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Are mayflies in trouble? with Robert OHarrow

Description: This week my guest is award-winning investigative journalist Robert O'Harrow, who has been with the Washington Post for over 30 years. Last fall he wrote an extensive article on the threats to mayfly populations worldwide and is continuing to research this issue, so I thought it would be interesting to share his findings. Bob is also a lifelong fly fisher who admits he didn't know a lot about the plight of mayflies in the past, so he gives us a great perspective.
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Podcast Transcript:

Tom: Hi and welcome to "The Orvis Fly Fishing Podcast." This is your host, Tom Rosenbauer, and my guest this week is Robert O'Harrow. Robert is an award-winning journalist from "The Washington Post." He's been with "The Washington Post" for over 30 years. And last fall, he wrote an article, a thoroughly researched article about mayflies and the threats to mayfly populations worldwide. So, on the podcast today, we're going to discuss mayflies, why they're so important, the threats to their abundance, and also what individuals can do to help combat these threats to these amazing insects that we all know and love. So, hope you enjoy the guest today. But first, we're going to do the Fly Box and the Fly Box is where you ask questions and I try to answer them. You can send me a question by sending an email to You can either just type your question in your email or you can attach a voice file. And please try to keep your voice memos to less than two and a half minutes, preferably two minutes. If they're longer than that, I probably won't read them.
Well, let's start with an email. The first one is from Daniel. "Hey, Tom, I loved the podcasts. I really enjoy the mix of readers' questions in the Fly Box followed by guest. I feel like I'm always learning a ton with that format. Just so much great information in each episode. I was listening to a recent podcast, "Tips on landing and netting fish," with Jesse Haller. And one of the Fly Box questions was about bass tournament anglers using permanent marker on their line. As an avid bass angler and former tournament angler, I thought I should share some insights as to what we're doing. It's not done to the fluorocarbon line, at least not by anyone who actually understands why we are marking the line. We mark up braided line when using high visibility lines or when the line starts to fade and brighten up from use.
The smarter anglers will not create a solid mark, either dashes or just inconsistent marks up the line will break up the straight solid line the fish would otherwise see. This really comes into play fishing around or in weeds. It's like camouflage clothing, it breaks up something that would otherwise stick out like a sore thumb. My question is about nets. I do a lot of multi-species fishing on the fly rod and lately, a lot of fly fishing for bass in the Great Lakes watershed. We get a lot of fish in the three-pound-plus range and four and five-pound fish are not rare.
When I'm in a boat, it's not an issue, I just use the bassinet, but that is far too cumbersome to use when I'm wading. My trout net is all too small and I fear too delicate for some of the larger smallmouth bass and the spike dorsal fins that come along with them. What would you suggest as a good net for bass while wading? I'm thinking I would like to use it for steelhead and when I am targeting bigger trout on streamer flies, but that's not really a deal breaker. A side note, I just purchased the Orvis guide sling pack, so I have a net carrying options and I can't wait to get on the water with it. Thanks for being a great resource to the fly-fishing community and for always being so informative and entertaining."
Well, I don't know how entertaining I am, Daniel, but I want to thank you for clearing up that issue of people marking their lines, bass anglers marking their lines with a marker. That absolutely makes more sense what you just told me. So, appreciate you clarifying that. Regarding the net, I think the best net for you in that instance is a long-handled wide-mouth net and the new Orvis wide-mouth guide net is a terrific net for what you're going to do for bass and larger trout. I use it myself when wading and like you, I'm tired to try to reach out with a short-handled net when I'm netting fish and if you got a fishing buddy, it's even better using those long-handled nets. So, it's just a great net and yeah, it's a little longer and you have to stick it in the back of your waders or figure out a way to carry it.
But it's not that obtrusive and I find it to be handy and I'm carrying it more and more just on my regular trout fishing trips unless it's in a really small stream. However, it'll work fine for bass, it'll work fine for bass and large trout and even carp, we've used for carp quite a bit and they're fairly large. But I don't think it's going to work for steelhead, it's just not big enough for steelhead. For steelhead, you're going to have to get something that's got a bigger, deeper net and there's nothing that Orvis sells that's really appropriate for steelheading. Some of the Orvis stores will carry nets...some of the Orvis retail stores will carry nets appropriate to steelhead fishing, which have a much bigger bag and wider net opening button and nothing you can find in the Orvis website is going to be appropriate for steelhead.
Don: Hey, Tom, this is Callahan from Colorado. So, my question is about etiquette in educating other anglers about...educate on the river. Now, in Colorado, there's a lot of new anglers, especially after COVID. And I've noticed, over time I've been getting front hold, there's no better way to say it, by people that probably don't understand the etiquette behind fly fishing. So, my question for you is, is it polite to educate maybe somebody that is not aware of the etiquette of them, of giving others space on the river? Or will you just kind of come off sounding like a rude person? So, that's my question. I've just noticed, kind of gone by the wayside on Colorado rivers these days. So, that's my question for you. Thanks very much.
Tom: So, Callahan, I understand your frustration but it's not your problem. I don't think you want to try to educate anyone on the river as to what crowding is and isn't. You know, it's going to ruin your day, it's not going to be pleasant, and it's gonna ruin their day. Even if you try to be polite and try to educate them, a lot of people are going to take it the wrong way. So, you know what? It's not your problem. If I were you, I would just move and go somewhere else. You know, Colorado is crowded, the trout streams are crowded, but there are lots of places in Colorado where you can get away from the crowds and I'm afraid you're just gonna have to move around and explore some new water to find those less popular places.
You know, it's really...educating newcomers to proper etiquette on the river is really responsibility of people like me or people in the fly shops that sell someone their first outfit. You know, everyone that's sold a fly rod outfit should be given just a little talk on crowding on rivers and how to avoid it and what's cool and what's not cool. I've actually done a video that's on the Orvis Learning Center and YouTube's called, "How to behave on a trout stream," which addresses this issue. So, yeah, it's not your problem. If I were you, I wouldn't. You know, it's like if you saw someone using poor etiquette in a restaurant, would you walk over and make a suggestion to him? And it's kind of a similar thing. Yeah, it's not your problem, it's mine, and I'll do the best I can.
Here's an email from Kevin from Bozeman, Montana. "My son and I were fishing a small tailwater in Montana last week, and we did very well, landing 8 to 10 fish each. They're mostly browns and a couple of whities and a rainbow. The thing we found odd is that they were all in the 16 to 20-inch range, which was awesome, but we were wondering where all the smaller fish were. We had different flies ranging from size 10 down to size 20, and it didn't make a difference. Any idea why this might be? Do the big fish out-compete the small for the fly? Maybe the larger fish push the smaller ones into less desirable water. No complaints at all in the fishing, but we were just curious what might be going on?"
Well, Kevin, that's a great question. And, you know, I've asked myself that too and I realized over the years that no, the big fish are not beating the small fish to the fly. In fact, it's usually the opposite. It's usually the smaller fish beating the larger fish to the fly if they're inhabiting the same water. But what you find in rivers is that the big fish are going to take the best feeding positions and they're going to push the smaller fish out and, you know, the brown trout are going to go to eat some of the smaller fish. So, the smaller fish are going to tend to be in different kinds of water. Smaller fish that I've observed over the years, smaller fish tend to be in shallow areas with lots of brush.
So, imagine a riffle with a tree overhanging it or branches hanging in the water, or a dead tree in the water in a shallow riffle. Those are the places the small fish are going to be. They're in there because they know the big fish aren't going to be able to get them there and, you know, they're going to be near some protection. But they're going to be in different areas of the stream and usually, areas that we don't fish. The other scenario that can happen is that most of the smaller fish will be in the tributaries and they're really small tributaries. And as they get bigger, they'll drop down into the bigger river. But, you know, you were just fishing in an area where it was prime water and the bigger fish were inhabiting that water and there's probably...if they're wild fish, there's small fish around somewhere but they're just not in that particular area of the river.
Here's an email from Nick from Richmond, Virginia. "As always, thanks for everything you do for this sport. Two quick questions for you. Well, I guess they're for Jesse Haller and Tim Flagler, so thanks in advance for playing the middleman and a request. On last week's podcast with Jesse Haller, He mentioned having a working box on the water. I assume this is a strategy that competitive anglers use to maximize their efficiency. I often carry more boxes than I need on the water and I'm curious about this strategy, and whether or not it has an application for non-competitive anglers. Question two. In Tim Flagger's fly-tying videos, he usually cuts his tying thread with a sharp edge, not scissors, which I've gathered as the sharpened end of his whip finisher. Is this something you do as well? If so, what's the best way to sharpen a whip finisher?"
So, in your first question, Nick, yeah, that's definitely something that is not restricted to competitive anglers having a working box. And, you know, you have to know a river, first of all. You know, it has to be a river that you fish regularly because if you're on a new river, you never know what hatches you're going to see or what flies the fish are going to respond to. It could be a nymph, a dry, a wetter, a streamer. And so, you're probably going to want to carry all those boxes on a new river. But if you're on, you know, your familiar river that you fish all the time, you know what flies you're probably going to need in a day. And you can just pull an assortment of those flies from all your other boxes, put them in one box, and then, you know, you're going to be lighter on the river, you're going to have less weight to carry.
And, you know, what I often do is I'll leave my other fly boxes in the car. And, you know, if suddenly there's a hatch that occurs that I haven't seen before and I don't have something to imitate it, then I can always run back to the car if I want to and get that fly. Quite honestly, often I'll try to make something work out of my working box. But anyway, that's all there is to it. It's just you have to really know a river or have some intelligence and then just pulling various flies of various types from your bigger boxes into a working box. Regarding the cutter that Tim Flagler uses, yeah, it's just he sharpens the end of his whip finisher and, you know, you can do this with lots of different things.
You could do it with a file and then you probably want to do it with a fine sharpening stone so you don't have rough burrs on it and you don't have such a rough edge. Or you can do it with a Dremel tool or anything you used to sharpen a knife or an axe or something. So, it's quite simple, you know, just file that end down to a point and then buff it with, you know, a fine stone or emery cloth or something to remove the burrs. And no, I don't do that. I should do that and you've given me a reason to go down into my basement workshop and file some whip finishers down. I've watched him do that for years and I've never been smart enough to do it myself, but you guys all know that Flagler is a lot smarter and more clever than I am.
Ian: Hi, Tom, this is Ian up in Vancouver BC, I was hoping that you could just maybe settle a debate between me and my buddy. We were up in the Canadian Rockies during the summer and we were fishing for cutthroat and we were having a great day, we were catching fish somewhere in the 16 to 20-inch range. And just towards dusk, I hooked a big fish on the dry fly, bigger than what we had previously been catching. So, this one was sizable. And I immediately felt like it was testing my line, it was trying to head towards some heavy current downstream. And as I was fighting the fish, I started going downstream with the fish trying to stay downstream of it and trying to pull it to the side. And ultimately, I failed despite my best efforts, the thing got into that heavy current and then broke me off.
So, my buddy who was watching the whole thing, you know, said, "Well, why did you start moving downstream with it? You should have just stayed put and fought it from where you were." We've asked various experts and got different answers, so hopefully, you're the tiebreaker. I was always taught that you try to stay downstream of the fish when you're fighting it but maybe I'm wrong. So, again, I don't know if the outcome would have been any different, but just hoping that you could give your opinion. Thanks for all that you do and taking the time to answer the question."
So, Ian, I'm with you, you know, if a fish runs downstream, if you stay upstream of that fish, you're going to be directly upstream of its mouth and there's a really good chance, number one, of the tippet breaking because the fish is going to have a lot of current to work with and a lot more pressure on your line and fly line in the water. The other thing is that the hook can pull out because you're pulling directly upstream on the fish. You know, my view and my opinion is you want to try to get at least even with the fish if not downstream of the fish, so that it has to fight against the current, not with the current. So, I think your buddy is absolutely wrong. It sounds like you might have hooked a bull trout too. You know, in a lot of those BC streams, you have bull trout, so it sounds like it might have hooked a bull trout. And you know what? You're gonna lose some fish, a tippet broke, probably nothing you could do about that. The fish might have gotten you around a logger or a rock and that's the way it goes. We don't land them all. If we did land them all, it wouldn't be that much of a challenge. But you are absolutely right.
An email from Steve from Idaho Falls. "Two or three months back, I decided to learn to fly fish. I have found both the podcast and your books incredibly helpful." Thank you, Steve. "My question relates to where a new fly fisherman should focus in an area like mine. The Snake River goes through my hometown and the famous South Fork of the Snake River and Henry's Fork are less than an hour away. So, I've been cutting my teeth somewhat unsuccessfully on these big rivers. Each have deep and fast water and what seemed to be really picky fish. As the cold weather is now made each inaccessible because of ice, I want to recalibrate my strategy for when the weather breaks. I know you recommend that someone new to fly fishing start with panfish in a pond. My problem is the nearest place with panfish is two or three hours away. That leaves the choices of small streams, reservoirs, or lakes, all primarily with trout. Out of those three types of waters, what would you recommend for a newcomer like me to learn on and why?"
That's an interesting question, Steve. First of all, I challenge you...that you don't have any panfish, I challenge you that you have to drive two to three hours for panfish. I am willing to bet that there...I know there's some good carp water near Idaho Falls and if there's carp there, there are probably some sunfish in there. Now, I wouldn't go chasing carp as a new fly angler because they're incredibly difficult and challenging. But if there are carp in the water, some of those reservoirs have got to have panfish. They might not be sunfish, they might be yellow perch know, I don't know what else but I'm sure that you can find some panfish close to Idaho Falls. And if any of you listeners know of some places near Idaho Falls with panfish, let me know. I don't know the area that well. I often fly into Idaho Falls but I'm generally going up toward the Yellowstone Henry's fork area. So, I don't know, but I guarantee you there's some panfish around somewhere.
But regarding those three types of streams or three types of waters, they all have their easy parts and their hard parts. First of all, small streams are going to have the easiest trout to catch. Particularly if know, the further you get from the road, the easier the fish are going to be to catch. So, if you've got a place where you can go up into the mountains a little bit to get away from people, they're going to be relatively easy to catch. Now, the casting is sometimes difficult because it's really tight casting but small stream fish are often quite easy. And if you can find that kind of, small streams that run like through meadows, some of the irrigation ditches and other small streams kind of down in the valley near Idaho Falls, those fish are going to be pretty tough because they're almost like spring creeks. But you want to get up into the hills, into the mountains where you've got some tumbling water and those fish should be relatively easy to catch.
Reservoirs and lakes with trout can be difficult, particularly if you don't have a boat. Pond fish can be really, really tough or they can be really easy. It all depends. If those reservoirs or lakes are stocked with trout and they're not wild and if they're freshly stocked, the fish are probably going to be relatively easy to catch. But if they're, you know, fish that have been in a lake for six months or a year or a couple of years, they're gonna be tough, they're gonna be really tough. The other thing you might consider is going further down on the Snake. You know, where the Snake River gets warmer, there are some smallmouth bass and smallmouth bass are particularly susceptible to the fly. They're not that spooky, they're really aggressive. So, if you do a little research and find out where there's some smallmouth bass in a river nearby, those may be another target. But I can understand, you know, going to someplace like the South Fork or the Henry's Fork, those are not easy rivers to fish, and probably it's best to practice somewhere else locally.
Here's an email from John. "Love the podcast and videos but I have to say, the one on when you use the reel seems a bit off to me. You're showing how you let the fish decide and proceed to lose a fish and say, "Well, it happens." But it seems to me in letting the slack line out, you probably gave him too much slack and that is why you lost the fish. Am I off base? What is the best way, especially if you have a lot of line off the reel, to let the fish take line without giving him too much slack and/or getting a good friction burn on your fingers?" Okay, John, well, I watched that video again and I definitely didn't give that fish in the video any slack. That fish took line and it took line and I use the drag on my reel. That's why it's important, if you're going to be in the big fish, to have a decent drag, a nice smooth drag on your reel to control the tension on your line.
You don't want to be trying know, if the fish is going to run, you don't want to use your fingers to slow down the fish, your fingers on the fly line because the line can get caught and you can't be that smooth by grabbing the line when a fish is running. You know, you just can't be as precise and smooth whereas the mechanical drag on a reel is going to put some tension on the fish, keep some tension on the fish, but it's going to be a lot smoother. So, if you have a lot of line off the reel and a fish takes off, the best thing to do is to try to feed that line through the guides.
Put your line hand and your rod as far apart as you can by sticking your arms out to the side, stick your rod arm out to one side and your line arm where you're holding the line on the other side, and just try to let that line feed through the guides and there, you are going to have to, you know, use your fingers to guide the line through the guides. But once that fish gets on the reel, then you want to use the mechanical drag on the reel. So, I hope that...and you shouldn't get a friction burn, you shouldn't be holding the line that tightly when you're feeding that slack through the guide, you should just be guiding it through there and letting the fish take it. So, I hope that explains things well. You know, you have to practice it. It's a difficult thing until you actually get out there and have this happen and learn what to do and what not to do when you have a big fish taking line.
Here's an email from Mitch. "This is Mitch from Central Washington, I have a question about UV resin over knot, specifically nail knots. I prefer nail knotting my leader directly to my fly line when putting on a new line, just as I did on my 408. I tried UV resin over the nail knot to both decrease the chance of snagging algae over my guides and to seal the end of my line to prevent water soaking into the core. So, my question is, does the UV resin lead to a greater probability of the line sinking? Adding to that, is fly line more likely to sink in slow-moving creeks versus faster currents? And do you think UV resin will make a difference in either water type? Of course, thank you for all you contribute to fly fishing, especially your efforts intentional or unintentional to keep elitism out of fly fishing."
So, Mitch, you had to be careful about using UV resin as something to smooth out your nail knot. Now, an ordinary nail knot, if you trim the ends carefully, it's gonna go through the guides pretty smoothly. And, you know, when I do it that way, I don't put anything over my knot, I feel know, without any little tag end sticking out, that knots gonna go through the guides pretty well and I don't worry about it. But if you want to put something on there, you have to be careful because UV resin, often a lot of them are fairly stiff and that's going to crack eventually, and it's not going to be flexible enough. You know? And you don't want to put a lot of it on there, you just want to put a really light thin coat of whatever over the nail knot. A couple of things that I might recommend you try instead of UV resin.
I know there's some UV resins that are supposedly flexible, but they're not as flexible as they should be for something like that. You know, there's a couple of things that you can try. One is to use a little Aqua Seal or just the stuff we use to patch our waders, just a really thin, thin coating of Aqua Seal over that nail knot. And the other thing you can try is shoe goop or Shoe Goo. But again, you may want to thin them down...I believe they thin down may have to check this, but I believe they thin down with alcohol. You don't want to put acetone on the end of your fly line because that's gonna hurt it but I think you can thin those down a little bit with alcohol. Somebody may want to correct me on that. But I wouldn't use UV resin, I think that it's going to be...not necessarily too heavy if you put a thin coat on, but it's going to be too stiff.
Here's an email from Anthony. "Thank you so much for all your time and effort in promoting fly fishing and so openly sharing your knowledge in the podcast. I just recently discovered the podcast and I love going back through the archives and listening to all your great advice. I just move close to some tailwater and know that nymphing is going to be my most productive approach in these waters. I've always heard of rigging up so the length from your indicator to your first fly is 1.5 times the target depth of the fish you're trying to reach. My question is how do you gauge depth in a river that can vary from eight-foot-deep holes to two-foot-deep ripples? Are you looking at the color of the water to determine depth? Visibility of rocks/bottom? Or just some good old trial and error by ticking bottom with some weight?"
Well, Anthony, it's really all of the above. And, you know, that 1.5 times the target depth is not an exact number, it's just a rough estimate of it. And sometimes you can go shorter than that, know, in really fast water, you may want to go longer. And in some situations where the fish are actively chasing nymphs up to the top, you can get away with your nymphs a lot shorter. So, you really going to have to experiment and, you know, you're right on with that good old trial and error. If you start ticking bottom every once in a while, every four or five casts, then you're probably in the right zone. If you're ticking bottom every cast almost right away, then you're too deep. And yeah, you can gauge the water depth by the color of the water.
It's going to be a darker...the deeper water is going to be a darker color. You know, if you can't see the bottom, you know it's going to be pretty darn deep. But, you know, you just have to guess, there's no absolute rule to that. And don't hold yourself to that 1.5 times, experiment with different lengths by moving your indicator up and down or if you're fishing dry dropper, you're going to have to tie and re-tie tippets. So, I advise you to start with an indicator because it's a lot easier to move it up and down. So, try everything, experiment, trial and error, and, you know, when your indicator is just occasionally ticking bottom and your indicator looks like it's dragging, it looks like it's moving a little bit slower than the surface currents, then you know you're in the right place.
Rick: Hi, this is Rick from Missouri. I'm trying out an idea, which is either clever or really dumb, and I would like your opinion on it. I have to trim my beard pretty short because I wear a CPAP mask at night. And when I use a beard trimmer, I noticed these little white hairs that come off look a bit like guard hairs from a hare's hair. So, I've been mixing my beard trimmings with pine squirrel and other non-spiky dubbings and it makes something that looks a little bit like hare's mask dubbing. So, I just would be interested in knowing whether you've tried this or have ever heard of it or maybe it's just a really terrible idea. Thanks a lot. Bye.
Tom: Rick, I think that's a great idea. I trim my beard fairly short and I'm going to try the same thing. But, you know, you can mix anything you want into dubbing, dryer lint, you know, stuff that comes out of your vacuum cleaner, it doesn't matter. You know, it's organic and natural those beard trimming. So, I think that's a cool idea. And, you know, especially if you have a salt and pepper beard, that's going to be a really good mixture to add to your pine squirrel. So, yeah, I think it's a great idea and try those flies out and see how well they work. All right, before we go talk to Robert about mayflies, I've tried to add some product tips into the podcast and I don't always remember, I apologize, But I did remember this week. And one of the new products that I am really happy with and excited about is the new PRO Waterproof Sling Bag. By the time you hear this podcast, it should be live on the Orvis website. And if it's not, it will be in another week or so.
This is a truly waterproof submersible sling bag. And I've been using one for about eight months now because sometimes I get to test the prototypes or the early samples. And I am someone who's not very tall, I'm vertically challenged, and with the standard sling bag, I'm know, it's behind me, usually when I'm wading, it's behind my back. So, I don't see what's going on. And I am invariably wading to a point where if I have to wade deep like cross a river, invariably getting water inside my sling bag because the existing ones aren't waterproof. And then my flies get wet and I have to dry them all out or else I have to worry about rusty hooks in the future and it's a royal pain. So, with this waterproof sling bag, truly waterproof, make sure you close the zippers, I've been able to keep all my flies dry.
I was in Chile this December, and we had a solid week of rain. And not only do we have a solid week of rain, but I was doing a lot of deep wading. In fact, one day, when crossing a very deep river, we only had about...we only had one place we could cross this river and it was pretty hairy. And I was with a big guide and the guide and I were locking arms and crossing the river and we saw fish rise and we stopped and cast to the fish about halfway across. And then the fish stopped rising and we decided to keep going across the river and I didn't wait for the guide. And I thought...I had a lot of confidence and I thought I could make it and I took one step and lost my footing and took a swim, started going downstream in this...well, not a super fast river but very very deep, where I couldn't touch the bottom.
And so, I took a swim. Luckily it wasn't too cold that day. And the guide jumped down and swam with me and together, we swam to shore and I was totally submerged, shall we say, except for my head. And when I got out of the river, I opened up the sling bag which had been floating along with me and my fly boxes were completely dry. So, there's nothing worse than falling into the river. I mean I don't mind falling into the river and getting wet, I know it's dangerous but, you know, usually, you can get to shore pretty quickly and, you know, you have your wader belt tightly cinched around you, so you trapped some air in your waders.
But getting my fly boxes wet is the worst because if you don't dry all those flies off, they're going to rust and they're going to be ruined. So, anyway, to make a short story long, I love this new waterproof sling. It's not inexpensive, it's $279, but waterproof zippers, good reliable waterproof zippers are very expensive. And so, watch your Orvis website for it. I highly recommend it, particularly if you're vertically challenged like me or if you fish a lot in rain or snow. You're gonna be thanking me for it. All right, that is the Fly Box for this week. Let's go talk to Robert O'Harrow about the amazing world of mayflies. So, my guest today is Robert O'Harrow. And Bob is an award-winning investigative journalist who has been with "The Washington Post" for how long? How long, Bob?
Robert: About 32 years.
Tom: Thirty-years years. And Bob is now editor-at-large?
Robert: I'm a contributing writer, which means that I've moved into kind of an emeritus stage at the Post.
Tom: And we first got acquainted...Bob did a credible article back in September called, "The World's Oldest Winged Insect is in Trouble, How Frightened Should We Be?" And it has to do with mayflies. And Bob, you're a lifelong fly fisher. And so, I thought it was just a terrific article and people should definitely look that up online. I think what did you say if you google "Washington Post mayflies," it'll come up?
Robert: Well, it's the only piece I think the Post is done on mayflies. But if you type in my last name, O'Harrow and mayflies, it comes right out.
Tom: Okay, great. So, anyway, great reading and some great photographs and it's an extensive piece, so it's definitely worth reading. So, we want to talk about mayflies today because they're so important to us as flyfishers. The whole tradition and literature and fly patterns and everything else has revolved around mayflies. Even though there are other very important aquatic insects, mayflies are kind of king in the world of fly fishing for trout. Why are they so important, Bob?
Robert: Well, I think the simple reason is that trout go crazy for mayflies. As anglers who've been lucky enough to experience a big hatch, they will just go out of their way to chomp on these wonderful insects. And we like to catch fish, naturally, and so that's one reason. Another reason and maybe a little bit deeper reason is that anglers can be an obsessive nerdy bunch, as we all know. And cracking the code of which mayflies or aquatic insects that the fish are eating when we happen to be there, that can be, you know, like four-dimensional chess and it's very engaging and it's really fun. And sometimes you think you're fishing, you know, above this hatch that's about to take off from the water, when in fact, you should be fishing about two inches down for, you know, a mayfly that hasn't quite emerged yet. It's kind of drives me crazy at times and that's what's so much fun about it.
Tom: It drives us all crazy. It drives us all crazy. And ecologically, you know, mayflies and trout, they're trying to evolve to eat mayflies. Mayflies are much older than trout evolutionarily, right?
Robert: Oh, yeah, ages and ages older. Some scientists call it the oldest surviving winged insect on the planet. And we know just as one reference point that a guy now up at Harvard found an impression of a mayfly in Iraq that they determined to be about 300 million years old and that was just when the dinosaurs were coming into their own. So, these are likely the oldest and among the most primitive creatures on the planet.
Tom: And ecologically, how important are they in the whole trout stream or trout lake ecosystem?
Robert: Well, I should warn you that one of the cornerstones of my piece is I didn't know much about this apart from the predatory aspect where I tied, you know, nymphs and mayflies to catch fish. So, I knew a little bit about them and I knew a little bit about the cycle but all of this is fresh to me. And it's very startling because it turns out that mayflies and other aquatic insects like stoneflies, caddisflies, and so on, in freshwater around the world form one of the...really, the anchors of our food chains, okay? Multiple food chains are anchored by these aquatic insects.
Then it turns out that they are part of something that I can now talk about without feeling sort of hippie-dippie because it's so grounded in science, which is ecology, local ecologies on local streams, all over the place, in rivers, in lakes rely on mayflies to keep continuing to exist. And think of these ecologies, these local ecologies as fine machinery, so it doesn't take a lot to realize that it's not just fish that are eating them but amphibians, birds, bats. And then, of course, there's the larger critters and creatures that eat those things. Bears eat fish. If the fish aren't there, the bears aren't gonna have something to eat, and so on and so forth. So, they're really fundamentally important to the various ecological systems in the world.
Tom: I saw something this year that I had never seen before. It was a really heavy mayfly hatch, Hendricksons hatch, and the geese were gobbling the mayflies, which I had never seen before. The geese were out in the middle of the pool just gobbling those mayflies down. Didn't bother the trout a bit either.
Robert: That's funny. Well, it makes sense because you just have this torrent of protein and so many creatures rely on them, and then other creatures, of course, rely on the ones that eat mayflies.
Tom: And, Bob, I know that...people like me who have fly fish for a long time and have been observing these things seem to sense that we're not seeing as many mayflies, we're not seeing as many hatches, we're not seeing the same diversity, we're not seeing the quantity of mayflies. And I know you explored this in your piece in great depth, but tell us a little bit about some of the threats to these really important orders of insects.
Robert: Well, let me start with the fading of mayflies. We know for a fact that on various freshwater bodies, streams, rivers, lakes, ponds, that mayflies are fading from particular bodies of water. But one of the things that's really interesting here is there's almost no global data or even national data or even state data to chart that systematically. And so, we're sort of stuck in this round where there's clearly a larger pattern going on but the degree to which they're fading is unknowable at this point because of lack of data. Now, one of the things I've had the benefit from is I get to speak with these incredible, disciplined biologists, entomologists, and so on. Top shelf people, some of them focusing on insects in general, some of them focusing on mayflies. And I attended a conference last summer about mayflies and stoneflies, two different organizations but they had a joint virtual meeting.
And it's really interesting listening because there are scientists now around the world at this meeting and just from the science that I'm reading, who are sounding the alarms about their local waters, but there's nobody that has brought it all together to the degree they can and made sort of global pronouncements. But it's happening, it's very clearly happening all over the world, and I'll just give you some examples from my continuing research. Down in Patagonia, mayflies are disappearing. The highlands of Angola, the Cairngorms in Scotland, the chalk streams in England, in Japan, or just, of course, in the mega drought in the West. It's just an amazing phenomena, it's really frankly a little depressing. There are problems with mayflies.
So, you asked about some of the elements behind this and I think that's well-known, it's just not known how it applies broadly. So, for example, some of the simple things are development. If there's a development near a stream and the dirt and silt runs off, you have a problem and mayflies are going to be affected. Agriculture, there are types of pesticides that have become the most frequently used pesticides in the world in the last 30 years. Neonic is the short-term for them, they replicate the effect of nicotine. And they use them in fields in agriculture and yet, it's, I don't know, thousands of times more lethal to mayflies and other aquatic insects than it is for the bugs that the neonics are intended for. You have salt running off from roads, and that wipes out freshwater aquatic habitats, silt, and so on.
And then you have the harder-to-pinpoint but very real effects of climate change. So, if the water becomes too warm, there might still be mayflies there but a lot of times, there are invasive species or other invasive species move into the water and eat the mayflies and wipe out or hurt the populations. If there's forest fires or mega-droughts, that's obvious how that can have an impact. But forest fires lead to ash and silt in the streams and wipe out the shade that we all know we need, you know, for a healthy freshwater stream to support trout. So, I mean, I could go on and on from what I'm learning, but those are some of the elements.
Tom: Yeah, it's a death by 1,000 cuts, obviously, like a lot of things. How dangerous are herbicides? And I asked that, because I see an increasing tendency to spray roadsides with herbicides. In fact, even in Vermont, which you think of as being a fairly environmentally aware state, they use herbicides along the roadway, sometimes, you know, 20 feet from a trout stream. In fact, I've had to call the state and tell them not to spray herbicides along my guardrail because I live on a trout stream, I didn't want it there. Do you know you know if there are any dangers to mayflies?
Robert: Yes, the danger is, is very, very real. But I can't articulate it, in part because I'm just getting a grip on the science. But there's a growing body of evidence going back to these neonics, the class of pesticides. There's a growing body of science that confirms the effect on freshwater streams and aquatic insects. So, yes, it's a real threat without question, but I can't speak deeply to it.
Tom: Yeah, yeah. How persistent are the neonics? Because we know that they're...well, we know there's lots of documentation about honeybees being devastated by neonics. How persistent are they?
Robert: It's funny, I was just looking at some science about that and their various claims that it's persistent, but I think that the research is still going on. It's interesting, the EPA is studying the effects of neonics but they keep putting off the endpoint of when they're going to report. So, I think right now they've got some conclusions that they're going to release in 2024. But it's a fascinating and a little bit terrifying thing. There's a book that I'm working my way through that's just really well done by a biologist in England named Goulson, the book is called "Silent Earth." And I mentioned it in part because it's meant to echo Rachel Carson's seminal book called "Silent Spring," which looked at DDT and other pesticides, and there are some people who argue that we're entering another era that's going to be equally perilous for us.
And, you know, the funny thing is, Tom, is that I'm starting to see the science literature, a recognition that when you bring what they call stressors together, so if you have the neonics and you have the development all over the world because there's so many more people than when we were young men, and that's a very real effect on everything around the world, all the freshwater. But when you have that, the development and so on, the neonics, and you have the climate change, the effects of climate change, which are still, of course, you know, they're poorly understood. But when you have those things together, it can create a really lethal environment.
Tom: Yeah. You know, it's interesting you brought up that book because I've been working my way through a book called "Beyond Silent Spring," which is about the proto-environmental movement in the '50s, '60s, and '70s. And it made me aware of the fact that today, we don't have any Rachel Carsons, we don't have any William O. Douglases, we don't have any Stuart Udalls in positions to really bring this to people's attention like we did in the '60s and '70s. You don't see it.
Robert: Well, we could talk at length about that phenomenon. But one of the things I've noticed in the world of journalism, having been at the Post for so long is that the dynamic where people or readers...okay, the great middle of the United States, the center left, center right, and so on were so attuned to environmental issue, political corruption, follow the money, all that stuff. And that's just become so fragmented now, and a lot of it is because you have these forces out there, some of them the energy companies, some of them the makers of pesticides, you know, others are just political radicals who spew out disinformation so that, you know, people younger generations than ours sort of...there is no clear message that's coming through. It's tough. I'm glad to see that people are starting to accept climate change, for example, because the evidence is so strikingly obvious at this point. But there's still a huge cohort of people that are fighting a rearguard action against measures to, you know, stem the tide, so to speak, and know?
Tom: And, you know, again, going back to the '60s and '70s, there was bipartisan support for these environmental laws that were passed, Clean Air Act, Clean Water Act, Wild and Scenic Rivers, it was bipartisan and you just don't see that anymore.
Robert: No. Again, don't get me started...
Tom: Yeah, we should get off the politics and talk about bugs.
Robert: It's a seriously bummer thing. The one thing is, ultimately, while we're talking about mayflies, the fish that I'm frying here is ultimately, the message of the mayflies. That's the sort of theme, the message of the mayflies. And the message is, of course, ultimately, to me, is about freshwater.
Tom: Yeah, yeah. So, tell us some more eye-opening things that you discovered about mayflies in your research.
Robert: Well, we talked about that they're likely the oldest winged insect on the planet that's surviving and that's remarkable. In a way, I'm super interested in the cultural roots of mayflies. Mayflies had been having an effect on the world for thousands of years and...excuse me, mayflies have been having an effect on the world for thousands of years on artists, writers, poets, and so on. And for some reason, I feel like that's worth knowing and exploring because when mayflies fade, it's not just a bug and it's not just an ecosystem or science. It's the way we feel about ourselves and about the world and how we interpret our lives and that, to me, is very important.
So, for example, I found that the first reference to them that we know of was "Epic of Gilgamesh," which is a Mesopotamian poem and one of the world's oldest pieces of literature. And it turns out that Aristotle dubbed the insect ephemeron and you have people like poets, like, there's a Chinese scholar from, I guess, maybe 1082, I'm looking at my piece here and Su Shih used the idea of mayflies as a metaphor because, of course, we...I suppose most of us know that mayflies live almost, you know, maybe 99% of their lives underwater, 99-plus. And when they emerge, they not only become this stunningly beautiful creature, that creature only lives for 24 to 48 hours in most cases.
And it doesn't eat, its mouthparts don't even work, and its sole mission is to mate. So, when you see mayflies kind of bobbing, it's almost like a mating dance and they're trying to find mates, you know, with a certain urgency because they're gonna die very, very quickly. And this Chinese scholar, Su Shih wrote, "We exist no longer than mayflies between Heaven and Earth." That's pretty good, you know? And then you've even got Albrecht Durer who was the remarkable Renaissance painter, who included a mayfly at the feet of the Virgin Mary in one of his paintings. So, yeah, that's pretty cool. It just shows the effect they've had on us humans over many years.
Tom: What else did you discover about the science around mayflies, about just their lifecycle and...?
Robert: Well, we know that they live, as we said, most of their lives under the water. In those early stages, I found having looked at them through a microscope and I recommend this to anybody, when you look at them through a microscope, they're kind of like a mini sci-fi monster. They're just...I mean, I literally laughed out loud when I saw it and the naturalist, the water specialist I was with heard me laughing and she says, "Isn't that cool?" Because it's just hard to believe how they've got this outer skeleton and they just look horrific and somehow, they shed that and they become these beautiful things. And so, that's kind of cool. There's probably 3,700, maybe as many as 4,000 that we know of living around the world. I found that Indiana, my home state, has one of the largest mayfly populations west of the Appalachians which...
Tom: Wow.
Robert: Yeah, that's kind of interesting. I mean, Indiana is not exactly a trout state and so on, and yet, they've got this big population. We know that state the obvious, the presence of mayflies is a really good sign. It may not be the same populations they used to have but I went to a local stream here in Arlington, Virginia, which is a densely developed, you know, sort of quasi-urban area just outside Washington DC. And lo and behold, there was a Blue-winged Olive in one of the streams, and that's kind of a cool thing because the stream is, in many ways, a stormwater stream to make sure that houses don't flood. So, there's just some of the details.
Tom: Are some species of mayflies more tolerant of these environmental insults than others, do you know?
Robert: There are some that are much more tolerant. So, among them is a large mayfly called the Hexagenia, one of the classic mayflies family. And I discovered this because I was looking at some science, really interesting stuff, and these biologists were testing the water near Lake Erie in the northern Midwest. And this guy named Phil Stepanian discovered that you could actually see mayflies on weather radar. And so, these giant hatches, you know, just showed up in these giant clouds and that kind of radar imagery had been used to track migrating birds, so they thought, "Well, let's do this for mayflies." They did it and they recognize that they could take the images from the past once they figured out what they were looking for, and compare past clouds to current clouds. And the thing that was so troubling is that the Hexagenia, these giant clouds were diminishing year by year. And the reason it was doubly troubling is that the Hexagenia, which is a burrowing mayfly, borrows into the silt at the bottom of the water, are among the strongest mayflies out there. So, there was sort of a double whammy of concern.
Tom: But we don't have any idea know, we don't really have a broader understanding of which ones are more tolerant and which ones aren't...?
Robert: No, no, no, they do, they do.
Tom: They do?
Robert: Yeah, yeah, yeah, the entomologists could probably...and I don't have it at the ready, but no, there are definitely some that are...well, you raise a really good question. There are definitely some that are more tolerant and less tolerant. And we know that because there's a method that is beginning to spread around the world. The shorthand is called the EPT which is the initials of the Latin names for mayflies, stoneflies, and caddisflies. Okay? Well, they use EPT to train biologists and will use EPT to check the quality of the stream, and it's pretty cool. There's a class every summer in June in the highlands of North Carolina and a professor from North Carolina has been teaching this boot camp to entomologists for many years now, to train them on how to use these bugs to test the water quality of the streams. And of course, depending on which mayfly you're looking at, it's going to be more tolerant or less tolerant, so they have a pretty good grip on that.
Tom: Is it the ratio of one to the other or are they just looking at all of them together?
Robert: Oh, no, it's the ratios, it's the populations, it's the change over time in the populations that they're using.
Tom: Fascinating.
Robert: It is, actually. They sometimes use the phrase biosensors, which makes really put them into a different category. We think of mayflies as, "All right, what do I tie on to catch my fish?" And it's a glorious thing when you get it right even if, you know, like in many cases for me, I'm the blind hog that finds an acorn by the log, right?
Tom: Yeah, me too.
Robert: But when you think of a mayfly as a biosensor when I learned this, well, suddenly, it's a strange and interesting thing. And this is part of the reason I decided to focus the first story in "The Washington Post" about mayflies is that it changes your whole framework for looking at the water that you're on. Suddenly, you realize that the mayfly...yes, it's a bug for our predatory practice of fly fishing and I say that with pride. But it's also a biosensor that's sending a message, the message of the mayflies about the quality of that water. And many of us are fishing on streams now.
For me, I sort of feel like I'm not sure this is true, but the Gunpowder River northwest of Maryland is a wonderful, gorgeous trout stream, tailwater, and I'm almost sure that the hatches have just tailed off over many years. I mean, I used to catch sort of big fish there in the mid-90s and the fish are smaller and the hatches are, you know, less complete. And so, when you see a mayfly on the Gunpowder or, you know, the Hazel River and the Shenandoah or the west branch of the Delaware River, or wherever you're fishing out west, there's some streams in Utah that are depleted. For example, you could see the mayflies that are there and you could say, "Oh, that's a biosensor, I wonder what it's telling me." It's just a different way of thinking about it.
Tom: Yeah. Yeah, it is, it is. So, we know that mayflies and other insects are in trouble. We know they're important to the ecosystem and to us as trout anglers. What can people do? What can an individual do to help reverse this decline?
Robert: It's a fantastic question and I'm exploring it in my homework. So, as I do more homework on this stuff, I'm seeing, Tom, that there are scientists who are sort of coming down from the ivory tower and offering suggestions. And the first one in a recent report was that you can, I'm reading directly from it, convert lawns into diverse natural habitats. And I know this firsthand because about five years ago, my wife, Amy, started asking me did I mind if we shrunk the lawn and I didn't really know where she was going with it and I'm like, "Yeah, sure, if you want." And over the last five years, she's slowly crowded out our grass, we still have a little bit and it looks kind of nice, but it's dominated by native plants from Virginia.
And as a result, we have swarms of bees all summer long now and the monarch butterflies stop and lay their eggs on the various milkweed plants and we have all these blossoms, you know, from these native plants that sort of cycle through the years. So, starting in May, we have some and then there's different ones in June. Any gardener will recognize this, I'm not a gardener. But at any rate, it's a really cool thing to do even if it makes us look like the untidy people in the neighborhood. People have started stopping by, like, the neighbors will stop and I see them out there pointing at various things and some other gardeners approach my wife and ask, you know, how she's doing certain things. And it's a really cool thing that people can do.
And what it does is, A, you're not using pesticides and herbicides, and B, you're giving habitat for these insects, which...look, it's a global crisis for insects, not just mayflies but regular insects in general. There's a concern that we may be, you know, in this sort know, this apocalyptic kind of, you know, death by a thousand cuts to use your phrase. So, anyway, that's one thing that you can do. Limiting the use of exterior lighting. Lights screw up insect patterns and drive them away and it's, you know, not a good thing for insects. Soap runoff from washing vehicles and building exteriors and so on isn't a good thing because all of that stuff ultimately makes its way to streams and the soap can be poisonous to aquatic habitats. And then, I don't know what you and I and guys like us can do about this, but the salt on the roadways is really hurting aquatic habitats. So, those are a few of the things that, you know, maybe you can lobby your local municipality to find alternatives to the salt.
Tom: Yeah, I found the problem is if they don't use salt, they use sand, and it increases siltation in the river.
Robert: Yeah, it does.
Tom: And nobody wants unsafe roads, right? So, that's a real dilemma, that's a real dilemma.
Robert: It is, it is. I mean, part of the reason we have more roads and more traffic on the roads is that the population, it's just grown so much over the last 50 years. And you have to have trade-offs, you have to make sure that things are safe. So, you know, that's way beyond my paygrade to try to sort these things out. One of the things that the scientists talk about...and this is sort of really micro, but they talk about becoming educators and ambassadors and advocates for insects. So, you know, those are some of the things they talk about.
Tom: You know, it's always best to try to multiply the force behind things we want to happen. What organizations are really working toward reversing this decline of aquatic insects?
Robert: Well, there's a really interesting group called the Xerces Society. It's X-E-R-C-E-S. And then there's a guy there, Scott Black, who keeps showing up on the science paper, so he's the real deal and they're real strong advocates for insects. You know, the sort of obvious example, Trout Unlimited, they just got a $40 million grant from the Forest Service...they've got a $40 million financial aid from Forest Service over the next five years to protect and repair headwater streams. And the idea here is not just to help with trout, but also to help with clean water for people downstream. And those are a couple of the big organizations. There's lots of various conservation groups that are really dialed into this stuff and various organizations that focus on American rivers. So, those are some of the groups and it's an easy thing to know, if someone wants to become active, to find a niche for themselves.
Tom: Yeah, and there's probably local organizations that are also working towards those ends that people should investigate.
Robert: Tom, there are, and one of the things I've discovered in my homework here, it was something I never gave any thought to, is citizen science. So, in Northern Virginia, there are multiple efforts by municipal authorities to track the health of freshwater streams, and they rely on citizen volunteers to put on their boots and get in the water and sign the rivers and streams and creeks, you know, for the kind of bugs that can talk to the issue of whether the streams are healthy or not. I had never done that until this year...pardon me, until last year, and it's really gratifying, it's illuminating. I'm not sure how it all adds up but, you know, it's something that people can do to contribute.
Tom: Yeah, yeah. Well, mayflies are certainly fascinating creatures and, you know, we should all do everything we can to help their populations. I mean, if you have a lawn and you're putting pesticides or herbicides on it, shame on you to have green grass on your lawn.
Robert: Well, I'll tell you, it's even with leaves. Not all, but many of our neighbors gathered their leaves up, sometimes using gas-powered, you know, annoying blowers. They then haul the leaves to a landfill so that their yards don't have leaves. But the irony is, leaves are great for insects and they're great to fertilize the grass but you mow it up. So, you know, I'm looking out my window now and unlike all the other yards, there are some residual leaves in the beds and on the grass and it's a good thing, it's not a bad thing. But the energy that it takes to take that stuff away, and then it's going to sit somewhere and as it decomposes, it's not going to be helping where it could help if it were decomposing in your yard.
Anyway, It's a tough thing. You know, you don't want to be gloomy about fly fishing because it's such a wonderful pursuit. And yet, I've found that this homework that I've done has caused me to sort of think about...and I haven't come to any hard conclusions on anything, really, except that I should probably try to, you know, watch what I do a little bit, be a little more purposeful and thoughtful about these kinds of things. The leads and, you know, how far I'm going, do I really need to travel across the country to fly fish? Or can I fish in my own backyard, so to speak, or in my region? And I don't know, everybody has to come to whatever conclusions they come to themselves, but it's good to be thoughtful about it.
Tom: Yeah, I mean, if we're going to enjoy this sport, we need to give back, we need to give back to the resource, not just take advantage of it and that's something that everyone should be doing in some small way.
Robert: I agree. Maybe, Tom, in a larger sense, we can catch a few or several fish and let the know, just scale it back a little bit and not catch so many fish or not handled the fish so much or know, maybe take 5 or 10 or even a half hour and actually just sit still and look at what's underneath the rocks and, you know, the mayflies and the other aquatic insects that are there. I don't know. I mean, I don't want to get fancy dancy on this stuff but I think that by actually changing some of our behaviors, at least for myself, I've slowed things down on the streams and it's really kind of cool. There's stuff that I didn't notice before because I was so intent on catching more fish, whereas I could still catch fish in different ways and at the same time, now I have this added benefit of kind of looking around.
Tom: Yeah, I mean, there's a real movement starting now for people to not catch as many fish, you know? And I think that's a good thing. I mean, it's not going to save the environment but it is going to make fishing better for other people if we don't harass so many fish, you know, in the short term.
Robert: Right. So, for part of my homework on a piece I was writing for "The Drake Magazine," I was on the Green River, an incredible fishery in Utah, and I saw a guy, obviously very, very well off, put a drift boat, it's like a private drift boat into the water, and he tied on what would have been like...I mean, even larger than a bobber that I used when I was a kid when I first started fishing. And he obviously had nymphs on, like a brace of nymphs underneath it. And I just thought, "Well, everybody's got to go their own path, but that's not something I would ever do." Like, why fish with a bobber? Yeah, you're gonna catch fish but what is that about? Anyway, whatever, now I'm ranting.
Tom: That's all right. You can get up on your soapbox here, that's what we do sometimes in the podcast. Well, Bob, I want to thank you for taking the time and sharing your knowledge with us and I applaud you for continuing your education and your research on this issue because it's important, and maybe in a year or so when you get further along, we can have you back and explore some other topics.
Robert: That would be an honor. Thank you.
Tom: All right, thank you. We've been talking to Robert O'Harrow of "The Washington Post" about mayflies. And thanks again, Bob, and hope to talk to you soon. Thanks for listening to "The Orvis Fly Fishing Podcast" with Tom Rosenbauer. You can be a part of the show. Have a question or comment? Send it to us at in the body of an email or as a voice attachment. You can find more free fishing tips at