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GLOW-WORMS
IN CUMBRIA
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If
you know of any recent sightings of Glow-worms in Cumbria
Peter
Wilde would be pleased to hear from you
on 01229 586737
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The
Glow-worm isn't a worm, but a beetle; females are wingless, however.
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Populations
are believed to have declined drastically in the last 50 years.
Cumbria has most of the populations of northern Britain; the species
is more widespread in Wales and southern England.
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In
Cumbria, the best sites are in the south of the county on limestone,
but records exist from the west (Ravenglass area), from around Carlisle
and from the CWT reserve at Barkbooth.
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All
stages of the life cycle emit some green light, but females generate
an intense glow to attract mates.
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The
best times to see glowing females is at dusk (10 - 11 p.m.) in late
June and July on warm humid nights.
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Females
are larger than males, so they can carry more eggs, but this means
that dispersal to new sites is difficult and populations have tended
to become increasingly isolated.
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Adults
do not feed much, but the larvae feed on snails, injecting digestive
juices into them. The larvae develop over three years, spending
two winters in hibernation.
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Glow-worms
are, therefore, most likely to be found on unimproved limestone
areas, railway embankments and church yards.
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The
last three abdominal segments of the female adult have a layer of
luciferin backed by a reflector of minute crystals. When oxygen
and moisture combine with luciferin, light is emitted; the effect
is controlled by switching on and off the supply of oxygen.
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