Spring Brings Skwalla Hatch
The appearance of big skwalla stoneflies in March, as the first significant fly hatch of spring, quickly grabs the attention of Montana trout and trout anglers, both hungry for action after the long winter.
The skwalla hatch has reached almost legendary status in recent years, especially associated with the Bitterroot River, where the bugs make their earliest debut.
But skwallas are by no means the only hatch of spring. In fact, for every red-letter skwalla day mentioned in my fishing logs, there are at least as many other great fishing days in March and April that featured a different fly hatch.
Early spring actually is a smorgasbord for fish, offering a variety of stoneflies, mayflies and caddisflies for trout to eat, and fly-fishers to imitate.
Besides skwallas, three of those hatches are of particular importance to anglers, according to local fly-fishing guides.
They are, in order of their seasonal appearance, the blue-winged olive mayflies, gray drake mayflies (also known as the western March browns), and the grannom or “Mother’s Day” caddis. At any given time, on any given stretch of the Bitterroot, Blackfoot, Clark Fork or Rock Creek, feeding fish may become extremely selective to one of those spring hatches. So a fly-caster should be prepared to match the fly that happens to be in favor at the time.
Then there are those incredible spring days when there are so many flies available to the fish that they abandon any semblance of caution, or discriminating taste, and greedily snap up anything that floats past.
“It’s one heck of a good time of year to be a fly-fisherman,” said John Gould, a guide and professional fly-tier who works at the Missoulian Angler fly shop.
“There are days when it’s a free-for-all,” he said. “An overcast day after five or six days of sunshine - it’s a treat to be out there.”
Following closely on the heels of the skwallas is the blue-winged olive hatch.
“Usually about mid-March you’ll start seeing them,” said Gould. “Then you’ll start seeing places on the river where fish are keying on them.”
Most fly shops offer a wide selection of blue-winged olive patterns.
“We’ve got nine different patterns for them,” Gould said. “But the ones we use most are a high-rider parachute and a cripple/emerger.”
The most effective olive patterns generally are size 18 or 16. The flies start out smaller in the early season and get progressively larger, Gould said.
Surprisingly, trout occasionally target the tiny olive mayflies, ignoring the much larger skwallas and gray drakes that are on the water at the same time.
The next important spring hatch, gray drakes, usually begins in earnest about the last week in March, but might not show steadily until mid-April. Many anglers call the mayfly a March brown.
“Technically, the March brown is an Eastern fly hatch,” he said. “We call ‘em gray drakes. But people around here know which insect it is when you call it a March brown.”
Whatever you call it, the gray drake is a large, juicy mayfly that definitely gets a trout’s attention.
“You can generally get away with up to a size 12 fly on the Clark Fork,” Gould said. “The ones that get started on the Bitterroot are a little smaller.
“On the Bitterroot, we use a size 14 as a rule, up to a 12. The fly we use most is an extended-body drake. So, on a standard size 14 hook, you could call it a size 12 fly. The body is typically a light gray color in a parachute pattern. Or a size 12 Adams works just as well on most days.”
Rock Creek has a great gray drake hatch, he added.
“A lot of times,” he said, “you’ll see gray drakes on the upper end before you see skwallas.”
Usually about the end of the first week in April, Gould said, the grannom, or “Mother’s Day” caddis hatch is added to the aquatic insect bouillabaisse. A heavy caddis hatch can trigger a trout feeding frenzy, he added.
“The hatch tends to be in the afternoon, from 3 o’clock on,” he said. “I like a small Goddard pattern, or an elk-hair caddis, or Gary LaFontaine’s emergent sparkle pupa.
“Size 16 is pretty much what to go with 90 percent of the time, up to a 14. It’s a gray-bodied, slate-winged critter. About the time the caddis hatch gets going good, suddenly the river is full of trees in the rush of high water, and it’s all over.”
Throughout March and April, there are two types of stoneflies other than skwallas that provide prolific hatches on western Montana streams. But, Gould said, the “tiny winter black” stonefly (size 16 to 18) and the larger “winter black” variety (size 14) seldom elicit active surface feeding by trout.
Midges, the miniature aquatic flies that hatch year-round, can still be important parts of the trout’s diet during the spring insect bonanza, said Gould.
“You will still find fish that are keying on midges,” he said. “And if you don’t mind putting on the smaller stuff, there are times when it makes the difference.”
Of all the spring hatches, however, Gould has a favorite.
“You can’t help but love skwallas,” he said. “There’s no way around it. It’s hopper fishin’ in March and April. You can slap ‘em down. You can skitter ‘em. And fish just explode on ‘em.
“You rarely see skwallas flying,” he said. “It has to get to be close to 70 degrees and sunny to see ‘em in the air. They just don’t like to fly. But that doesn’t mean they aren’t hatching and fish aren’t aware of them.”