Nation diary: the caddisfly larvae are rising, creatively camouflaged | Bugs


T.The vegetation at the bottom of my pond stirred and three small lumps sprouted from my legs and began to creep up the side. About an inch long, one resembled a branch of gorse with short leaves, while the second was a similarly compact collection of stems covered with a water snail shell as if added for decoration.

The third one, slowly approaching me over the algae, with a piece of catkins as a front bumper, was a more disorganized mess of bits of bark and plants, some pink like rhubarb stalks. Occasionally, as they reached forward, the inhabitants of these cumbersome structures showed themselves to be pale with long forelegs and a head banded with maroon – the mysterious larvae of Caddisflies.

Using sticky silk, these soft-bodied freshwater dwellers tie material together in ponds and streams to build their camouflaged mobile homes where they eventually pupate before hatching as flying adults. And the different designs can help identify the species out of the many dozen species that inhabit our waterways.

Some assemble a slender tube with a longitudinal cut that is laid lengthways, others a neat layer of pebbles made of gravel. And they were even encouraged in aquariums to design their temporary protective covers with gemstones to create unique and intricate pieces of jewelry. The jenga-style arrangements visible in my pond seemed largely the same as the descriptions for the common cinnamon sedge or limnephilus group of caddisflies.

Entomologists aren’t the only experts on the life cycle and appearance of these fascinating insects. Trout anglers tie artificial flies to mimic the immature stages as well as the moth-like adults, with their forward-facing antennae and wings tentatively held over their backs at rest.

Feeding trout easily cores caddisfly larvae, chopping them up like hard candy with soft centers, and removing adults from the surface when they hatch in large numbers in the warmer months. When I saw my surreal trio trample along the pond, I had to admire their ingenuity – even if they all looked like they had crawled backwards through a hedge.

Country Diary is on Twitter at @gdncountrydiary