Bronte Creek Green Drake Mayfly Study

The Green Drake mayfly, Ephemera guttulata, an environmentally sensitive insect that is characteristic of unspoiled trout streams in Southern Ontario, has in the last ten years nearly disappeared from some waters where it used to be abundant, most notably the Credit River, raising concerns about the quality of those streams.  See for example an article in the Toronto Star entitled, “Is mayfly’s demise a clue for the wise.”

The extent of the decline of Green Drake, and its causes are being investigated by Henry Frania, an Entomology Research Associate at the Royal Ontario Museum.  Results of the study are being posted on the website of the Izaac Walton Fly Fishing Club as they become available. The presence of  Green Drakes on some sections of Bronte Creek, first noted by Brian Greck and Al Seabrook, shows that at least portions of this creek are still in sufficiently good condition to support these mayflies, but difficulty in finding the nymphs indicates that the population is in decline.  John Gordon, a student in the Postgraduate Environmental Studies Program at Sheridan College, is assessing the status of this mayfly on Bronte Creek.

For more details about the disappearance of the Green Drake mayfly, read Henry Frania's Green Drake Study prepared for the Izaak Walton Flyfishing Club.