which would have been emerging as adults in 2002,
drowned.The 2002 ‘season’ for adult stag beetles was a disappointment. Low numbers were reported from across its range in Suffolk. The number of recorded sightings from stag beetle hotspots in other counties was also low. Several factors, which could account, in part, for the reduction in numbers are suggested below.
In 1997, a cold wet June affected the emergence of adults. Fewer adults than is usual were reported by observers across Suffolk. It is therefore possible that fewer eggs were laid in 1997. Eggs laid in 1997 are likely to have developed into the adults due to emerge in 2002.
The
year 2000 was the wettest in the region since 1916. February 2001 was the
wettest for 85 years and the sixth successive month with rainfall above the longterm
average. The prolonged excessive rain from October 2000 onwards to well into
2001 caused the soil to become saturated and waterlogged. As a result it is
probable that many larvae, which would have been emerging as adults in 2002,
drowned.
The weather for much of the emergence period in 2002 was cold, wet and very windy. Conditions were perfect for stag beetle flight at dusk on only a few occasions.
Pitfall and aerial trapping trials were carried out in Bentley, Suffolk, to try and establish a satisfactory method for estimating stag beetle numbers. There was limited success when using either male stag beetle pheromone or live beetles as an attractant.
Rotting wood proved to be a better lure. Further work using attractants is planned for 2003.
Counting beetles found squashed on the road has again proved
to be a successful method for determining:
Counts carried out in 2002 confirm previous findings (Hawes 1998, 2000), i.e. females are three times more likely to be killed on the roads than males.
Investigations were carried out by the author to try to determine the beetles’ response to external environmental factors, such as light, humidity and gravity. This work was severely limited due to the small number of live stag beetles available. The investigations will be continued next year.
Larvae are being kept in friable, decaying elm wood to observe their growth.
Different food materials are being offered to these grubs in experiments designed to determine their responses.
If anyone accidentally digs up larvae, it is best to re-bury them in the decaying material from which they were removed. Where this is not possible, please contact the author.
The four boxes, full of decaying sawdust from broadleaved trees, sited at different locations in Suffolk during 2000, are being examined annually for the presence of stag beetle larvae.
The work on stag beetles described above is taking place in parallel with, and complements that which Deborah Harvey is undertaking at Royal Holloway College, London, where she is researching the fungal components of the rotting wood on which stag beetle larvae feed, and the response of the beetle’s antennae and its other chemoreceptors to various chemical stimuli.
The author gratefully acknowledges the support received from the Suffolk Naturalists’ Society and thanks the Society for the award of a Rivis bursary to help with this research. I am indebted also to Deborah Harvey (Royal Holloway College, University of London) and Mark Gillingham (Suffolk College) for their help with equipment and chemicals. Thanks are also due to the landowners in Bentley who allowed me to place traps in their gardens or orchards and visit these twice daily over a period of several weeks. Last, but by no means least, I am grateful to all those who contributed their records of stag beetle sightings and larval discoveries, either directly to me, or to the Suffolk Biological Records Centre.
(Suffolk records of the beetle sent to the People’s Trust for Endangered Species for their 2002 National Survey will be available to me when their database is completed).
All sightings of the beetle and observations of its behaviour are useful. Please send any records that you may have to the postal or e-mail address given below. Where possible, please give: the sex of the insect, if known; the name of the place where it was seen, e.g. Engry Wood, Bentley (grid reference preferable, e.g. TM 109381) and the day, month and year of the record. Historical records are also required.
Hawes, C. J. (1998). The stag beetle, Lucanus cervus L. (Coleoptera: Lucanidae) in Suffolk – a first report. Trans. Suffolk Nat. Soc. 34:35-49.
Hawes, C, J. (2000). Stag beetles 2000. White Admiral 47:34
Colin Hawes
3 Silver Leys, Bentley, Ipswich IP9 2BS
E-mail: colinjhawes@btopenworld.com
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