This story is about how a pair of tiny insects about 6mm long and their very hungry caterpillars can eat a large tree.
Ash trees are beautiful: young trees have smooth grey bark, whilst older trees have bark that cracks to form diamond shapes, like the pattern we see on a chain-link fence.
No one likes to see these wonderful trees cut down in their prime. One of the problems with ash dieback disease is that there is often little to see on the outside. Yet the tree is damaged on the inside.
Some beetles can bore into wood of infected trees, as the photograph shows. The beetles have made many round holes as well as carving the thin curved galleries in the wood of the tree.
It is hard to say what type of beetle caused this damage, but one likely culprit is the oak pinhole borer, which (despite its name) can attack weakened ash trees. The infection probably occurred during the summer months, when a male digs a hole a few centimetres deep in the bark of the tree.. The female inspects the hole and then returns to the surface to mate with the male.
The female then re-enters the hole and the male follows her in. She digs deeper into the tunnel, working in a curve. The female eats the wood and excretes the fine wood fragments in her feces. This is called frass. The males help to keep the tunnels clear, by moving the grass out of the way.
The insects’ bodies are covered in spores of a group of fungi, called ambrosia fungi.
These fungi grow in the galleries made by the female. The eggs of the insects hatch to form larvae, which feed on the ambrosia fungi.
The round holes are part of the tunnels that reach the surface of the wood, allowing the new adult borers to leave the tree.
It is an interesting relationship between the insects and the fungi, because both depend on each other for their survival.
We talk in these stories about how energy flows through ecosy stems and how atoms are recycled by other organisms. The ash tree, the ash dieback fungus, the beetles and the ambrosia fungi are component parts of an ecosystem.
Explain how energy flows through the ecosystem and how atoms are reused.
These fruits are blackberries. The seeds are found inside the berries. They are tiny, with hard tough seed coats.
Winter has come to Nowhere Wood and ice has formed around the fallen trees in the pond. Everything shivers and wood is silent again. Squirrels search for food in the frozen mud, but everything else is waiting, biding its time.
Silent, except for an ancient overgrown hedge formed from a row of old trees, bound together into a thicket by generations of bramble stems. These trees are singing, for this is the home of the tree sparrows. The trees are just outside the wood, next to a path much used by dogs taking their owners for a daily walk.
The tree sparrows are warm, protected from the icy wind by the layers of dead branches that surround them. Impenetrable, they are hidden amongst the branches, out of harm’s way. In this forgotten place, they thrive and they sing.
Mushrooms are fruiting bodies. They produce thousands of tiny spores.
