Malham Sedge Caddisfly
Agrypnetes crassicornis
About
Agrypnetes crassicornis (The Malham Sedge) is a flightless caddisfly which skates over the surface of the water. 10-17mm in size with pale brown wings with prominent wing veins.
They lay a jelly ring of eggs on the underside of stones close to the shore of the tarn. When these hatch the larva move into the stonewort beds in the centre of the tarn.
Stonewort is a plant which deposits lime on the outside of its leaves.
The caddisfly lava makes a case from stonewort pieces and eats midges and other small insects. When it has finished feeding, it goes to the bottom of the plant and seals up its lava case and turns into a pupae.
The Caddis pupa is very thin and flexible so it can make the shears on its head work to cut open the case. When it is ready to turn into an adult caddis, it leaves its case and swims to the surface where it quickly splits its pupae and emerges as an adult caddis. It then quickly skates across the surface of the water to the shore where it then stays.
Only found in Malham Tarn in the UK. This location is a very unique habitat, the highest lake in England and one of only 8 upland alkaline lakes in Europe.
Conservation status
Critically Endangered and Nationally Rare
Malham Sedge
Dancers on the tarn’s skin, they skate for land,
giddy and electric, a panic of skittering legs,
fish mouths gaping hungry beneath them.
They are a spell, rare and elusive, flightless
wings stitched to the darkness of this marl lake,
the secret crackle of stonewort in its depths.
The larvae split their cases, instar
on instar before rising to this final rush,
feet tapping water as they hurtle towards shore.
One female makes it to a rock, waits damp
glistening in the shadows, more aquatic than air,
whiskery antennae twirling like exposed nerves
wings pressed doilies of darkling lace,
skeletal seeds: she’s lattice brown wet,
flinching from light, black eyes gleaming.
Later, the wash will carry her jelly loop of eggs
back to the heart of the lake, a return to the song
of stonewort, a return to the call of the deep.
Length: 80 seconds
Poem: Rachel Bower
Read by: Rachel Bower
Sculpture
The sculpture was very much inspired by Rachel's poem, the movement of the caddisfly from above to below the surface of the tarn led to the creation of the bronze line between these two worlds. This was combined with the poem which was laser-cut from wood and added to the background.
Malham Sedge
150x50x8cm
Bronze. wood, acrylic, exhibition panel, fabric
Work in progress
Images and videos of various stages of the sculpture's production:
We are very grateful to Sharon and Peter Flint for spending a day with us both, imparting lots of their knowledge about about this amazing insect. My drawing was also done from a photograph by Sharon Flint.