City of Regina using beetles to curb spread of highly invasive purple loosestrife plant

The City of Regina has recruited a small but mighty legion to slow down the spread of noxious weeds.

Galerucella calmariensis — a type of beetle — feasts on purple loosestrife, a highly invasive plant that's growing throughout the city and along Wascana Creek.

Russel Eirich, manager of open space services with the city, said purple loosestrife was brought to North America from Europe because people thought it would be a nice flower for their yard.

However, seeds from the plant can get into sewer systems and start growing in creeks and other bodies of water.

"They're a very invasive plant. There isn't, sort of, a natural predator here in North America, so it just disrupts the cat tails and starts to interfere with waterfowl and that sort of thing," Eirich told CBC Radio's The Morning Edition.

The city has released about 5,000 beetles that feed on the plant to help stop its spread.

Eirich said the beetles were initially released last year at the pond in Lakewood Park. That showed promising results, so the city decided to release more.

He said one of the reasons the beetles are effective is because they're very particular about what they eat, meaning they will stick to the purple loosestrife.

"That's the advantage of using biologicals like this," he said.

Beetles introduced to Canada in 1992

The beetles are brought in from Manitoba, according to Eirich, and were first introduced in Canada in 1992.

"It is now part of the Canadian ecosystem, has been part of the Canadian ecosystem for about 30 years now," he said when asked about using a non-native insect to deal with a non-native plant.

"We're only moving the beetles within Canada, so I wouldn't say that we're changing things up too much anymore."

The city has also released spurge beetles to curb the spread of leafy spurge weed, he said.

The city usually also releases ladybugs to deal with aphids, but Eirich said the usual supplier wasn't able to provide them this year. Instead, the city will look at ways of ensuring the ladybugs that are already in the city can survive the winter.