Anglers interested in catching more trout have long been encouraged to “think like a fish.”

Robert Younghanz suggests thinking like a bug might help more.

“I think it’s ironic that people aren’t comfortable with aquatic entomology simply because it’s really the fulcrum of everything we do in fly-fishing,” Younghanz said. “You can be a horrible caster and eventually work it out. You can eventually learn to decipher fish feeding behavior. You can learn to read water. But, ultimately, without insects, we don’t have fly-fishing. If you want to go out there and be successful and not just guessing, you need to know your bugs.”

Going by the title of “The Bug Guy,” Younghanz describes himself as an aquatic entomologist, fly-fishing guide and instructor working through the Angler’s Covey in Colorado Springs. He’s also the “star” of a new double DVD, “The Bug Guy: Entomology for the Fly Fisher,” designed to take the fear out of fishing.

“It’s the hardest thing to learn in fly-fishing,” Younghanz said. “It’s funny how it gets dismissed because people are intimidated by the discipline. Yet, when they take the time to go out there and learn it, their fishing production goes up exponentially. That’s proven all the time.”

As a first-time presenter at last weekend’s International Sportsmen’s Expo in Denver, Younghanz drew crowds throughout the weekend as he walked anglers through the basics of bugs. But the aquarium set up at his booth proved to be the bigger showstopper, crawling with impressively large insects known as Hesperoperla pacifica, a medium brown stonefly he pulled out of the South Platte River near Deckers before dawn on the cold winter morning the convention got underway.

“This is one of your first big stoneflies that’s actually going to emerge across the United States, as early as March. But people don’t know about it, even though it offers a chance to get into some big fish,” Younghanz said. “Last spring I went out to the South Platte at Deckers and everyone was fishing these little size 22-24 midges, teeny stuff. And I walk out with a size 10 black Pat’s Rubber Leg because I knew these guys were moving, and I caught the largest trout I’ve ever caught on the South Platte other than the Dream Stream — a 7½-pound rainbow that was almost 26 inches.”

Younghanz isn’t promising trophy trout to fishermen. But the basic aquatic entomology he preaches offers something even more important: confidence.

From the outside, it can be a tough sell. Most fly-fishermen don’t get into the sport because of a love of bugs. Instead, they see the artistry of the cast, the glamour of landing a large fish on delicate tackle, often without pausing to consider the steps that get them there.

“What usually happens with guys is they run out of options, because they don’t know their mayflies, their stoneflies, their caddisflies, their midges. They don’t know what goes through complete metamorphosis and incomplete metamorphosis. They don’t know the difference between a larva, a nymph, an emerger and an adult,” Younghanz said. “And you’ve got to be comfortable with the nomenclature. You’ve got to be comfortable with the science. I always say, trout don’t speak Latin, but at the same time, you probably at least want to know your aquatic orders at the streamside. If you can do that, you’re going to probably know more than 90 percent of the people out there.”

Younghanz has done the work. He has flipped over the rocks, seined the river, spent hours over a microscope and studied the stages of insect life that make up a trout’s diet during different seasons and at different times of day. And while he admits to a degree of fanaticism, other anglers can learn from his efforts.

“My whole approach is that there’s no luck in fly-fishing. It is a complete science,” said Younghanz. “If you approach it and do good science, turn over a few rocks, maybe get a seine … then if you walk off the water after a tough day, at least you know you did what you should have done, which is to go and see what forage is out there for the fish.

“That gives people an opportunity to walk off the water with a certain level of confidence and say: ‘You know, maybe I didn’t catch a lot of fish today, but at least I felt like I did what I could. Maybe it was just one of those days.’ ”

Scott Willoughby: 303-954-1993 or swilloughby@denverpost.com

Tips from “The Bug Guy”

Known as “The Bug Guy,” Robert Younghanz gives his best pointers for fly-fishing:

Fishing a new river: No. 1, check with the fly shop and get local information.

Beware: Of information from some guy who has been sitting behind the counter and hasn’t been on the water for three months. You want to talk to guides who are out on the stream.

Seasonal hatch charts: They can be helpful. But a lot of shops don’t stay up-to-date.

Seine the river: Generally you don’t want to use that net for the deep, slow pools. You typically want to seine the riffles, or anywhere you can move the rocks.

Most important: Separate fly boxes into aquatic orders. I have a mayfly box, a stonefly box, a caddisfly box, a midge box, worms and eggs, and crustaceans, and I have terrestrials. I immediately know that I’m going to the aquatic order that I want.

Flies: I probably carry 5,000-8,000 flies to the river just for my own peace of mind, but I pretty much use the same 15 all year.

One dry fly for the rest of my life: I could not live without a parachute Adams. It covers all orders. One nymph? A flashback pheasant tail. Most important lake fly? Callibaetis.

Best time to study bugs: If you want the best representation of biomass out there, probably April or May. You’ll miss a few things, but May 1 is a hot time to look for bugs.

More info: robertyounghanzflyfishing.com