The science and beauty of caddisfly larvae
Terence from the Ribble Valley has sent in a picture he took while out for a walk; it’s of some interesting-looking objects attached to the underside of a rock in a brook. Do you know what they are?
They’re the protective underwater casings of caddisfly larvae. The larvae use silk excreted from glands near their mouths like glue to bind gravel, sand and other small debris that they find into hard protective tubes. They seal the ends to prevent predators from being able to catch and eat them. There’s still gaps for water to flow through so the larvae can eat and grow without ever having to leave their shelter.
Once they have matured into adults they leave their protective home, leaving behind the hollow tubes seen in the picture, and make their way to the surface of the water to take flight. Adult caddisfly only live for about one to two weeks but it is possible for them to live for up to two months. After mating the female flies lay eggs just below the water’s surface ready to hatch into larvae, a process that takes about three weeks, and the cycle begins again!
French artist Hubert Duprat used caddisfly larvae to make art. He put the larvae in a tank where the only “gravel” they could use was gold and precious jewels, the caddisflies did the rest.
Here’s an interview with the artist:
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