tendency to have what is almost certainly a second brood. I count myself extremely fortunate to be one of very few people in this country (to my knowledge) who has witnessed this phenomenon, although it certainly occurs on the Continent. .. Having told my friend Don Down of my sightings he explored the site on the 12th September and found two flying; these are possible the latest ever Heath Fritillaries seen in the wild - unless someone out there knows differently of course! Of the other butterflies present, those with grass-feeding larvae are the most numerous; these include the Hedge and Meadow Browns and also the three Skipper species. The Speckled Wood can be very common but the droughts of recent years have not helped it here as elsewhere. Strangely, the Ringlet appears to have only a very tenuous hold, despite it faring much

better in some smaller nearby woods. The regular coppicing has benefited some of the Lycaenids, with 1996 proving excellent for the Common Blue - up to one hundred were counted in two clear areas. I noted my first Brown Arguses here in 1994, the recolonization of the woods mirroring their advance to pastures new as in many other pans of the country. The Small Copper is also seen more frequently, with a few Small Heaths here and there. All the native Vanessids appear more prominent generally in the spring, especially when feeding on sallow, catkins and blackthorn blossom. The Brimstone can be found in reasonable numbers from late March, but as yet I have never found the alder buckthorns on which the females lay their bottle-shaped eggs. I will have to look more seriously next year! The Purple Hairstreak is ofren abundant around the oak canopy on July evenings, and there is also a White-letter Hairstreak colony on the east side of the woods, although many of the larger elms are now badly diseased. I even The above is an extract from the Cambridgeshire & Essex Branch newsletter, Winter 1997 edition and is a personal account of Grahams observations of butterflies in Hockley Wood. We thought this would be of interest to our members in particular those who attended the visit to Hockley Wood last year. We are very gratefal to Graham far letting us reproduce this - Ed.

Small Copper & Small Heath by Beryl Johnson

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managed to disturb a female Clouded Yellow in 1994 from a meadow beside the woods - a chance event on an overcast afternoon! hl-

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