Glow-worms Lampyris noctiluca L (Coleoptera: Lampyridae) in Essex
the Essex Wildlife Trust website and the British Glow-worm page www.glowworms.org.uk.
Although the survey, therefore, involved participants with limited or no entomological knowledge,
the distinctive nature of the adult females minimised the likelihood of identification difficulties.
With appropriate guidance, survey participants were asked to select a suitable site at which to
establish a transect route, either within an area where L. noctiluca had been observed before or at
a new location where habitats such as unimproved grassland were present. Survey participants
were initially required to visit their site during daylight hours to determine the transect route, to
produce a sketch map of the area and to note habitat types and management regimes.
A transect of at least 100 metres in length was walked during each of three pre-determined fortnightly
periods (Table 1) and any glowing females which were observed along the route were recorded. It
was felt that these three periods adequately incorporated the peak glowing season. Survey
participants were required to commence each walk between 2200 and 2300 hours, and to terminate
by 0000 hours. A slow strolling pace was recommended for the walks to reduce the risk of
overlooking glowing females along the route. During the transect walks, survey participants were
asked to record the habitat types which were utilised by the glowing females, to detail any artificial
lighting at the site and also to mark the approximate position of any L. noctiluca individuals on the
sketch map. If glowing females were not observed during the first two transect walks, survey
participants were advised to abandon the final walk. This transect method was devised to standardise
the results obtained and to facilitate site comparison.
Table 1. Two week periods for each of the three transect walks
Results
Recording coverage
Figure 1 displays the distribution of tetrads surveyed in 2001, which includes both the transect
monitoring and the casual surveys. The survey attained quite widespread coverage of the county,
although there was a slight bias towards the Chelmsford area, where the survey organisers were
situated. There were fewer surveyors in the north and west of the county, and also in the extreme
south near Grays. A total of 48 people took part, with many surveying more than one site. Overall,
57 locations were visited by survey participants and transect walks were completed at 35 of these
sites.
Distribution of L, noctiluca in Essex
The survey illustrates that L. noctiluca is widespread but localised in Essex (Fig. 2). This species
occurs scattered throughout most of Essex, although there are very few records for the north and
west of the county. L. noctiluca has been recorded at 43 sites since 1992 and was observed at 28
sites in 2001. There have been many colonies recorded on Danbury Ridge (five sites), around
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Essex Naturalist (New Series) 19 (2002)