Hatch Profile – Damselflies

by | Jul 16, 2019 | 0 comments

While most of the insect species that fly anglers find relevant exist in relative obscurity outside of our odd band of brothers and sisters, the damselfly is well known to nearly anyone who has spent time near water.  Their adult forms are fairly large, with beautifully colored and patterned bodies, bulbous compound eyes, and flight skills that might make you believe that fairies do exist.  Montana is home to 36 species of damsels (scientific order Odonata / suborder Zygoptera), and with common names like River Jewelwing, Emma’s Dancer, Sedge Sprite, and Alkali Bluet, the intrigue only grows.  Their conspicuous presence on warm, calm, summer days at the lake make these insects a symbol of good times.

But hidden behind the feminine name of this insect is a nasty secret.  They are deadly predators.  That fact alone makes them obviously cooler than your average mayfly!  Damselfly nymphs are equipped with a long, extendable mouth part (think of a hinged arm with a pincer mouth on the end) which they are able to shoot forward at amazing speed to capture prey that includes tiny daphnia, other aquatic insect larvae, and even small fish!

Adult damsels are equally predatory, and we regularly observe them zooming about, feeding on emerging Callibaetis mayflies while we are out gulper fishing.  Damsels also feast on mosquitoes, which makes them a friend of mine.

While their predatory ways make them interesting, there are other facts about damselflies that are far more relevant to the angler.  Damsels have a relatively simple, 3-stage life history (egg, larva/nymph, and adult), lacking the pupal phase that stillwater anglers focus so heavily on with caddis and chironomids.  Damsels hatch in the late spring and early summer generally, but the timing is more dependent on water temperature and weather than a date on the calendar.  So, on higher elevation lakes such as Henry’s and Hebgen, damsel hatch conditions typically occur from late June through the month of July. Damsel nymphs hatch by swimming from their home among the submerged vegetation towards shore or emergent vegetation, boats, docks, etc, where they crawl out of the water, and their shuck splits open to revel the winded adult.  They do not emerge on the surface of the water like Callibeatis mayflies.  Adults spend time both near water and away from it feeding, and both females and males return to water to lay eggs on/in vegetation and guard egg laying females respectively.

As such, it is the nymphal phase rather than the adult phase of the damselfly which is most relevant to the stillwater angler (more on the adults later).  With the aforementioned 36 species of damselflies in Montana, imitation might seem like a daunting task, but fortunately, only a subset of them overlap with prime trout water, and then, basically all of those fall into the same description in terms of shape, size, and color.  Damsel nymphs have an unmistakable shape.  Their bulbous eyes and wide head carry over from nymph to adult and are a key feature of many imitations.  Their bodies are slender and wiggly, with feathery gills at the end of the abdomen.  Legs are sparse but prominent, extending to both sides of the thorax.  Nymphs vary in size over their lifetimes, but those which are nearing adulthood are most exposed to the trout, when they swim from their weedy homes towards shore to hatch, or when they are moving about and hunting.  These creatures are typically ¾ of an inch to 1 ½ inch long.  I hesitate to refer to a hook size, as the tail makes up the length of most damsel nymph patterns, but I tie mine on hooks ranging from 10 to 14 typically.  In my experience damsel nymphs vary in color depending on the  color of the substrate or vegetation they live in.  That means a lot of olive tones, with occasional instances of brighter, almost chartreuse green, subdued tans, and even dark browns.

Damselfly nymphs swim by undulating their body not-unlike a fish, with their 3 feathery gills functioning like a tail. Their movement patterns typically include slow wiggles, quick darts, and prolonged resting pauses.  On any given day, one or more of these may act as the trigger to hungry trout, so be prepared to vary your nymph retrieve with a mix of hand twists, rod tip twitches, short but quick pulls, and extended pauses. Damsel nymphs do not swim with an up and down motion like leeches, and do not sink quickly when resting, so weighted patterns may not be the ideal choice in some instances where pronounced pauses are included in your retrieve.  Damsel nymphs also swim towards things to crawl out on to hatch, so theoretically that means mostly towards shore.  But damsel nymphs also crawl onto a boat or float tube to emerge, so that is great news.  Interestingly, I have not found casting direction to make as much a difference as the presence of feeding fish.

The easiest way to recognize an active damsel hatch event is by observing the nymphs crawling onto shore, vegetation, or your boat to hatch in significant numbers.  Increased bird activity in the shallows is another sign.  So are violent swirling rises of fish feeding on nymphs just below the surface.  Massive damsel emergences can provoke epic feeding binges from every trout in a lake, including the giants.  They can also provoke epic frustration among anglers, maybe due to the sheer competition between your one fly and the thousands of naturals.  I have encountered some instances where the trout really want a realistic imitation.  This typically occurs in clearer water and calmer conditions.  In other cases, where there is a tint to the lake, a chop on the water, and a thick hatch, a more suggestive fly pattern seems to stand out and get chomped well.  Be ready with both options, and both floating and slow sinking intermediate lines to cover your depth range. Lastly, because damsel nymphs are a nice sized treat, they seem to work well as general searching patterns whenever damsels are active on a lake.  In other words, an actual hatch even is not required to catch fish on damsel nymph patterns.

So what about those adult damsels?  They are so beautiful, and are so busy on the lake in summer.  Fish must eat them, right?  They do, but in my experience not all that regularly.  They have a habit of hunkering down in the reeds or willows when the wind blows, and occasionally a big gust will knock a few into the water on the margins and creating a fleeting angling opportunity for those willing to brave the big winds.  Still, adult damsel dry flies are so fun to tie and so cool looking that I always have a few collecting dust in my box to imitate the usual blue, tan, and also the gaudy red adult species.  With all that said, two of the most memorable stillwater fishing experiences I know of involved adult damsels.

Once, long ago, on a small pond here in Montana, when I was really just beginning my stillwater angling life, I tied on a floating damsel adult.  I hucked it out in the middle of the pond and after about 30 seconds, an actual living adult damsel flew over and landed on my fly.  I started to think, “Oh, that’s pretty cool” when a giant trout came up and sucked both my fake and the real hitch hiker damsels down in a huge swirl.  Fish on!

The second experience was shared with me by a friend who lives in Oregon.  He actually experienced big rainbows selectively feeding on adult damsels that were perched on the reeds 2 to 5 inches ABOVE the water’s surface.  The bows were literally leaping out of the lake to eat them off the reeds.  One fish ate a floating adult pattern cast near the reeds, but the sight of those leapers, watching them ignore a fly on the water, and their selectivity for the natural insects that were not even on the water is what made the event so memorable (and frustrating).

Lastly,  damsels are primarily a stillwater insect, but they also inhabit slower moving and vegetated streams and rivers.  In our area, this is an overlooked fact, and perhaps something worth exploring more during periods of minimal hatch activity that coincide with favorable water conditions!