Is any creature in BC as under-appreciated as the caddisfly?
Caddisflies are shape-shifters and master builders who exist in both water and air. They are hairy-winged cousins of moths and butterflies, and relatives of dragonflies. And in the rich panoply of BC watershed dwellers, they’re a very big deal.
Photo credit: Bob Hendricks via Flickr, Creative Commons
These creatures, however, get short shrift. Consider one dictionary definition in the Oxford English Dictionary: “a feeble-flying usually nocturnal insect of the order Trichoptera, living near water.” That’s curt–maybe even caddish (“ungentlemanly, blackguardly.”) Common descriptions refer to adults as “dull” and “drab,” in contrast to their glamorous butterfly and moth cousins. Few people observe the exquisitely beautiful larvae stages underwater.
We are going to make the case that these benthic invertebrates–also known as sedge flies, rail flies and sometimes river flies–are unsung watershed wonders.
We know: bugs are unlike BC’s charismatic bears or salmon. But please take a moment to consider the caddisfly. You may be hooked. Especially if you’re a rainbow trout.
Photo credit: budak via Flickr, Creative Commons
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Five Facts About The Caddisfly
- Caddisfly larvae are awesome indicators of water quality. They do not tolerate pollution, so if they’re absent from a waterway we know there’s cause for concern.
- Caddisflies are critical in BC’s food web. As larvae they are essential in aquatic energy and nutrient cycles, and provide food for fish including salmonids. In their turn they eat plankton, plant debris and other insects. The adults are food for birds, bats and other insect-eaters, and pollinate plants as they move about feeding on nectar.
- Caddisflies are master builders–the insect equivalent of star human architects. As larvae, most species spin sticky silk from a gland in their lower lips, which they use to craft protective tubes of twigs, stones, sand and sand. Caddisfly larvae armour is “a bejewelled coat of many colours,” said an appreciative blog in the World Wildlife Fund, adding that the silk-spinning adults build “an amazing array of ‘houses’.” Caddisfly names reflect their talents. BC’s 275 kinds of caddisfly, noted the Royal BC Museum, include 21 “Net-spinning Caddisflies,” 13 “Trumpet-net Caddisflies, 13 “Saddle-case Making Caddisflies” and 14 “Purse-case Making Caddisflies.”
- All caddisflies go through a complete metamorphosis in their life cycle, from eggs to larvae to pupa to adults that breed and lay more eggs. Caddisfly larvae resemble caterpillars with legs, are about 3 cm long, and live for months or years on the bottom of waterways before pupating. When ready to emerge from their pupa, they rise directly to the surface or crawl from the water onto rocks and sticks, wriggle free, and take wing. Adults have drab-coloured hairy wings, antennae as long as the rest of their body, and survive for weeks or months by eating nectar and drinking water.
- When ready to lay their eggs caddisfly females–depending on the species–dive or crawl down through water to lay clumps of eggs on the bottom, or deposit eggs while floating on the water surface or flying low and repeatedly dipping their abdomens into the water. Some species leave their eggs on vegetation, where rain will eventually wash them into the water.
While caddisflies may not be noticed by most British Columbians, they are highly valued in some communities.
Ecologists recognize the role they play in the environment.
Anglers treasure them, frequently as bait but most remarkably as models for fishing flies, some so beautifully crafted they are forms of art.
In the global fine art world, caddisflies have made their name as sculptors in their own right. French artist Hubert Duprat of France set larvae up in a tank with grains of gold and precious stones, resulting in exquisite decorative cases.
Image credit: Hubert Duprat, Creative Commons BY-SA 3.0
Robert Louis Stevenson may well have been thinking of the caddisfly when he wrote, “The world is so full of a number of things, I’m sure we should all be as happy as kings.”
Image credit: Jerry Schoen via Flickr
