Five years after thousands of Japanese bugs were released into Britain to control the spread of a superweed, scientists say more time is needed to assess whether the ambitious project will succeed.
The psyllids — Aphalara itadori — were reared in laboratories from a sample brought over from their native habitat in Japan where they suck the sap from Japanese knotweed and keep the plant in check, along with a range of other bugs.
In Britain, there is no natural enemy to knotweed and, as a result, the invasive plants have gotten out of control in some areas.