Callibaetis Mayflies

If you are going to be fishing stillwaters, the number one mayfly that you need to be familiar with is the Callibaetis. They are the most important stillwater mayfly of all. There are some respected anglers here in Northern California that believe that there is no insect more important to the stillwater angler.

The damselflies provide exciting angling for large trout, and on many lakes midges are of major importance, but as a searching pattern you can't go wrong tying on a Callibaetis nymph.

Callibaetis are found in many types of stillwaters and especially in the waters where we search for trout. If you are fishing a lake that has a good supply of weeds, you will have probably find lots of Callibaetis.

The Callibaetis nymph is a stillwater bug that is available 365 days of the year and it predictably hatches throughout the entire fishing season. If you had to design a stillwater bug for stillwaters for fly fishers, the Callibaetis would be it. It acts predictably and trout key in on that predictability. All stillwater anglers should take time to understand the life cycle of the Callibaetis will benefit from the time spent with trout at the end of the line.

The Life Cycle of a Callibaetis Mayfly

The Callibaetis belongs to the Baetidae family of mayflies. The Baetidae family of mayflies are multi brooded. The nymphs mature exceedingly fast and several generations will emerge within a single season. Most other mayflies hatch only once in a brief annual flurry.
The Callibaetis is a prime example of a mayfly nymph with a perfectly proportioned body. The head is slightly narrower than its shoulders and the slender body tapers to three equal length tails that are about as long as the body. It has heart shaped gills that fringe each flank of the abdomen. The sweeping antennae twice as long as the head is wide. The only other stillwater nymph that might be confused with the Callibaetis is the Siphlonurus whose antennae are short and stubby by comparison.

The Callibaetis nymph is a chameleon. The nymphs can change color quickly to match their environment. Tie colors of this nymph to match the colors of the vegetation of their stillwater environment. You can tie the nymph in earth tone hues like natural or olive hares ear or use pheasant tail.

The nymphs have a semi-rigid exoskeleton that must be periodically molted. The typical Callibaetis might undergo a twenty or more such molts throughout the winter.

Early in spring the callibaetis began their hatching process. Gasses in their exoskeleton begin to fill their bodies. As this pressure builds, the exoskeleton starts to swell and the nymph becomes buoyant. As the exoskeleton stretches it radiates a shimmering glow. When this happens the nymphs starts crawling upwards. This can be a mass emergence with the nymphs crawling up the reeds, and other underwater structure towards the surface.

Often when these emerging nymphs lose their footing or try to swim, the buoyancy lifts them away from their structure and they desperately swim back down to the protective cover. This can happen over and over. This is prime feeding time for the trout. This happens every morning and all season all season long. The trout of stillwaters get accustomed to this daily rhythm. For the stillwater angler this is prime time.

How to Fish the Nymph Stage of the Hatch

It pays to get out on the water around nine am. You can use a floating or intermediate line. I prefer using a Cortland Camo Intermediate line. Rig up with a standard nine foot tapered and extend it with fluorocarbon tippet to 1 1/2 time the depth of water you intend to fish. We're talking the tippet section here, So in 6 feet of water that's 9 feet of tippet. That makes your total leader length 18 feet. In water that doesn't have good clarity you can cut that back to 12 or 14 feet total. You can start with 5x and if the fish aren't cooperating go smaller with 6x.. You then need to determine the depth and clarity of the water.

Tie on your callibaetis nymph imitation of choice of the appropriate size. Work your line out as best as you can with the extra long leader. It's OK if the tippet doesn't straighten out. Count down the nymph until you see it hit the weeds. You'll know it has got there when the vee shaped wake from the sinking leader stops. Mentally record the seconds it took to get the nymph to the weeds. Re-cast and count it down again. Try a very one very slow, very long strip until the stripping arm and hand are extended behind you. Trap the line against the cork with rod hand and let the nymph fall. Watch the vee of the tippet for the take. The long slow strip does a good job imitating the nymph being buoyed to the surface and the subsequent fall of your pheasant tail mimics the real nymph’s frantic return to cover.

Watch the tippet as it is your best indication of a take. You may not feel the take. Tighten up with any un-natural movement. A stop, a change of direction, a dimple. Using tippet as small as 6X tippet might seem too small but with a long leader it has tremendous stretch and will handle most trout, even hogs. Just make sure its fluorocarbon. The small diameter tippet allows your nymph to cut through the water.

Fishing the Emerger and Dun Stage of the Hatch

The Callibaetis nymphs start to hatch as the morning progresses. They hold just beneath the film with only the hump of the thorax breaking the surface film. Soon the thorax splits and the adult emerges. Its head and then its legs crawl out out of the exoskeleton. It will spread its legs out across the water and then draws the wings and abdomen out of the shuck. Once this is accomplished only the tail remains in the husk and then it finally pulls free . The dun then drifts across the waters surface as the wings harden.

The coloration of the Callibaetis changes as the season progress. In the spring the insect is dark sooty gray and as the hatches progress through the season, they get increasingly lighter hues. In the fall, as temperatures drop, the mayflies once again emerge in the darker colors. This is said to be natures way of absorbing more heat from the sun. The underneath side of a Callibaetis are always lighter than the top. The wings of the Callibaetis duns will have distinctively light colored veins that contrast with the relatively dark wings giving them a speckled effect. Their common name is the speckled dun.

When fishing and choosing which stage of the Callibaetis to match it is good to remember that as the nymphs drift up from the weeds and converge on the surface, the trout sometimes get selective to the emerger and cripples. Fish will often disregard the nymphs and duns and focus on the emergers. The emergers are hapless prey and the fish can take their time picking them off. They can't swim or fly.

Two "Go To" paterns to imitae the Callibaetis emergers are a Quigley's Cripple and a Bivisible Dun. You do not have to match the size of the emerging dun when fishing emerger patterns. A size twelve nymph can be fished with size 10 emerger. The trout aren't as selective at this stage.

Callibaetis Spinners

The Callibaetis duns will leave the water and fly to stream side vegetation. They will molt into sexually mature spinners. The spinner has translucent wings with only a trace of splotching on the leading edge. About mid morning the next day, or sometimes in the evening, droves of males rise from the stream side vegetation and form clouds of insects that fly high into the air and flutter back towards earth.

As they are rising and falling above the stream side vegetation the fall males are releasing pheromones that waft downwind and attract the females. The females flutter into the bobbing mass of males. The insects briefly copulate in flight and the males go off to die.

Just about the time the morning hatch is winding to a close, the spinners arrive to lay their eggs. The female Callibaetis whisk along the surface of the water and dap their abdomens into the film to release showers of fertile eggs. The eggs hatch almost immediately and the cycle begins anew.

For fly fishers, as soon as spinners start landing on your arm or the trout begin to refuse your emerger or cripple imitation, tie on a spinner imitation.


To imitate a Callibaetis spinner the best spinner patterns are barely there. Try a pattern like a CDC Biot Spinner. The CDC biot spinner works well because it uses sparkle organza and the fluted CDC feathers trap air like the real spinner wings.

Remember the "Multi-Brooded" aspect of the Callibaetis
Beacuse the Callibaetis is multi brooded. It emerges in the spring as a size twelve. About six weeks later, the progeny from the first hatch will emerge but they will be a size fourteen. Six weeks later the next brood will hatch and be a size sixteen and so on until the end of the season when Callibaetis in October are popping off in a minute size twenty.

Every six weeks or so will be a major emergence period, but enough bugs are out of sync that Callibaetis hatches can be counted on virtually every day of the season. The nymphs of the season’s last brood having all winter to grow, will emerge the following spring in a succulent size twelve to start the cycle once again.

Summary

So, you can almost never go wrong using a Rickards Callibaetis nymph as a searching pattern in any stillwater that you find anywhere. Tie nymphs in sizes from 14 to as small as size 20 in colors to match the vegetation in the lakes you are fishing. Good luck!