reserves represent small oases or token sites in areas which have largely been denuded of those
features which are congenial to continued local survival of butterfly colonies.
The combination of climatic variations, habitat changes and an increase in bird and insect
predators has produced the pattern of butterfly populations we see in Essex today. The large skipper
(Ochlodes venata) and small skipper (Thymelicus sylvestris) do not seem to have suffered unduly
from grassland changes and are holding their own. The Essex skipper (Thymelicus lineola) remains
widespread in coastal areas and in many localities well inland. It is probably under-recorded owing to
its similarity to the small skipper with which it flies in July.
The dingy skipper (Erynnis tages) and the grizzled skipper (Pyrgus malvae) have lost ground in
the last 20 years. Habitat change or destruction must be blamed for the decline of these lively little
springtime butterflies which tend to be found in scattered and localised colonies on heaths,
embankments and in more open rides of woodland. There is no doubt that myxomatosis, causing the
disappearance of rabbits from some sites, has allowed an invasion of scrub which has choked wild
strawberry and bird's-foot trefoil, the respective larval foodplants of these skippers.
Among the Pieridae ('Whites and Yellows') there has been one exciting development the dainty
wood white (Leptidea sinapis), missing from Essex for a century, reappeared in a tract of mixed
woodland in west Essex in the summer of 1976 during a period when the species was undergoing an
easterly extension of its range and had been seen in east Hertfordshire the previous year. The wood
white, like many other woodland species, benefits from coppicing and is adversely affected by
management neglect or the widespread planting of conifers.
The brimstone (Gonepteryx rhamni) remains widespread but its larval foodplants, buckthorns, are
collectively fairly widespread and the insect is something of a wanderer. The orange tip (Anthocharis
cardamines) has maintained its numbers well but in some areas may have suffered from the ploughing
or draining of moist pastureland where one of its main larval foodplants, cuckoo flower or lady's
smock, grows plentifully. Fortunately female orange-tips also lay readily on jack-by-the-hedge
(hedge garlic) which is still a common wayside plant in Essex.
Predictably, the hairstreak group of lycaenid butterflies, which frequent woodland and heaths,
have contracted in range and numbers. At times there are population build-ups such as happened to
the purple hairstreak (Quercusia quercus) in the abnormally hot, dry summer of 1976 but in general
terms these lively little butterflies have become much less common. Worst threatened of the group is
the white-letter hairstreak (Strymonidia w-album ) because of its dependence on mature trees of
common elm and wych elm. These are the only larval foodplants and a high proportion of woodland
and hedgerow elms in Essex has succumbed to the ravages of Dutch elm disease. The current status
of the white-letter hairstreak is giving rise to concern as a number of colonies have disappeared from
north and central Essex and, so far as I am aware, there no firm evidence that the species can survive
on regenerated sucker growth of elm in hedgerows. The young larvae require the flowers and buds of
elm or wych elm on which to feed and there is no blossom on sucker growth. A welcome surprise in
1983 was a record of the brown hairstreak ( Thecla betulae) in the Epping Forest area The fact that
there were two separate sightings by a competent observer would seem to indicate that a small colony
of this hairstreak, which is on the wing late in the season (in August) and is somewhat secretive in its
habits, has survived undetected in a woodland area which, although frequently visited by naturalists,
is sufficiently extensive to prevent intensive survey work and could yet produce more discoveries (see
the reference to the purple emperor). As I write this chapter, information has come to hand that a
female brown hairstreak was seen near Braintree in 1974 or 1975.
Among the 'blues' (Lycaenidae) Essex lost its only surviving colony of the silver-studded blue
(Plebejus argus) which survived briefly and precariously in Grays Chalk Quarry area in the 1950s
and died out in 1960. The brown argus (Aricia agestis), though still present in scattered and localised
colonies, is obviously another species in decline: it is still reasonably common in chalky areas of
Cambridgeshire and Hertfordshire where its main larval foodplant, rock- rose, is plentiful; but there is
no evidence that it is able to fan out across the border and establish itself on the chalk of north-west
Essex. One reassuring sign is the sighting of single specimens of this species in north-east Essex in
two widely separated sites. As there are no rock-rose plants in these areas, the larval foodplant is
presumably dove's-foot Cranesbill.
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