The insect, which is a predator of the plant in Japan, will act as a natural form of pest control. Defra says this is the first time that a solution like this has been used to help control the spread of a non-native invasive plant in Europe. Psyllid is commonly known as ‘jumping plant lice'.

Irranca-Davies said: "Japanese Knotweed causes over £150 million worth of damage and disruption throughout the UK every year.  This project is not only ground-breaking, it offers real hope that we can redress the balance. These tiny insects, which naturally prey on Japanese Knotweed, will help free local authorities and industry from the huge cost of treating and killing this devastating plant."

Chair of Environment and Sustainability expert panel at the Institution of Civil Engineers (ICE) Ian Nicholson said:

"Japanese Knotweed is a big issue for the construction industry, costing millions of pounds each year to manage. The ICE therefore welcomes any advances in providing solutions to this invasive species, provided of course they do not produce any other negative impacts on the environment."

Scientific research body CABI has tested in the UK on over 90 types plants, focussing on closely related native species as well as important crops and ornamental species to ensure it does not attack other plants.  If the first phase is successful, the psyllid will be released at further sites where it will continue to be monitored.

CABI lead researcher Dr Dick Shaw said: "This is a great opportunity for the UK to benefit from a technique commonly used outside Europe.  We have every reason to believe that this knotweed specialist can help limit the impacts of this harmful invasive weed safely and sustainably."

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