Transect monitoring of Glow-worm Lampyris noctiluca
(Coleoptera: Lampyridae) colonies in Essex
TIM GARDINER & MICHELLE PYE
Centre for Environment & Rural Affairs (CERA),
Writtle College, Lordship Road, Writtle, Chelmsford, Essex, CM1 3RR
Introduction
In Essex, the Glow-worm Lampyris noctiluca was described as rather rare (Corke 1984) although
it was recognised that this species was under-recorded in the county. To rectify this research
deficit, the 2001 Essex Glow-worm survey was initiated with the aim of involving the public in a
search for undiscovered colonies and to start transect counting at sites with a known L. noctiluca
colony. The results from the first two years of the survey are reported in Gardiner et al. (2002,
2003a, 2003b). Gardiner et al. (2003a) showed that the future of this species was uncertain in the
county due to low counts of glowing females at many transect sites. Furthermore many sites were
isolated by several kilometres from the next nearest occupied site and are paiticularly at risk of
extinction from the county. Transect monitoring of adult females has been conducted for three
years at nine study sites in Essex, and it is the aim of this paper to present the results of these counts
and discuss the implications for the conservation of L. noctiluca in the county.
Method
Sampling of Lampyris noctiluca populations
A transect was established at each of nine sites (Table 1) with a known L. noctiluca colony in 2001
to allow the abundance of glowing adult females to be ascertained. Habitats recorded at the transect
sites included ancient woodland, unimproved meadow and scrubland. Each transect was at least
100m in length and was walked once in each of three two-week periods: 9-22 July, 23 July-5
August, and 6-19 August in 2001, 2002 and 2003. Any glowing adult females that were observed
along the route were recorded. It was felt that these three periods adequately incorporated the peak
glowing season in Essex when most adult females will be displaying.
Table 1. Characteristics of the 9 transect sites in Essex (range in brackets)
The walks were standardised so that comparisons could be made between the density of females
per 100m at different sites. 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. Surveys were not
Essex Naturalist (New Series) 21 (2004)
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