long hot summer but we understand that this strong flyer is currently extending its range in southern
England.
The large tortoiseshell (Nymphalis polychloros) has always been a local insect subject to
considerable fluctuation in both numbers and range. Today it is a national rarity. The woods in north
Essex and south Suffolk were for long regarded as a stronghold and an extension of range which
began in the 1930s led to its becoming widespread in Essex for some years from the mid-1940s. Its
subsequent decline was rapid, and it could not be found even in its north Essex haunts after 1954.
Only five individuals have been seen in Essex, for certain, since 1956 and all were on or near the
coast, leading to the theory that they were immigrants.
That magnificent butterfly, the Camberwell beauty (Nymphalis antiopa), is an immigrant, usually
rare, from Scandanavia. Essex has had its fair share of sightings of this insect even so, only nine were
reported between 1925 and 1975. The year 1976, however, saw the Camberwell beauty's largest
immigration since 1872 and there were records of 14 individuals in various parts of the County.
Essex has gained - strictly speaking, regained - only one butterfly during the post-war years, a
period which has seen the complete or virtual disappearance of several species from the Essex scene.
This is the speckled wood (Pararge aegeria), an attractive member of the family of 'browns'.
Harwood (1903) recounted that it had been common in the 19th century but had practically
disappeared by 1900. During the ensuing half century there were only a few isolated and well
scattered sightings but recolonisation of Essex from the south began in the mid 1950s and, as the
systematic list and map reveal, this butterfly is now to be found over extensive areas of the
County.
Despite its name, the marbled white (Melanargia galathea) is another 'brown'. It cannot be
regarded as a typical Essex species: indeed, it is surprising that this graceful butterfly, which is usually
associated with chalk downland, should occur in Essex at all, and that after a number of years of low
density existence it should still survive in its few Essex haunts which are restricted to the Rochford
Hundred It is for this reason, and not because it is a familiar sight in Essex, that it can claim notability.
We now turn to the moths and in their case we depart from the systematic order. As previously
mentioned, they have been selected for special mention for a variety of reasons, and it is convenient to
discuss them category by category.
Only one species of moth is entirely confined in Britain to Essex. This is an attractive and fairly
large noctuid which goes by the not particularly evocative name of Fisher's estuarine moth (Gortyna
borelii). This insect was discovered in Essex by J. B. Fisher (1971), after whom it is named It is
restricted to the shores and islands of Hamford Water in the extreme north-east where its larva feeds
in the stems of the sea hog's-fennel, an umbelliferous plant confined in Britain to this area and one
locality in Kent from which, however, the species is absent Since G. borelii was discovered, Hamford
Water has been much visited by collectors, some of whom, as well as collecting the flying insect, have
dug up the equally rare foodplant for the pupae, but fortunately the moth and the plant are well
protected over much of the area, including the Essex Naturalists' Trust's nature reserve on Skipper's
Island where both are well established It is of interest to mention that in Harwood (1903) mention is
made of a large, pale form of the frosted orange (G. flavago), apparently found nowhere else in Britain,
frequenting the area where G. borelii is now known to fly. As this description fits G. borelii reasonably
well, it seems that its presence but not its identity had been noted 70 years before Mr Fisher's
discovery.
The equally attractive but small and delicate Essex emerald (Thetidia smaragdaria) may now be
confined in Britain to one locality in Essex and another in Kent It is an interglacial relic and while
confined on this side of the North Sea to the coast of south-east England where the larva feeds
exclusively on sea-wormwood it is not restricted to the seaboard on the Continent It was discovered
in this country in 1826 at Southchurch near Southend-on-Sea (Curtis, 1830) and subsequently proved
to be fairly widespread around the estuaries from the River Colne south to the Thames. As one of
Britain's rarest insect species, T. smaragdaria is given special protection by the Wildlife and
Countryside Act 1981, and every effort is being made to conserve it Its decline has been attributed to
a number of factors, among them habitat destruction and disturbance resulting from coastal defence
works; herbicide spray-drift; overgrazing on sea-walls by cattle and horses; coastal pollution; and, on
occasion, overcollecting of larvae.
7