WINNIPEG -- An invasive beetle that has already ravaged millions of trees in Central Canada and the U.S. has made its first appearance in the West.

The emerald ash borer, a highly efficient killer of ash trees, has been found in a tree in the Winnipeg neighbourhood of St. Boniface.

Holes in the tree suggest larvae from the bugs have already hatched and flown off -- most probably infesting other ash trees.

Scientists say the borers eventually kill all the ash in a stand and there's no way to stop them.

Federal officials are trying to determine how far the infestation has spread in Winnipeg, which has 350,000 ash trees.

City forester Martha Barwinsky says the city will be able to mitigate the damage, but warns the city's forest cover will change.