Black fly season typically starts in the middle of May and runs through late June or early July. They're often gone by mid-July but a cold, rainy start to summer (like 2017) can extend the season into August. Swarms often appear around creeks, rivers and streams.

What makes black flies go away?

Here are some tips for repelling pesky black flies:

Wear long sleeves and pants when outdoors. Wear light-colored clothing (flies are attracted to dark colors) Wear a hat with attached netting to prevent flies from swarming your face. Try natural repellants, like vanilla extract, lavender, and pine branch extract.

How long does it take for black flies to die?

However, they can obtain oxygen from both water and air, allowing them to survive in case water levels drop. Adults emerge in a bubble of air, formed inside the cocoon just before moulting, which they ride to the surface. The life cycle of a black fly can be completed in 3–4 weeks.