Wisconsin Blue Wing Olive Hatch (Baetis)

by Bob Mitchell
While most anglers in the early season are searching for the big Dark Hendrickson, around here the most predictable hatch in the spring is the Baetis or Blue Wing Olive. It seems to be true that the emergence of the larger (size 12) Hendrickson dun will draw lots of trout to the surface, particularly large ones. However, the little Baetis seems to be the bread and butter of the trout’s feed bag.
The only real problem with this mayfly is that you don’t always get what you expect. You might have great fishing to duns for three days and then they just don’t appear on the fourth day. Or maybe the pattern that worked so well on Tuesday and Wednesday won’t work at all on Thursday. In order to fish the Baetis successfully, i.e. be prepared for any contingency, you need to carry half a dozen patterns and be prepared to change strategies in order to cover all the bases.
First, you need to carry a nymph. Baetis nymphs are rather slim, so carry a pheasant tail or a sparsely dubbed hare’s ear. Baetis is classified by taxonomists (biologists who don’t have enough to do) as a small minnow mayfly, meaning that it’s a damn good swimmer. If you use a weighted fly, you might want to jig the fly slightly to produce some movement. If you use an unweighted fly, put a split shot on the leader and fish the fly just off the bottom.
Second, carry an emerger. To mimic an actively swimming Baetis, fish our Blue Dun Emerger downstream and across. Remember, Baetis are good swimmers. To mimic a Baetis that’s struck in the film, fish a floating nymph or Tracy’s CDC Baetis. They get stuck there because they’re so small they have a hard time breaking through the surface tension. It’s one of the reasons they seem to emerge from riffles – the surface tension there is already broken.
Third, carry a couple of different dun patterns. Why, you ask. The answer is that every pattern produces a different profile or behavioral characteristic. Some days they’ll prefer one profile to another. Other times it will seem as through each fish will want a different pattern. If you tie your own keep your patterns slim to better mimic the naturals. A quill or biot body will accomplish this but if you prefer dubbing, a good color can be obtained by mixing brown, grey and olive in equal amounts. If you purchase your flies the Comparadun or Sparkledun are beautiful frauds.
Fourth, carry two spinner patterns, one wet and one dry. While some species of Baetis lay their eggs on the surface, some crawl or swim to the bottom to lay theirs. The spinner fall usually occurs in the evening or late afternoon, but can also occur in the morning. Most of us have had the experience of being in the stream after the hatch has shut down while the fish continued to rise. We couldn’t see anything so we assumed the fish were eating midges. They were probably eating spinners, which is why you didn’t catch anything. If you carry a few you’ll be catching fish when no one else is. That’ll make you feel like an expert.
Hexigenia is a big mayfly, with the duns measuring approximately 30 millimeters. This is one of those hatches that causes fish to strap on the feed bag. Please note that I said “fish” and not just trout, because lots of other fish will eat these insects if they’ve got the chance. When walleye anglers start complaining about the walleyes being off the feed you can pretty much be assured that it’s because the fish have switched over to these large and succulent insects. Which of course gives walleye anglers fits because they can’t break out of the leech-on-the-bottom mentality. In fact, walleyes will even feed on these insects on the surface like bass or trout!
Generally speaking this hatch progresses from the west to the east and from the south to the north. It usually starts showing up around Park Rapids about the 10th of June, starts around Grand Rapids a few days later and Ely a week or so later. It’s usually reliable on the North Shore by the 4th of July. Old Timers swear that you can count on it on the Brule or the White by June 15th but it doesn’t seem to really rock n roll until a week or so later. The Clam has a fishable emergence about the same time.
In most areas the emergence lasts two or three weeks, but I’ve found Hex on the Kinni as late as August 8th. The Kinni used to have a massive Hex hatch but for some reason the numbers have dwindled. The last time I saw a fishable hatch on the Power Line Pool was in the mid 80’s. Today your best bets for fishing this emergence will be on wilder rivers or lakes farther from home. Naturally we carry Hex patterns, some of which are unique to our shop, but if all you do is carry a # 8 White Wulff you’ll be in business. Fish it with some action as the Hex makes quite a commotion on the surface when emerging.

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