Download Meeting Stag Beetles

Meeting
Stag Beetles
(Key Stage 2)
Deborah Harvey
The stag beetle’s life cycle
The stag beetle, or Lucanus cervus to give it its proper scientific name, is Britain’s largest
terrestrial or land-living beetle. It is also sometimes known as a thunder beetle, or a
“Billywitch”.
Many of us know what the male looks like with its large antlers and chestnut colour, but
what not so many people know is that the numbers of stag beetles are falling.
We are not sure why the numbers are falling but probably it is because of changes in
climate and the fact that people no longer leave rotting wood around, an essential part of
the life cycle of the stag beetle.
Stag beetle eggs
Eggs are laid by the female in or near rotting
wood in late summer. They are about 3mm
long. They hatch out 2-3 weeks later as tiny
larvae.
Stag beetle larva (or grub)
The stag beetle larva is cream with an orange
head and orange legs (3 pairs like the adult),
and has small brown antlers. It lives in rotten
wood, which it eats. It takes up to 6 years to
reach full size (approx. 8 cm), shedding its skin
five times as it grows.
Pupa
After 6 years, the larva leaves the wood and
makes a ‘cocoon’ in the soil. Next it turns
into a pupa. This happens in late summer or
autumn and lasts a few weeks.
Then the fully grown beetle emerges but it
stays under the ground until the next summer
when it comes out as an adult.
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Male stag beetle
The fully grown male stag beetle flies in the
evening, looking for a mate. It is up to 75mm
long, including its antlers. It does not need to
eat, but may feed on sap (the sticky stuff that
runs down the sides of trees).
Female stag beetle
The female stag beetle is smaller than the
male (up to 55mm). She is often seen on the
ground looking for somewhere to lay her
eggs. She lays them in or near rotten wood
then dies shortly afterwards.
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How do we know the stag beetle is an insect?
Like all insects the adult stag beetle has three body parts: a head, a thorax, and an
abdomen.
The head of the male has large jaws or mandibles. These are used for fighting with other
males and for attracting a mate. The stag beetle also uses his jaws to protect himself if
he feels threatened. But his mandibles are very big compared to his head and the muscles
that move them aren’t very strong and so he can’t bite very hard. The female with her tiny
mandibles can bite much harder.
The thorax, or middle bit, is joined on to the head and has the three pairs of legs attached.
All insects have 3 pairs of legs joined to the thorax. At the end of their legs they have little
hooks to help them grip on to things.
Below the thorax is the abdomen. In the female the eggs will be stored here before they
are laid. This is also where the wings are. The stag beetle has two pairs of wings, like all
insects. The top pair, known as wing cases, is hard and shiny. When the stag beetle flies it
holds the wing cases up and unfolds the soft wings underneath. These look like very big fly
wings.
A male stag beetle looks a bit like a helicopter when it flies because it flies upright with its
large black wings held behind it. It is also very noisy. But it doesn’t fly towards people to
attack them, and it does not scare them on purpose.
How does a stag beetle breathe?
Stag beetles (and other insects) have little holes down each side of their bodies called
spiracles, which lead to trachea. Just like people, insects need to take in oxygen and let
out carbon dioxide. The spiracles have valves which the insect can open and close, to allow
gases in and out.
Do stag beetles grow?
No they don’t. Just like all adults they have stopped growing. If you find a little stag beetle
it won’t grow into a big one. It did all of its growing when it was a larva. As the larva
grows it has different stages called instars. At the end of each stage the larva loses its old
skin.
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How does a stag beetle eat?
A stag beetle larva feeds by chewing the wood it lives in, using its jaws. Stag beetles only
feed on dead wood and they don’t kill trees. Adult beetles don’t need to eat at all as the
larva has built up a fat store during its development. However, they can eat the sticky sap
that runs down the side of trees and some people think that they can make holes in trees
to let the sap out. They lick the sap from the trees with their orange tongues. They don’t
use their large antlers to eat with, and they don’t eat other insects.
GLOSSARY
Spiracle
A hole in the skin of an animal to allow air to pass in and out.
Trachea
An airway in an animal.
Valve
A movable part that controls the flow of a gas or a liquid.
Instar
A stage of development of a growing insect. Because insects have their skeletons on the
outside of their bodies, they have to shed their skin at each stag.
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Making a safe habitat for the stag beetle
Late in the summer the female stag beetle buries herself under the ground near some
rotten wood and lays her eggs. So how can you encourage stag beetles to breed?
You can…
• leave any old tree stumps in the ground
• leave wood piles in your garden
• or build a special wood pile for the stag beetles. You can do this by digging a hole about
60cm deep, and putting wood, or rotting wood, into it so that the wood sticks up out of
the ground. Then you just leave it alone and hopefully stag beetles will use it!
Once you’ve built your log pile try not to disturb it, and encourage your friends and
relatives to leave wood and woodpiles in their gardens.
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Stagbeetle Friendly Gardening
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Guidance for teachers
This resource is intended for use by children in years 4 through 6, but could easily be
adapted for children of any age. It can be used in conjunction with our other resource
packs – Insect Restaurants, 3D Bug Art, and Meeting Stag Beetles (Key Stage 3).
National Curriculum links
Science, Life processes and living things, section 5 Living things in their environment –
learning about the adaptation of plants and animals to their habitat, and about ways in
which living things and the environment need protection.
Ideas for further work
http://www.stagbeetlehelpline.co.uk gives lots of information on stag beetles,
including instructions on “Burying a bucket for beetles”. This is a way to create a suitable
habitat for stag beetles on a small scale, developed by Deborah Harvey at Royal Holloway,
funded by the People’s Trust for Endangered Species.
http://www.waddesdon.org.uk/explorer_trail/files/teachers%20science%20pack.
pdf shows how to build a “bug hotel” to attract a wide variety of insects to a garden.
http://www.bbsrc.ac.uk/society/schools/primary/real_bugs/real_bugs_1_22.pdf
is a pack designed for use in primary schools with children in Key Stages 1 and 2, including
guidance on collecting minibeasts safely, minibeast identification sheets, and enlargements
of insect mouthparts.
http://ptes.org/ gives you more information about the People’s Trust for Endangered
Species, the organisation that funded much of Royal Holloway’s research into stag beetles.
There are some pages for kids.
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Royal Holloway, University of London
Egham, Surrey, TW20 0EX
T: 01784 434455
www.rhul.ac.uk
5539 06/09