BBC Knowledge June 2017

(Jeff_L) #1
Love and wood
But stag beetles also have an army of dedicated fans.
Richard tells me about the ‘Willy the stag beetle’
stories his father made up for him and his siblings,
and about chasing one “flying like a model aeroplane”
through the streets of Bromley as a young adult.
“They’re so majestic,” he says, as he sifts through
his drawer of stag beetle body parts.
Another stag beetle hotspot is Colchester in Essex,
where Maria Fremlin, a retired lab technician, has
dedicated the past 15 years to studying them in loving
detail. As well as creating habitats for the beetles
in her garden, Maria has reared them in a terrarium
in her garage, filmed them, monitored local
populations and written a clutch of research papers.
“All they need is love and wood,” she says.
Deborah Harvey of the University of London has
herself been studying stag beetles for more than

a decade. “It’s difficult to know how many there are
because this is mainly a garden species in Britain,”
she explains. “You can’t just wander into people’s
backyards to count beetles.”
Deborah collaborates with the People’s Trust for
Endangered Species (PTES) and assisted its ‘Bury
Buckets 4 Beetles’ project, which has encouraged
gardeners to create artificial egg-laying sites.
More than 1,000 beetle buckets have been buried
since 2005, with about a quarter attracting residents.
One example of behaviour that helps Deborah
find the larvae is stridulation. This is believed to be
a form of communication, and involves a grub rubbing
its second and third legs together. “They don’t
like being too far apart, so they stridulate to check
the whereabouts of the others,” she explains.
“We can now simply bury sensitive microphones
in the soil to determine where larval populations are,

ILLUSTRATION BY DAN COLE/THE ART AGENCY

4 ADULT 9 months in
soil; a few weeks above ground
In autumn, the adult crawls out
from its cocoon, but stays in
the soil until May or June.
Males appear first to set up
territories; most will be dead by
mid-July, but, in some years,
1 EGG 3 weeks all beetles die in June.
After mating, the female digs into soil
near buried decaying wood, often
where she developed as a larva.
She lays her small eggs about 30cm
down, then dies soon after. Three
weeks later, the larvae hatch.

3 LARVA 3 to 7 years
The grubs are C-shaped, cream-coloured
and sightless, with a rigid head and sharp
pincers for munching wood. They live in
both wood and soil, taking between three
and seven years to pass through three
instars (larval stages), moulting between
each one. Finally, they bury themselves
in the soil and create a cocoon.

2 COCOON 3 weeks
Each oval-shaped cocoon can be as
large as an orange. Inside, the larva
pupates and metamorphoses into
an adult. Usually this takes about three
weeks in late summer; in a hot year,
though, the change is faster, and, in
cooler conditions, it can take longer.

June 2017 71

Stag


beetles


From Egg to AdultSTAG BEETLE LIFE-CYCLE

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