Ask what are the needs of an animal to stay alive? (food, water, air, shelter).
Show a real wood bug. Ask if students have seen them before in parks or gardens.
Class discussion of the needs of wood bugs, based on students' knowledge or observation of wood bugs in their natural environment (wood bugs are often found in the fall or spring under logs and rocks in gardens and forests).
Build or show a habitat which satisfies the needs of wood bugs:
A chunk of rotting wood or bark provides shelter underneath it, as well as some food.
The habitat can be opened briefly each day to exchange the air.
A layer of damp sand keeps the air moist. Wood bugs do not like puddles, but they need a damp environment. Keep the sand damp (but not soggy - it is easy to make it too wet). Sprinkle drying sand with dechlorinated water (tap water let to sit for a couple of days).
Food is vegetables (they love potato), also fresh leaves such as lettuce, and optionally some partway rotted leaves. Remove any food that becomes mouldy.
Store the habitat in the coolest area of the classroom.
Add wood bugs to the habitat from a walk, previous experiments, or from a collection made by the teacher in advance.
Extended discussion ideas:
Wood bugs’ food is mostly rotting vegetation, but they do not like to be too wet, so wood bugs are often found in the upper layer of a compost heap.
Wood bugs are decomposers and eat dead plants (as well as some live ones). Decomposers are a crucial part of the cycle of life on earth. They eat up rotting things, and their poop ("faeces") is soil! So they clear the ground of dead things and make soil for plants to grow in.
Wood bugs need water to drink, as do all living things. They also need water in the air from which they obtain their oxygen (they do not breathe oxygen gas as we do). Wood bugs evolved from, and are closely related to, shrimp-like marine organisms. (The first woodlice were marine isopods which are thought to have colonised land in the Carboniferous period.) Like the ocean animals they are related to, they have gills! They use their gills to extract oxygen from water. Because of this, they always need to be in a moist environment, and will die fast if they dry out.
For shelter, wood bugs like to live in moist (but not soggy) dark places, such as under paving stones, rocks and chunks of rotting wood.
See reference for more information and different kinds of wood bugs: http://en.wikipedia.org/wiki/Woodbug. I believe I collected wood bugs from these three families: Oniscidae, Porcellionidae and Armadillidiidae (pill bugs, which roll into a ball).
Students take care of their wood bug habitat. Take the lid off periodically to make sure there is enough oxygen in the container. Remove any food that mould grows on. The habitat needs to be moist but not soggy. A habitat can be kept for just a week, or several weeks. If kept for several weeks, babies may be born in the habitat. Do not pick up the wood bugs with fingers as they are very delicate. Use a paintbrush if you need to move them around.
Look for evidence of the wood bugs eating (food with nibbles out of it), excreting (brown spots of faeces), growing (a shedded exoskeleton), having babies (new baby wood bugs; the eggs are too small to see with the naked eye).
When the habitat is ready to be dismantled (usually after a couple of weeks, maybe a month if the classroom is cool), they need to put back where they came from (choose a non-frosty day - spring and fall are when wood bugs are not hibernating, so the best time). Could be combined with a decomposer hunt activity.
Students use a paintbrush to flick the wood bugs from their habitat into a garden or sheltered spot.
