Sap-sucking bugs are to be used to try to kill an invasive plant which grows as fast as one metre a month and can damage buildings, drains, railways and roads.
Wildlife Minister Huw Irranca-Davies approved the release into the wild of a type of lice which is a predator to the knotweed plant in Japan.
The International Union for Conservation of Nature said knotweed is on a list of the 100 most invasive species in the world.
Controlling and clearing it in the UK costs around £150 million every year, according to the Government.
Knotweed also erodes river banks and other habitats and crowds out plants native to their areas.
A plant-hopping species of lice, a psyllid insect, may be a natural pest control for the plant as it it is thought the lice will only attack the knotweed and other related species.
Ian Nicholson, of the Institution of Civil Engineers, 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."
