Meeting Stag Beetles (Key Stage 2)

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 scientifi c 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 fi ve 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. 1 Male stag beetle The fully grown male stag beetle fl ies 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. 2 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 fi ghting 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 fl ies it holds the wing cases up and unfolds the soft wings underneath. These look like very big fl y wings. A male stag beetle looks a bit like a helicopter when it fl ies because it fl ies upright with its large black wings held behind it. It is also very noisy. But it doesn’t fl y 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 fi nd 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. 3 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 fl ow 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. 4 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. 5 Stagbeetle Friendly Gardening 6 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/fi les/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 identifi cation 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. 7 Royal Holloway, University of London Egham, Surrey, TW20 0EX T: 01784 434455 www.rhul.ac.uk 5539 06/09.

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