Filling the gaps in your bug mansion:

• Dead wood. Dead wood is an increasingly rare habitat and is essential for the larvae of wood-boring beetles. It also supports many fungi, which help to break down the woody material. Crevices under the bark hold centipedes and woodlice.
• Hollow stems. Hollow stems, such as old bamboo canes, or holes drilled into blocks of wood, make good nesting sites for solitary bees.
• Stones and tiles. Amphibians need a frost-free place to spend the winter. Provide stones and tiles in the centre of your habitat to give amphibians the cool, damp conditions they need.
• Straw and hay. These provide many opportunities for invertebrates to burrow in and find safe hibernation sites.
• Dry Leaves. Dry leaves offer homes for a variety of invertebrates by mimicking the litter on the forest floor.
• Loose bark. Beetles, centipedes, spiders and woodlice all lurk beneath decaying wood and bark.
• Corrugated cardboard. Roll up a piece of corrugated cardboard and put it in a waterproof cylinder to create a home for lacewings.
• Dry sticks. Dry sticks are perfect for ladybirds to hibernate in.
• Nectar-producing plants. Plant some nectar-rich flowers in and around your new bug mansion to prvide food for butterflies and bees.