A drug found in the fungus is "a good starting point for novel cancer medicines", a scientist says.

The webbing can be found on trees in St George's park in Bristol.

Box tree caterpillars are the larvae of a moth that feeds on box plants.

Fewer caterpillars means fewer "beautiful, charismatic butterflies", a researcher says.

The Forestry Commission say the caterpillars and their nests contain hairs which can cause rashes.

The Norfolk Wildlife Trust says they are likely to be a type of micro ermine moth caterpillar.

The vast expanse of webs are down to a "caterpillar population explosion", an expert says.

The web in South Yorkshire is described by one expert as a "very impressive infestation".