The Name Game

I had a few responses trickle in via e-mail (troutfodder[at]gmail.com) in response to this photo from a few weeks back:

Ameletus dun shortly after emerging, with nymphal exuvia to the lower left

Most people thought a Parachute Adams would be a good choice to imitate the newly emerged dun. While that fly would certainly be a good match for the slate gray dun, this is a good example of where moving beyond the simple formula of matching color and size has its advantages. Knowing that this hatch is the mayfly genus Ameletus provides the fly angler with an additional piece of information crucial to making the right fly selection.

Rather than emerging mid-stream like many other mayflies, Ameletus emerges by crawling out on stream side rocks - making the dun stage of the hatch unavailable to feeding trout. Dry flies and emergers are not the way to go during an Ameletus hatch.

Ameletus Dun waiting for wings to dry before it flies to stream side vegetation - along with
two nymphs making their way out of the water to emerge

Ameletus nymphs fall into the mayfly swimmer category - they have three tails with interlocking hairs that allow them to swim rather quickly in short bursts. Nymphs of this genus tend to occupy slower moving water, and for that reason many authors discount them as an important food source. But even though they have a propensity for slow water, they still can be found in good numbers in faster freestone streams - they just tend to occupy the margins where the current is slackened. During emergence migrations, as the nymphs dart around, some get themselves into trouble by getting caught in the faster current. A dark brown nymph in size 12 or 14 is just the ticket to imitate these nymphs.

Ameletus nymph crawling onto a stream side rock to emerge
(note the dark wingpads that are characteristic of a mature nymph)

Ameletus have two emergence periods on most waters in Alberta - one early in the spring, and one late in the fall. This puts them on the menu when little else is available. In fact, the only hatch that typically overshadows an Ameletus hatch on the waters I fish is a Baetis hatch. If Ameletus are hatching, and there are no Baetis to be seen, an Ameletus nymph is what I reach for first.

If you look at the nymph in the above picture and compare it to a Pheasant Tail nymph, it is almost a perfect match. Drifting a Pheasant Tail (size 12 in the spring, and size 14 in the fall) will usually connect you with a few fish on those cool slow days. And aggressive line mending makes the fly move in short spurts characteristic of Ameletus attempting to swim to safety.

So, why bother learning the names of the bugs that hatch on your local waters? Quite simply, knowing what genus or species you are dealing with open the door to a wealth of information that greatly narrows down fly selection and tactics. It's all part of the formula of matching the hatch.