The Government today approved the release of an imported bug which, it is hope, will attack on the biggest scourges affecting Britain’s waterways: the massively invasive Japanese knotweed.

The weed, which has pretty pink and white flowers, was introduced to Britain as a garden specimen but soon escaped and began to grow like wildfire along thousands of miles of river bank.

In doing so, it killed off many native species like reeds and bulrushes, which are home to some nesting birds but also a breeding ground for millions of insects. These, in turn, act as food for fish and waterside birds like wagtails and bank martins.

The Japanese bug, a moth-like creature called a psyllid, lays eggs on the knotweed and its larvae feed on the plant, sucking out its sap. Knotweed which is so strong that it can grow through concrete is estimated to cause over £150milion of damage in the UK every year.