The City of Montreal has been testing out a new method of hauling trees infected by the emerald ash borer out of Mount Royal park — one that harkens back to days of old.

Until the end of the week, two Belgian draft horses from Brisco stables in Prévost, Que., will be pulling infected trees out of the woods.

The city opted to try using horses instead of heavy equipment to hack down and remove infected trees in hard-to-access wetlands and marshy areas, where the impact of bringing in machinery would be significant.

Around 4,000 ash trees need to come down in Mount Royal Park before March 2019. (Radio-Canada)

"The horse is an additional tool that we can use to operate in certain areas, for example the wetlands. If we want to have zero risk of spilling oil or gas, then the horse can replace the machine," explained Luc St-Hilaire, a forestry engineer with the city's large park service.

There are more than 10,000 ash trees in Mount Royal park, two-thirds of which have been treated against the invasive bug. The rest will be axed by March 2019.

The two horses work alternate hours and take breaks in an on site shelter. (Radio-Canada)

The city announced that plan in January, saying that it would remove the dead trees and plant 40,000 saplings in their place.

Emerald ash borers are beetles that infest ash trees and eat them from the inside. They have been causing havoc on the island for several years, from Beaconsfield to Pointe-Claire, Rosemont and Notre-Dame-de-Grâce.

In the case of Mount Royal, it's the larvae that are causing the most trouble, said arborist Daniel Pilote.

Arborist Daniel Pilote says the larva feed on sap inside the ash trees. (Radio-Canada)

"It's crazy how such a small beast, that measures around three-fourths of an inch long, can kill a tree," he said.

The horses work alternately every hour and have a shelter on site where they can rest, eat and drink water.

When they aren't working hauling logs, the horses earn their keep giving sleigh rides at local sugar shacks on the weekend.

During the first half of the two-week pilot project, a total of 200 ash trees were carted away. The work has to be done by March 31 because of the beginning of the bird nesting period.