Researchers looking for ways to eradicate toxic cane toads have found a way to trap them using ultra-violet "disco" lights.

Introduced from Hawaii in 1935, the pests are now an environmental menace, spreading in the millions across Australia's tropical north. Cane toads, some as big as dinner plates, can even kill crocodiles and wild dogs with their hallucinogenic venom.

Australian scientists have tried for four decades to find a way to eradicate them, with only limited success.

Researchers in the Northern Territory found that the "disco lights" are a great way to attract cane toads so that they can be trapped.

After experimenting with red and then blue lights, Australia's Frogwatch "Toad Buster" project found that the "black" light was the most effective way to attract them.

Frogwatch coordinator Graham Sawyer says, "We've found that the old toads are definitely a disco animal."

He says 200 of the toads were caught in a three-week project using the disco lights at a remote station about 120 km (75 miles) south of the Northern Territory capital, Darwin.

Sawyer adds, about 1,500 toads had been trapped since January.