Cluster Flies

I live in LaPeche, Qc. My south facing outside wall is covered with Cluster flies and they are starting to come in through the basement windows. How do I get rid of them? They are all over the walls and I can’t reach those high on the walls. Is there a kind of insecticide powder I can put along the bottom of the walls and balcony?

Click here for a Government of Canada pub on their control. Any flies that gain entry can be knocked down with an aerosol spray and vacuumed up.