Tiny Blue-Winged Olives

This genus is not well-known to fly fishers yet because most of its species were, until very recently, classified as either Centroptilum or Cloeon.

These mayflies may be abundant enough to cause fishable hatches in spite of their tiny size.

It's difficult to discern from previous angling literature exactly which statements now apply to Procloeon, because its species come from other little-known genera and the accounts for them conflict. They were mentioned in combination with other genera, adding to the confusion. So the information below is highly tentative and, where accounts seem to conflict, both have been given.

This species produces very strong hatches on fertile Western spring creeks. They are extremely small mayflies but may be extremely numerous.