Angling Entomology: Five Hatches for the Driftless
Updated: Oct 2, 2021
The Driftless is not a very hatch driven fishery and it seems to be increasingly less hatch driven (for more, read Aquatic Insect Declines?). I catch most of my trout on dry flies but it is not the "match the hatch" fishery that many rivers are. There are some really good hatches and times that they are keyed in on particular "bugs" and even stages of bugs. However, much of the time, the hatches are not dense and fish are not that picky. But often they are looking up - or at least they are willing to look up - if you can gain their attention. Without question, I catch most of my trout on dry flies - a CDC and Elk and some form of terrestrial are responsible for the bulk of these fishes. In my experience, the Driftless is an attractor fishery much of the time.
Previous angling entomology posts said to learn a half dozen or so of your best hatches - these are my five choices for the Driftless. Click the linked "bugs" to take you to that section.
For each hatch, I give a bit of background on the different stages (to review that, read the previous Angling Entomology post on life cycles. I try to provide a bit of my experience fishing these hatches - but it tends to be more than a bit dry fly-centric. Lastly, I give links to videos for some effective fly patterns beginning at their larval stages and ending at egg laying, spent, and/or spinner patterns. Compared to my typical posts, this one got a little long - I suppose I could have broken each hatch into its own page - but I wanted to keep them together in one place. It should serve as a good reference in the future.
Grannom Caddis (Brachycentrus spp.)
This is the hatch I most look forward to each year. This is the one hatch I can say I have not missed in the past dozen or more years. It is the hatch that I have not failed to have a 50+ fish day - all on dry flies - at least once each season for the past decade or so. I put it first because for me, it is the best hatch of the season.
Like most hatches, it is a hit or miss affair. I expect to see Grannoms in mid-April and the hatch might last for a week or two under the right conditions. This is a mid-day hatch - I normally start seeing them maybe around 11 AM but more typically after noon and they'll hatch in good numbers for about two hours. By mid-afternoon - say 3 PM - the hatch tends to wind down. The species we see on Driftless streams is Brachycentrus americanus, the American Grannom. The famed "Mother's Day" caddis of the Western United States is a close relative (B. occidentalis). There are probably a ton of ways to fish this hatch but I would never know - I put on a caddis dry, cast it out, and give it a little movement. Sixty percent of the time, it works every time!
Brachycentrus appalachia cased larva Source: Wikipedia; photo by Bob Henricks
As larvae, Brachyentrus are tube case makers that make their cases from organic material. Pick up a rock in a Driftless spring creek riffle and you are likely to see a whole bunch of these - particularly in April before they hatch. Their cases are sometimes called, "chimney cases" as they are rectancular with a slight taper. They are collectors and scrappers meaning that they are filter feeders, eating small particulate organic matter but they also scrape algae from rocks as a food source. In his wonderful book, Caddisflies, Gary LaFontaine writes that they are grazers by day and collectors (filter feeders) at night. He also reports that as larvae, they will repel by a silk line to move downstream and find a new suitable spot. LaFontaine and others write about fishing a cased caddis larva imitation and using a white marker to color your tippet to imitate their silk repelling line. I can't say I have ever tried it but maybe this upcoming spring.
Image of a Brachycentrus pupa - recovered from a case. Image by Drew Bennett in Matthew Green's article in Fly Fisherman Magazine on the Brachycentrus hatch. Read the article for a much more complete treatment of this hatch.
They begin to pupate in their case and then they complete their emergence in the surface film and often dead drift for some length before transitioning into adults. They emerge during the warmest part of the day - I typically encounter the best hatches on sunny days. Despite this, the mid-April water is not that warm so it is a bit of a struggle to hatch to their adult stage. I honestly do not fish this stage often but it is a very important one. There are a number of effective pupa patterns and I think my favorite dry fly, Hans Weilenmann's CDC and Elk, is fairly effective as a late stage pupa pattern with the wispy CDC fibers representing legs and the pupal shuck. Most of the time, I am fishing Grannoms, it is the "just turned into an adult" stage before they lift from the water to go to streamside vegetation, rocks, and woody debris to mate.
Grannom caddis return to the stream to lay their eggs underwater but being quite active above the surface, trout will often rise to eat them in a more active manner. At this stage, they are active fliers and your classic dead drifted dry fly is much less effective than a moving fly. It is also a whole lot of fun to catch fish that are actively chasing your dry fly. Once again, I am typically fishing a CDC and Elk as my dry fly. It is "skitterable" and even drifting, it looks like it is moving with those CDC fibers moving in the lightest of breezes or currents. Because I am typically imitating the female that is carrying a bright green egg sack at the end of its abdomen, I have added a little "Glo Brite" floss or something similar as a tag to represent this egg mass. I do not get overly concerned with color and usually just use natural CDC but you can use darker natural feathers or dyed black if you think color is important. A fly that you can get to go under the surface a bit is very effective. If you are into wet flies, this is a great opportunity to fish those to active fish.
For a very good article on this hatch, read Matthew Green's article, "Brachycentrus Hatch on The Country Mile" on the Fly Fisherman website.
Some flies to imitate the Brachycentrus hatches - with links to videos:
For an excellent presentation on the Grannoms in Wisconsin, watch Tom Lager's presentation to Fox Valley TU.
Blue-Winged Olives (Baetis spp. and a number of other genera)
These are a probably the most consistent hatch throughout the season. As their name suggests, they are olive mayflies with bluish wings - really more gray than blue. These little mayflies - they run from a #14 on the big end to a #26 or smaller on the small side if you include the species referred to as "tiny blue-winged olives" such as the genera Pseudocoleon and Acentrella - hatch from about March through the end of the season in mid-October. In part this is because blue-winged olives include at least three different genera (and almost certainly more) so it is not a single hatch but a number of hatches throughout the year. Baetidae, the family that contains these species, is Exhibit 1 in why it is not really worth learning too much taxonomy. Their taxonomy is in a state of continual reorganization and when I am going fishing and come across a #18 BWO hatch, I do not really care exactly what species I am fishing. Additionally, some of the species have multiple generations within a year. The Baetis that hatch in the spring will produce offspring that hatch in the fall.
When I think of a BWO day, it is an overcast, drizzling, or light rain day - though this is a bit less the case in the fall, it seems. BWOs rarely hatch on sunny days; the exception being that you will see them hatch on sunny fall days on occasion. Their nymphs are swimmers and are often associated with instream vegetation but you will also find them on and between rocks in riffles. The are matched very effectively with Sawyer's pheasant tail nymph and I am sure many of the Perdigons and other slim "new age" nymphs are effective imitations as well. BWOs are very common in Driftless streams and I am sure that a great number of times that your nymph is eaten - particularly on overcast days - are when BWO nymphs are active. Tie some of your pheasant tail nymphs without beads or weight to allow them to rise thought the water better. Another effective way to fish the nymphs is with a soft hackle that you can allow to be pushed to the surface by the current in a down and across presentation. Additionally, that same soft hackle can be swam by using short (1 to 4 inch) twitches to move the fly like the naturals as they swim towards the surface to hatch.
Nymph fishing is great but I am a bit of a dry fly snob and BWOs provide some great dry fly fishing. Being swimmers, their nymphs may make it to the surface more quickly than other mayfly species however hatching often in cool weather, they often take some time to transition from naiad (nymph) to sub-imago (dun). This means that they are often quite susceptible to trout as their wings are drying. It also means that fly patterns that imitate this slow or stuck transition can be really effective. These patterns range from floating nymphs to a sparkle dun which imitates the dun with its nymphal shuck still attached. There are a huge number of "emerger" patterns that imitate the transition between nymph and the winged dun. For the duns or spinners, I find parachute flies to be effective and visible. For picky trout, my favorite dry is the thorax dun.
Some flies - with links to videos for tying these patterns.
RS2 (particularly for smaller BWOs)
Crane flies (Antocha spp.)
Crane flies are not a hatch that draws much interest in most places but in the Driftless, they are one of the better and longer-lived hatches in the region's streams. First, a bit of taxonomy. Craneflies are in the order Diptera, the true flies which also includes house flies, midges, mosquitos, and a host of other flies that have "lost" their hind wings. I am going to make this entry shorter than the rest as I covered much of the same information in the post, In Praise of Crane Flies.
Crane flies tend to be a mid-May through June hatch - though this year they came a little earlier and in less numbers that usual. They are of some importance as larva though many of the fly pattern you will see are meant to imitate the larger Tipula spp. crane flies - the mosquitos on steroids. Most craneflies like damp environments but not all of them live in streams. Instead, many crane fly larva live in forest leaf litter and along the margins of streams. The Antocha species we have in streams are riffle-dwellers, holding on to rocks and feeding on algae and detritus. The biggest thing to know here is that they are smaller than most crane fly larva patterns you see. My favorite larval fly pattern in the Brush Hog, a simple fly pattern. They tend to pupate near shore and are unimportant in that stage. However the adults are really important and tend to be quite active as they return to lay eggs so a pattern like the Coulee Crane Fly which can be skittered is an effective imitation.
There are other genera of crane flies - most notably the "mosquito on steroids" in the family Tipulidae - but in the Driftless, most of our fishable crane fly hatches are in the family Limoniidae. But there is no reason you should care much about that. What you probably care about is that they tend to orange or yellow and can be imitated with a #14 through #18 fly pattern. All that said, a Killer Bug or Utah Killer Bug are simple and effective large crane fly imitations - and they probably are mistaken for a scud as well.
For more about craneflies in Wisconsin, read the post, In Praise of Crane Flies.
Some flies for imitating crane flies.
Coulee Killer (no video - but a good blog post)
Adult Crane Fly (Coulee Crane fly - no video)
Tan Caddis / Spotted Sedges (family Hydropsychidae)
There are a number of Hydropysche caddis species and for our purposes, we really do not care much about their taxonomy. Hydropsyche are our late-spring and early-summer caddisflies. I am fishing these mostly from May and June and mostly in the morning and late in the evening.
Hydropsyche caddis are referred to as net-spinning caddis because as larva they make a small net of silk. They also produce a small retreat attached to a rock within a riffle and occasional venture out of this retreat to clean the food that their net captures. They are one of the most abundant and important collectors (for more, read the post on the River Continuum Concept) in streams. Their color varies by species - there are about 70 species in the genus Hydropsyche - but most larva are tan or an olive green. Like all aquatic insects, on occasion they get caught in the current and are swept downstream. There are a number of effective larval patterns like Czech-style nymphs that have a distinct thorax section like the naturals.
They pupate in the riffles and runs in which their net-spinning larva live. Pupa then move to the surface of the water where they hatch into adults. Depending upon the conditions, it make take some time for their adult wings to dry and for them to be able to fly away. This, of course, makes rather vulnerable to predation by trout. This is typically the stage that I am imitating with my dry fly. After moving off the stream, they mate and the females return to the stream to dive underwater and attach their egg mass to rocks. After laying eggs, the exhausted females drift to the surface where they recover and eventually fly off. As you can see, there are several stage where they are quite vulnerable to trout - thus their importance as a hatch in much of North America. A classic wet fly or soft hackle can very effectively imitate the driving female and any number of dry flies work well for both the emerging adult and the recovering female. And you should probably have at least a couple of spent wing caddis imitations for the recovering females. If you are sensing a trend here, I usually am using a CDC and Elk, often skittering it, and at times allowing it to be drug underwater to imitate adult Hydropsyche caddis.
Some fly patterns with links to videos:
Winter Hatches - Stoneflies and Midges
There are probably not our best hatches but in January and February, it is fun to catch a few trout on dry flies. Neither of these hatches tend to produce "hot and heavy" dry fishing like the Grannoms. Instead you should expect a short burst of activity, often not much more than a few minutes. And over the course of a few hours, it can add up to some pretty good fishing but you are relatively unlikely to catch fish cast after cast. Part of what puts these two hatches on this list is their novelty, the fact that you can catch fish on a dry fly on a nice January or February day.
Stoneflies are generally pretty simple to understand. They spend a year as a nymph and then generally crawl to shore, instream rocks and debris, or overhanging vegetation to transition from nymphs to adults. There is no pupal stage as there is in some other aquatic insect hatches. Fish the nymph patterns near the bottom, often in rather heavy water. In the winter, this is not a place where trout are always hanging out but I have had good luck on stonefly nymphs where riffles dump into pools. As dry flies, you are usually imitating egg laying adults as their emergence to adulthood generally occurs above the water surface. Normally I fish them dead drift this time of year but don't be afraid to move your fly if they are not hitting your dead drifted dry fly.
Unlike stoneflies, midges have a complete metamorphosis meaning that they transition from larva to pupa, to an adult. There larva are simple and I often fish them effectively in really slow pools. While midges will occur in pools, they often live on vegetation and in soft sediments of pools. They transition to pupa and then adults relatively quickly but because of the cold water temperatures in the winter, this occurs more slowly. There are any number of effective pupa patterns, many of which do not look much different from a larval pattern except that their thoraxes are bulkier. As adults, they tend to be pretty small as well - #18's are a "large" midge on Driftless streams. As such, many anglers opt for a cluster pattern as dry fly imitations; the most famous of which is the Griffith's Gnat.
Winter Stonefly imitations
Zebra Midge (there are a gazzillion versions)
Depending upon where you fish, you might run into a larger diversity of hatches than I tend to. There are still some other mayfly hatches - the sulfurs (Ephemerella spp.), Hendricksons (E. subvaria), March Browns (Maccaffertium vicarium), and others but they are more miss than hit in the last decade or two for me. Hopefully you have had better experiences with these hatches in recent years. If I were to add a sixth hatch, it would probably be the late summer Trico mayfly hatch - or more accurately its spinner fall. You will certainly come across other caddis hatches - in particular, the Chimarra (little black caddis or sedges) can be very good as are some of the fall caddis hatches. We do not have much for stonefly hatches but the Yellow Sallies can be a fishable hatch. And there are seemingly always midges hatching; they are not just a winter hatch, they just seem to draw more attention then.
Trout in the Driftless are often "looking up" even if there is not a concentrated hatch that trout are focusing on. Between these common insects and all the terrestrials, the Driftless is a great dry fly fishery.
This was an information-dense post, to be sure. Hopefully it serves as a good reference as you encounter these hatches or to be used in anticipation of hitting one of these hatches and thinking about tying flies this winter. I tried to give you enough to work from but not so much that the information was too overwhelming. With the fly patterns, I tried to give about a dozen different patterns, not that you should expect to carry all of them but as a way show the diversity of ideas out there to imitate these insects. There is a lot to know and learn here and you will not be able to do it all at once. Come back to this page after encountering one of these hatches and leave your experiences, favorite fly patterns, and such in the comments.
For the next angling entomology post is six hatches to know for Wisconsin streams. For now, some sources to better know and understand Wisconsin hatches.
Wisconsin Hatch Charts
Central Wisconsin Hatch Chart (Fox Valley TU)
Northern Wisconsin Hatch Chart (WiFlyFisher.com)
Driftless Wisconsin Hatch Chart (one I did many years ago; Silver Doctor Fly Fishing)
Important Insects for the Midwestern Fly Fisherman (FlyFishingWisconsin.com)
Wisconsin Emergence Calendar and Emergence Database (Patrick Hager, Wisconsin Fly Fishing)
Midwest Hatches (Global FlyFisher)
Websites for Angling Entomology
Fly Fishing Entomology Basics (The Fly Fishing Basics)
The Orvis Guide to Fly Fishing Entomology
PLaylist for Simple Entomology - Rog and Jane Klettke
Hatches - Understanding Caddis, Mayfly, Midge, and Stonefly Hatches - The New Fly Fisher
Talking Trout - Aquatic Insects with MIke Miller, Wisconsin DNR - Wisconsin Trout Unlimited
Tim Cammisa - Stream Sample with Entomologist Matt Green - Part One and Part Two