Size M You wouldn’t guess at the shape or a hatch, so why are you guessing at T rout survive by becoming efﬁcient feeders. They constantly adapt to the available food sources and key in on the ones that are most prevalent at any given time. Each bug they eat is positive reinforcement that encourages them to look for more of the same. As a result, ﬁsh become selective and ignore other food items in the drift. Fly anglers who can identify the food most available to trout and match a ﬂy pattern to it greatly increase their chances of success. Most experts agree that size is the most critical aspect of matching the hatch. But surprisingly, experienced ﬂy ﬁshermen misjudge ﬂy size more often than not. Get the size close, and you will catch a few ﬁsh. Use the right size ﬂy, and you have a better chance at catching a lot of ﬁsh. 40 I AMERICAN ANGLER WWW.AMERICANANGLER.COM Matters by Troy Pearse color of the natural insect during the size? Here is how to get it right. COREY HHKRUITBOSCH Size Survey Last summer, I gave a presentation on local hatches at the 2010 Western Idaho Fly Fishing Expo, during which people were asked to estimate the size of nine bug samples and three ﬂies. All participants in the study were experienced ﬂy ﬁshermen and ﬂy tiers. The bug samples were in individual glass vials of isopropyl alcohol, and the ﬂies were mounted on foam. Results of the survey showed that 72 percent of size estimates were wrong, and 19 percent were off by two or more sizes. The best any one person did was accurately size half the samples, and that person was a professional ﬂy tier. One common pattern noted in people’s guesses was having a preconceived notion of the expected size of a bug. They expected midges to be tiny, so most guesses were too small for a size 16 midge sample. Similarly, they did not expect the net-spinning caddis to be so large, so they guessed the WWW.AMERICANANGLER.COM typical size of 14 when the actual insect was a size 10. Part of the confusion is that there isn’t a standard for hook sizes (see sidebar on page 42). Being off by one hook size may not sound signiﬁcant, but it can often make the difference between a trout accepting or rejecting your ﬂy—especially on pressured waters. There is a 25 percent difference between the shank length of a size 18 and size 16 dry ﬂy hook, a difference that trout will notice. Measuring Bug Size Most ﬂy ﬁshermen wouldn’t dream of using the wrong type and color of ﬂy during a hatch, such as a Tan Caddis imitation during a BWO hatch. Yet they will routinely and inaccurately guess at the size for their ﬂy. The key to selecting the correct ﬂy size is measuring the bugs that ﬁsh are eating and then selecting a ﬂy that matches. It’s that simple, MAY/JUNE 2011 I 41 TROY PEARSE but you do need two things: a reference tool and a bug sample. Here is where most anglers fail. One can often tell the type of a bug as it ﬂoats by 20 feet away and get a good idea of the color, but until you have an insect in hand, you are only guessing at its size, and as demonstrated by the survey, most likely guessing incorrectly. If bugs are hatching, try to collect one from the surface ﬁrst. Look in back eddies for drowned naturals, or wade out quietly below rising ﬁsh and grab one. Using a piece of mesh—such as a mesh bag that ﬁts over a landing net—makes it much easier to scoop bugs from the surface. If nothing is currently hatching, then look around for bugs onshore in bushes, underneath leaves, or caught in spiderwebs. Turn over rocks near shore and see what nymphs are present. Better yet, use an insect collection seine and gather a sample from a rifﬂe that is one to two feet deep. Put the seine on the stream bottom and kick over rocks directly upstream. By collecting a bug sample for ﬂy selection, you have taken a huge step forward and are now ahead of most other ﬂy ﬁshermen out on the river. Hold the bug up to different ﬂies in your ﬂy box until you ﬁnd one that matches the size, shape, and color. Make sure the body length of the bug matches the ﬂy (excluding tails, wings, antenna). For dry ﬂies, pay particular attention to the color of the underside of the bug because this is the color that ﬁsh will see most. It is very helpful to know the hook size that matches the bug, so that you can communicate that size information to your ﬁshing partners, make entries in your ﬁshing journal, and later tie or purchase ﬂies that match the hatch. To make measuring bug size easier, I created a bug/ﬂy size chart called the Bugometer. (See page 43.) Simply hold your Hook bug or ﬂy up to the chart, and you have the correct size. Sizes Manufacturer in the chart are based on the Size Differences hook-shank length of Tiemco standard, 2XL, and 3XL hooks. I have been using the Bugometer for a couple of years now and have found it Having a variety of sizes in each pattern is a cornerstone of matching the hatch. In this case, the larger size 12 (2XS) ﬂy better matches the netspinning caddis than the smaller size 14 (2XS) does. indispensable for choosing the right size ﬂy. There have been many times on the water when I was getting refusals to the ﬂy I was using. But when I took a few minutes to capture a natural, measure the size, and changed my ﬂy to match, I immediately started catching more ﬁsh. The scale reproduced on page 43 is the exact size of the Bugometer, which you can photocopy, laminate, and keep in your vest to measure bug size. You can also purchase a transparent plastic version online through DryFly Innovations.com. (Editor’s note: The author originated the Bugometer but allows another party to manufacture and market it. He does not receive compensation for sales). Bug Size Variations The average angler is able to recognize a hatch situation and can tell that ﬁsh are taking mayﬂies, caddis, or stoneﬂies, but too often that is the extent of their analysis. They open their ﬂy box and choose a ﬂy without knowing the actual size of the hatching bugs. This works sometimes because there are typical sizes for the hatch, such as size 16 for a pale morning dun (PMD), size 20 for a blue-winged olive (BWO), or size 4 for a salmonﬂy. But the problem is that each bug Hook Size Varations Hook Style Size Differences 42 I AMERICAN ANGLER ONE REASON PEOPLE GUESS SIZE WRONG IS THAT THE SHANK LENGTH OF A GIVEN HOOK SIZE ISN’T consistent across hook manufacturers and styles. A hook shank can be standard, short or long, and there are general conventions about what style of hook is used to tie different patterns. For instance, scuds and caddis pupa are often tied on a curved 2X-short hook; mayﬂies on a standard-length hook; grasshoppers and other large terrestrials on a 2X-long hook; and stoneﬂies on a 3X-long hook. This means a size 10 Royal Wulff is one-third shorter than a size 10 Stimulator because the Wulff is tied on a standard shank hook, while the Stimulator is tied on a 3X-long hook. Similarly a size 16 Z-Wing Caddis Pupa tied on a curved 2X-short hook is 25 percent shorter than a 16 Elk-Hair Caddis tied on a standard-shank hook. Although hook manufacturers use a common size numbering scheme, there is no standard for hook length. For example, the shank length of a size 16 Dai-Riki and Mustad hooks are 25 percent smaller than the same size hook from Tiemco and Daiichi. These complications make it essential that you collect a sample and match it directly to the ﬂy you intend to use. WWW.AMERICANANGLER.COM Common Sizing Mistakes The Bugometer DryFlyInnovations.com BOTH BY TROY PEARSE hatch is different, even within the same species. The insects aren’t always the same size, which means that ﬂy-size guesses based solely on typical insect sizes or hatch guides are often wrong. For example, many mayﬂies are larger earlier in the hatch season and grow progressively smaller over time. A PMD may be a size 14 when the hatch starts, a size 16 a few weeks later, and a size 18 by the end of the hatch. Similarly, BWOs are typically larger in the spring, smaller in the fall, and show a similar size reduction through the hatch. This variation in size isn’t limited to mayﬂies; the size of midges and stoneﬂies also varies through the season, year-to-year, and among different rivers. The size of salmonﬂies hatching may be a huge size 2 (3XL) one year, but be a size or two smaller when they start hatching upriver or in the following year’s hatch. People also tend to think of a nymph as always being the same size as the adult, but the size of nymphs continually changes through their life cycle. A Skwala stoneﬂy nymph might be a size 8 (3XL) when it hatches in April, but in January and February, the nymph is a size or two smaller. It is important to remember that the size of bugs changes over time and location. You may have had the right size ﬂy last week, but that doesn’t mean it is the right size ﬂy today. Check the water to see what ﬁsh are feeding on before choosing a ﬂy. LEFT: Preconceived notions of insect sizes are often wrong, as this size 16 midge shows. Many anglers just assume midges will be size 18 or smaller. And these bugs are often bigger in spring than in fall. RIGHT: Skwala stoneﬂies are typically a size 8 (3XL), but the nymph can be much smaller prior to maturation. TOP: The Bugometer scale. Here are ﬁve common mistakes anglers make when sizing ﬂies, along with suggested remedies. 1. Guessing at Size The biggest mistake people make is guessing the ﬂy size instead of measuring it. The simple solution for this is to catch a bug and measure its length, and then select a ﬂy that matches. moving a couple miles upstream or downstream can result in a different size hatch. Try a smaller dry ﬂy or a larger nymph—or better yet, collect a new sample and verify its length. While catching your new sample, look for other food sources that ﬁsh are eating, such as a spinner that is ﬂush in the surface ﬁlm. 5. Hook Size Differences 2. Including the Wing Some people mistakenly include the wing or tail in the length and choose a ﬂy that is too large. Wings on caddis are usually much longer than the body. Make sure to turn the bug upside down and check the body size. 3. Secondhand Information Too often people choose a ﬂy based on secondhand information, such as a ﬂy-shop recommendation, a hatch chart, or a ﬁshing report. These are all good references, but they aren’t always going to match what you ﬁnd on the river. Be ready to verify and switch pattern size if the ﬂy you ﬁrst use doesn’t produce. You bought or tied a size 16 ﬂy expecting a certain size. But the length of a size 16 ﬂy can vary signiﬁcantly, depending on the style of hook and who made the hook. Before you tie on that ﬂy, make sure to double check the actual length—you might be surprised to ﬁnd out it is a size larger or smaller than you expected. See the sidebar to learn more about hook size differences. I 4. Bug Size Changed n their book Selective Trout,t Swisher and Richards state, “The ﬂy ﬁsherman who knows what is hatching and has realistic imitations will consistently be more effective than the angler relying on trial and error methods.” Fly selection doesn’t have to be a guessing game. Take a few minutes to capture a bug, measure its size, and then choose the right size ﬂy, and you will ﬁnd yourself saying more often, “There he is!” Last week you were killing them on a size 16 Yellow Comparadun ﬂy pattern during the PMD hatch, but this week you’re getting refusals. Remember that bug size changes over time and that just Troy Pearse is the originator of the Bugometer scale, and an avid ﬂy ﬁsherman who works in Boise, Idaho, as a software engineer. WWW.AMERICANANGLER.COM MAY/JUNE 2011 I 43