REDSTONE • REVIEW
MAY 15 / JUNE 19, 2019
LOCAL A case for caddisflies By Greg Lowell Redstone Review LYONS – When my kids were young, we used to peer down through the clear window panes of ice on a slowmoving stream to watch the parade of caddisfly larvae on the muddy stream bottom. While above we shivered in the winter cold, these insects trudged along the streambed snug in their homemade tubes of sticks, pine needles and grains of sand. Here in Colorado, my introduction to western caddisflies came in the St. Vrain River. where – before the 2013 flood – the cobble rocks on the river bottom looked like little porcupines with stubby quills – the quills being the caddisfly larvae’s cases attached to the rocks. Today, the St. Vrain’s caddisflies have made a comeback, and are among the almost 200 species of caddisflies in Colorado. Caddisfly larvae comprise a large percentage of the macroinvertebrates found in the state’s waterways, from muddy streams along the Front Range to high, clear mountain streams above tree line. (Macroinvertebrates are aquatic organisms like crustaceans, mollusks or aquatic insects.) In discussing caddisflies, it’s tough to generalize about their life cycles and behaviors. There are almost a thousand distinct species of caddisflies in North America and while there are similarities, there are also many differences. Nature’s tiny homes What can be generalized about caddisflies is that their larvae are all aquatic and omnivorous, meaning they will eat mostly anything from plant material to their fellow underwater neighbors. The predominant caddisfly larvae here on the St. Vrain anchor their tube-like cases to underwater rock surfaces with their rear legs, poke their heads out of the opposite end and pick off food as it drifts by in the current. A few more-active members of the caddisfly family survive by spinning silk nets to capture prey or stalk their prey among the river bottom rocks. But in all three types, the larvae create a case in which to transition to the pupal stage. When removed from their case, the larvae resemble small caterpillars and, depending on their particular subspecies, are green. Fly fishermen key on this color when fishing underwater nymph patterns tied to resemble larvae poking out of their cases or free-roaming larvae. Caddisfly larvae emerge from the egg after 2 to 4 weeks and spin silk to bind together the materials of their tubu-
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party at the Lyons Senior Center by Loving Lyons Seniors. Lori will be leaving her position, after four years, at some time in May. Kathleen Spring took Lori and the seniors down Memory Lane by describing the many activities that Lori provided for the seniors over the years. The most popular ones are expected to remain for the rest
lar aquatic homes. The tubes can be made of grains of sand, small sticks, vegetation, bits of leaves and even discarded snail shells, depending on the water body. If caddisfly larvae live in a gravel-bottomed stream their cases are likely to be glued-together sand particles. If they populate in a slow-moving, debris-filled stream, their cases will be made of twigs and pine needles. The cases serve as both camouflage to allow them to prey undetected on other aquatic insects and for protection from their own predators. Many caddisfly larvae live their entire life – about one year – in the tube cases breathing through abdominal gills as water circulates through the tube.
Top: Caddisfly larvae rests on underwater grass. Bottom: Adult caddisfly rests on stream side vegetation. When it’s time to leave home The last order of larval business is to pupate. This process can take from several days to several weeks, depending on the caddisfly species. The caddisflies metamorphosize within their tube cases, then leave the case to rise to the surface. It is during this time that the caddisfly is most vulnerable to trout for which the caddisfly is one of its chief food sources. Fly fishermen know this
of 2019 which include a twice-weekly exercise program, monthly watercolor painting class, and quarterly bus trips to cultural events. The recreation assistant also organizes activities for the child, youth and adult sectors of Lyons.
Lyons Habitat buildings need volunteers
LYONS – Thanks to all the volunteers – both from Lyons and communities across the region – who helped to build the Habitat for Humanity housing on weekends and weekdays starting in January 2018. Later this spring and summer the other two duplexes are expected to be finished, but your help is needed. To volunteer, no specific experience is
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well and carry an assortment of both caddisfly nymphs and dry flies that replicate free-roaming larvae, the transitional pupae or adults. Some pupal caddisflies rise to the surface, struggle to break the water’s surface film and quickly fly away. Slower species will drift on the water for long distances while they shed their pupal shucks. Still others will crawl out of the water onto rocks, sticks and vegetation to dry out and take wing. Yet another species will make a beeline for the shore where they crawl out to complete the transition to adults. Looks like, but not, a moth The fluttering flight of the adult caddisfly resembles that of a moth. But, unlike a moth, the caddisfly adult has long forward-pointing antennae and has no coiled sucking tube for feeding. In fact, adult caddisflies don’t feed, and exist only to make more caddisflies. The adults are largely drab-colored. Here, along the St. Vrain River, many of the caddisfly adults are tan or darkcolored. Mostly nocturnal, the adults hide in vegetation during the day and are hard to find unless disturbed. Mating takes place at dusk, either in flight or on vegetation. Following mating, the females deposit egg masses either into the water or on aquatic vegetation. Compared to the ephemeral life of mayflies, caddisflies live a relatively long time. Although they do not feed, their mouth parts allow them to drink and avoid dehydration. Again, depending on the species, caddisfly adults can live from a few days to a few months. Mating continues so long as the adults are alive. Some adult female caddisflies deposit their eggs by flying low over the water and dipping their abdomen to release clusters of eggs that then drift to the bottom of the river. Females of other caddisfly species submerge themselves to lay their eggs on the stream bottom, either by diving down into the water or crawling down vegetation, sticks or rocks. Others flutter on the surface where they are easy targets for trout, while others ride quietly on the surface as they lay their eggs. Some egg-laying methods keep the adult females safe from predation. They may drop their eggs into the water from overhanging plants, or lay their eggs on streamside vegetation so the eggs will wash into the river during the next rain. Fly fishermen know caddisflies well. For the rest of you, the next time you’re down by the river take a moment to pick up a submerged rock and inspect it. Chances are you’ll see a collection of caddisfly cases and a few of their inhabitants waiting for the day they’ll take wing.
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needed, and training is on the job for each 9 a.m. to 4:30 p.m. volunteer shift. On the website at www.stvrainhabitat.org/construction, after clicking FLOOD REBUILD-LYONS, volunteers can review all volunteer days with openings and sign up for one or more of the specific days they are available. To donate online, go to www.coloradogives.org/rebuildlyons. For any questions, contact Rebecca Continue Briefs on Page 7
Acupuncture & Herbal Medicine Private Sessions or Community Clinic (lower cost) Available Carol Conigliaro Licensed Acupuncturist 303-819-2713 • At the Little Yellow House • 503 2nd Ave, Lyons
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Darrell F. Paswaters PO Box 2509 Phone (303) 823-3030 Lyons, Colorado 80540 Fax (303) 823-8718 email@example.com • www.aceheatingandcooling.com