Glow-worms Lampyris noctiluca L (Coleoptera: Lampyridae) in Essex
have decreased since the early 1900s. Additionally, air pollution from London may have
detrimentally affected colonies within this area because snails can accumulate chemicals deposited
onto vegetation and L. noctiluca individuals could subsequently become exposed to these pollutants
(Tyler 1994).
The majority of L. noctiluca colonies that were observed during the 2001 survey were found on
nature reserves and in other areas with no artificial lighting (Tables 2 and 3). The intensification of
agriculture since the 1950s, coupled with the inappropriate management of rural roadside verges
may have resulted in the loss of many colonies in the wider countryside. Development is now the
predominant threat to colonies which occur outside of nature reserves. This problem is compounded
by the lack of any legal protection for this species. Colonies within the vicinity of Grays and the
Braintree Freeport complex are particularly threatened and several favourable sites have been
destroyed in these areas during the last few years. Scrub encroachment is probably the main threat
to colonies which occur on nature reserves. Although scrub is an important habitat for L. noctiluca
in Essex, encroachment must be carefully controlled because colonies are infrequently found within
mature woodland.
Streetlights were only present at one site where L. noctiluca were observed, probably because
artificial lighting is known to distract flying males when they are searching for glowing females
(Tyler 2002). Any attempt to erect new streetlights near to a known colony must therefore be
opposed where pedestrian safety is not a major issue.
Conservation
L. noctiluca appears to be under no immediate threat from extinction in Essex, although many of
the colonics which exist arc isolated and most arc relatively small. Protection of the remaining
populations which occur outside of nature reserves is a priority and where development is planned
for a site that currently supports a colony, the planning proposals should be opposed. It is intended
that this survey will continue in future years in an effort to detect more new colonies. There are still
many old records to be investigated in areas such as Thorndon Park and Wrabness Woods. Surveys
should also be conducted in the north and west of the county where there are very few records for
this species.
Transect monitoring
The transect monitoring that occurred during the survey provided valuable data on the abundance
of L. noctiluca at different sites. It is important that these transect walks are undertaken in future
years using exactly the same methodology so that the progress of L. noctiluca in Essex can be
ascertained. This monitoring will detect the long-term trends in the abundance of L. noctiluca and
will determine whether future research or conservation measures need to be implemented. These
walks will enable the effectiveness of the current conservation management strategies to be
ascertained and altered if necessary.
Site management
Little is known about how to manage sites to encourage L. noctiluca (Tyler 2002). Alexander
(1992) states that the main objective of management for L. noctiluca should be to maintain vegetation
structure and snail populations. Where possible, the available L. noctiluca habitat should be extended
in an effort to link it to other favourable areas. The use of chemicals, especially Molluscicides,
should be avoided as they have detrimental impacts upon snail fauna. Patches of scrub and dead
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Essex Naturalist (New Series) 19 (2002)