By: Rick Hafele
Lakes can save the day in the early spring when rivers are high and muddy, and the Callibaetis mayflies will often be your ticket to success.
There aren’t a lot of insect hatches that I plan my fishing vacations around, but for exciting fishing on stillwaters it’s worth planning a trip when the Callibaetis hatches are in full swing. The genus Callibaetis, commonly known by fly fishers as the speckle-wing quill or speckled dun, belongs to the family Baetidae. This is an important family as it also includes the widely distributed and very important genus Baetis, or blue-wing olive mayflies, found in streams. Blue-wing olives are consistently one of the most important hatches in streams for fly fishers to imitate. Callibaetis produce the same kind of abundant and consistent hatches, and are one of the most important hatches you will need to match when fishing stillwaters, and even some slow moving streams.
Because of their importance speckle-wing quills have been well documented in fly-fishing literature, often to the point of discussing specific species. Ernest Schwiebert in his classic book Nymphs, for example, provides a detailed account for seven species. The problem is that taxonomists have been revaluating the species of Callibaetis for sometime, so where there were once 25 described species in North America, today only 13 species are recognized. This means a number of species previously mentioned in fly-fishing literature are no longer considered valid. The species of greatest importance to anglers today include:
Callibaetis fluctuans – This species has remained unchanged. It is found across North America from the Northeast to the Northwest as well as into Southwestern states. It is one of the more important species in eastern states.
Callibaetis ferrugineus – This species has been divided into two sub-species: C. ferrugineus ferrugineus, and C. ferrugineus hageni. C. f. ferrugineus occurs throughout northeastern states, while C. f. hageni lives across the west. In addition, several previously well-known western species (C. americanus, C. coloradensis, C. hageni, and C. nigritus) are now all considered synonymous with C. ferrugineus hageni. As a result C. ferrugineus hageni is the most common and important species found throughout the west, occurring in high mountain lakes to low elevation lakes and slow moving streams from the Pacific Northwest through the Rockies.
Callibaetis pictus – This species was previously called C. pacificus, and primarily occurs from the southwest through the Rockies and into the Pacific Northwest, though some scattered populations of this species also occur in the Northeast.
Callibaetis pallidus – This species has remained unchanged and is primarily found in high elevation lakes throughout the Rockies with some populations also occurring in the Northwest.
While knowing how species names have changed or which species is hatching may impress folks around the campfire, it’s of little importance when it comes to matching the naturals and catching trout. What is important is that Callibaetis occur across the continent, and will often be the most important mayfly hatch in stillwaters. In general populations tend to be more widespread and abundant in the west than in the east or Midwest, though populations can be locally abundant throughout their range.
Recognizing Callibaetis is relatively easy. First, only a few mayflies live in stillwaters, with each quite distinct in size and shape. Callibaetis nymphs are slender and streamlined in shape. They have three well-developed tails of equal length, and antennae two or three times longer than the width of their head. Their gills, located on the sides of the first seven abdominal segments, have recurved flaps that increase their surface area and help them get enough oxygen out of slow moving or still water. Body color ranges from light gray to brown, as well as shades of olive. In general nymphs tend to be the color of the substrate they are living on. Callibaetis nymphs are most easily confused with Siphlonurus, or black drake nymphs. To tell them apart look at the antennae; Siphlonurus have short antennae, no longer than the width of their head.
Duns and spinners have two tails, about body length in duns and twice the body length in spinners. Wings are mostly brown or gray in duns, with distinct light markings along the wing veins. Male spinners usually have clear wings, while female spinners typically have wings marked with small dark splotches along their leading edge. The common name, speckle-wing quill, stems from these markings. The size of mature nymphs, duns, and spinners varies with species and time of year. Body length, excluding tails, may range from barely a quarter inch to about a half-inch long.
Several characteristics make Callibaetis particularly important to fly fishers. I’ve already discussed their wide distribution and frequent abundance. Another major factor is that just like the blue-winged olives, speckle-wing quills have two or three generations a year, meaning you will see more than one hatch of adults during the season. The first, and often heaviest hatch will be in the spring, anywhere from March through June. The timing is triggered by water temperature with emergence activity starting when it rises to around 45 degrees. Thus, lakes in warmer latitudes and lower elevations that warm up early in the spring will see hatches begin in March or April. If you go further north or further up in elevation, hatches may not begin until May or June, or even July. This also means that you can greatly extend the spring season of Callibaetis
hatches by traveling to lakes at different locations or elevations. This is particularly easy in the west where lakes with good Callibaetis populations range from near sea level to over seven or eight thousand feet high. In many lakes a second hatch will occur in July or August and third in September and October. Lakes that warm up late will generally only see a late spring/early summer hatch followed by a brief fall hatch. The size of mature nymphs, duns, and spinners will be largest in the spring and smallest in the fall.
Another reason speckle-wing quills are so important is their behavior. Mayfly nymphs are generally lumped into one of four groups based on behavior: burrowers, clingers, crawlers, or swimmers. Callibaetis
nymphs are excellent swimmers. They have three tails fringed with interlocking hairs that create a paddle-like surface, and with a few quick flips of their abdomen nymphs dart through the water almost as fast as little minnows. While Callibaetis nymphs prefer to stay hidden among lake-bottom vegetation and debris, they do swim when disturbed and can be readily available to feeding trout.
Mature nymphs become even more important. When ready to emerge into duns the nymphs begin a restless swimming action up from the lake bottom towards the surface, rising several feet then dropping back down. After a few minutes of this tentative behavior they finally decide the time is right and swim all the way to the surface. Once at the surface the nymph’s exoskeleton splits and the dun quickly pops out onto the water’s surface. On cold days duns may sit on the water 30 seconds or more before taking flight, but on warm days they will get airborne within a few seconds. This emergence behavior means trout have ample opportunity to feed on swimming nymphs, both below the surface and in the surface film, as well as newly emerged duns on the surface.
The duns lucky enough to avoid a trout’s mouth head for streamside foliage to rest. Eight to ten hours later the duns (also known as subimagoes) molt one final time into the reproductively mature imago stage, better known to fly fishers as the spinner. Anytime from mid-morning to late afternoon, male spinners form large swarms ten feet to forty or fifty feet above the water. Female spinners fly into these swarms where the males race to reach the females first. Mating occurs in the air, shortly after which the males die. Nearly all female mayflies begin laying eggs immediately after mating, but Callibaetis females depart from this typical behavior. Instead, they return to nearby trees and shrubs where they wait for their eggs to ripen, a process that may take four to seven days. With ripened eggs ready, the females fly back over the water, usually in the mid to late afternoon, drop to the water’s surface, and release their eggs. Since the eggs have already matured within the females, they hatch into the next generation of swimming nymphs almost immediately on contact with the water. The spent females then die on the surface creating another excellent feeding opportunity for fish.
To imitate Callibaetis effectively you’ll need to be prepared with nymph patterns, surface emergers, and dry flies for the duns and spinners. Let’s start with the nymphs. A wide variety of nymph patterns have been created for Callibaetis. In my opinion keep nymph patterns simple, sparse, and slender. These are swimmer nymphs, so their body shape is long and slender. It’s a good idea to match that silhouette with your pattern. You should also pay close attention to the size of the naturals where and when you are fishing. Nymphs of different species will mature at different sizes. Plus, mature nymphs progressively get smaller through the season. This means you might need a size 12 in April, a 14 in July, and a 16 or even an 18 in October to match the naturals correctly. Size is important so don’t ignore it. Color also varies, but is generally less important. Nymphs may be shades of gray, tan, brown, or olive. Use a pattern that’s close, but I don’t agonize over it.
If you are fishing before the duns have started to emerge, fish nymph patterns close to the bottom. I like to use a floating line with a leader at least as long as the depth of the water I’m fishing. Callibaetis
nymphs don’t live in deep water, preferring areas one to maybe ten feet deep with aquatic plants or wood debris, so a leader of ten to twelve feet will usually be long enough. Cast along edges of aquatic plants or where the bottom changes depth, then wait until your nymph sinks nearly to the bottom. Retrieve with three or four short strips followed by a pause. Experiment with the speed of your strips. It’s easy to strip too fast, but these nymphs swim well so make your nymphs look alive. Keep retrieving your nymph up towards the surface like a nervous natural that hasn’t decided if it’s time to emerge or not. Strikes can be quite strong or very soft, so lift up your rod when you feel any hesitation. Don’t strike hard or you will break off that big trout.
Once you see duns on the surface and fish showing interest, it’s time to adjust your approach. While it may appear that fish are taking duns and a dry fly would be the thing to use, often trout are taking nymphs hanging in or just below the surface film, or duns struggling to escape their nymphal shuck. If your dun imitation isn’t working put on a surface emerger pattern, or try fishing a nymph near the surface by tying it on to a 15 to 18 inch dropper off of your dry fly. Low riding surface emergers often prove to be the best answer for picky trout feeding at the surface.
The same presentation will work for emerger and dun patterns. Watch how the trout are feeding. Are they staying in one place or cruising over a wide area? Are they in pods or feeding alone? Once you know how trout are feeding, you’ll know if you should cast within a foot or two of their rises or ten to fifteen feet away. You’ll also know which direction the fish are moving so you can put your fly in their path. Don’t make a lot of casts. If fish are nearby it’s often better to let your fly just sit still on the water for several minutes rather than constantly picking it up and presenting it again five or six feet away. Making a lot of casts will almost always put fish down no matter how gently you present your fly
The last thing you are likely to see during a day with good Callibaetis activity is the spinner fall. It’s possible for the spinner fall to occur in the late morning, and yet you will see swarms of spinners in the air in the mid afternoon. Remember the egg-laying females you see on the water are ones that swarmed and mated several days earlier, so the timing of the spinner fall isn’t tied to the mating swarms you see like they are for other mayfly species.
If the spinner fall is heavy you shouldn’t have any problem seeing them on the surface. The rises to spinners will be much softer and less showy, than rises to the dun, so watch carefully for signs of feeding trout. Your presentation approach with spinner patterns will be the same as for duns or emergers. Watch where trout are feeding and how they are moving, then place you fly in their path. Once again it can be better to leave your fly still on the water for a minute or so, rather than making a lot of quick casts trying to cover a rise. The natural spinners are dead on the surface and thus not moving. Keeping your fly still on the water will better match this lack of activity.
The speckle-wing quills are widespread, abundant, and behave in a way that gives trout plenty of chances to eat them. As often occurs with insect hatches, you will generally find better Callibaetis hatch activity and surface feeding by trout on overcast days – or even wet rainy days - compared to bright sunny ones. Also remember to that the size of mature nymphs, duns, and spinners decrease with each successive hatch through the season, so adjust your pattern’s size accordingly. Callibaetis
produce some great lake fishing and are well worth planning a fishing trip around, especially when spring weather turns streams high and muddy.