Found this on Flyfisherman.com - Visit their site for a larger chart to print.

One of our visitors (happens to be be a Credit River angler) commented some excellent advice regarding fly hatches. With his permission, here is his information:
In answer to your questions. hatches are dependent on their immediate communities. Therfore, a hatch in one river can vary signfigantly from another which may be very close in [...]

Visit Credit River Anglers Association for the hatch chart.
The fish in this river are some of the best fighting and most beautiful stream trout to be found in Southern Ontario. There is no and has not been any stocking of browns and rainbows for decades, so the fish are “wild” in the [...]