The species continued to decline during this period, so that by the mid 1970s fears
were being expressed as to its impending extinction. Out of a total of some thirty 10 km.
squares, mainly in south and east England, from which L. dryas had previously been
recorded, the species was reported from a mere eight between 1961 and 1979 (Chelmick,
1979). Two of these were from Essex localities. C. O. Hammond (1977) described it as
'now becoming very scarce', having 'disappeared from several of its old localities near
London through pollution of the habitat'. Indeed, this turned out to be something of an
understatement, as a subsequent publication by the Nature Conservancy Council
declared it probably extinct (Chelmick et al.. 1980).
In view of the concern felt about the fate of L. dryas, N. W. Moore carried out. in 1978, a
survey often previous English sites for the species, as well as searching suitable habitats
in the Cambridgeshire Fens, and carrying out a widespread search in the south and west
of Ireland. Though the species continued to exist in a small number of Irish localities, it
was no longer present in any of the English ones. (Unfortunately, none of the sites
visited was in Essex.) Moore attributed the catastrophic decline of L. dryas to a
combination of three factors: loss of habitat (due to agricultural reclamation, pollution,
etc.). periods of drought, and small population numbers. In England. L. dryas is
associated primarily (but not exclusively) with ditches and ponds on low-lying alluvial
land near the sea. Sometimes it occurs in brackish water, and always in sites with
plentiful emergent vegetation. Moore gives Water Horsetail. Reed-mace and. in Ireland.
Bulrush as plant-associations for the species. Since these typical sites are transitory,
representing final stages in the drying out of the aquatic habitat, the survival of the
species is dependent on its ability to re-colonise new sites. If the process of drying out is
accelerated by drought, with population sizes in any case low. and adjacent sites
destroyed or altered by human activity, then chances of re-colonisation are slim (for a
more detailed account, see Moore. 1980).
In the context of this pessimism regarding L. dryas there was great excitement at the
news that the species had been re-discovered by a group including K. M. Rowland and
R. G. Payne on 23rd June. 1983. The site was on M.o.D. land in the extreme south-east of
Essex, in a ditch almost choked with Sea Club-rush. Other rushes. Common Reed and
Water Crowfoot were among the other plants present. Other sites were soon discovered
in the same area and another in Kent. Then, on 19th July, another site for L. dryas was
discovered on M.o.D. land south of Colchester by a small group from the C.N.H.S.
including myself. Upwards of a dozen individuals were seen and photographed as they
settled low down in vegetation or made short flights in the vicinity of the brackish poo]
and adjacent borrow dyke where they were found. As with the south Essex sites, the
dominant plant in the habitat was Sea Club-rush. In addition, the open water of the
pool contained Fennel Pondweed.
The rediscovery of L. dryas in several quite widely separate sites in a single season
after more than ten years without records anywhere in England posed the question
whether this was evidence of a sudden influx of migrants, or. whether, indeed, the
species had simply been overlooked. Accordingly, in 1984. considerable interest
focused on attempts to confirm the continued presence of the species at the 1983 sites
and to investigate further possible sites. Happily, visits to the north-east Essex site
between 27th and 29th June. 1984 con firmed the continued presence of the species there
and in very considerable numbers. Subsequent visits by K. M. Rowland and R.(i. Payne
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