Lara Giddings, the attorney general for the island state of Tasmania, said the kangaroo-like marsupials were getting into poppy fields grown for medicine.
She was reporting to a parliamentary hearing on security for poppy crops.
"The one interesting bit that I found recently in one of my briefs on the poppy industry was that we have a problem with wallabies entering poppy fields, getting as high as a kite and going around in circles," Lara Giddings told the hearing.
"Then they crash," she added. "We see crop circles in the poppy industry from wallabies that are high."

http://news.bbc.co.uk/2/hi/asia-pacific/8118257.stm