The mystery of crop circles in poppy fields in Australia's southern island state of Tasmania has been solved -- stoned wallabies are eating the poppy heads and hopping around in circles.

"We have a problem with wallabies entering poppy fields, getting as high as a kite and going around in circles," the state's top lawmaker Lara Giddings told local media on Thursday.

"Then they crash. We see crop circles in the poppy industry from wallabies that are high," she said.

Many people believe crop circles that mysteriously appear in fields around the world are created by aliens.

Poppy producer Tasmanian Alkaloids said livestock which ate the poppies were known to "act weird" -- including deer and sheep in the state's highlands.

"There have been many stories about sheep that have eaten some of the poppies after harvesting and they all walk around in circles," said field operations manager Rick Rockliff.

Australia produces about 50 percent of the world's raw material for morphine and related opiates.