Grousewing sedge

Trout & Salmon (UK) - - First Cast - By Craig Ma­cadam, co­or­di­na­tor of the River­fly Record­ing Scheme.

Of all the adult cad­dis­flies the Grousewing sedge (Mystacides longi­cor­nis) is per­haps the eas­i­est to iden­tify. These small in­sects have long slen­der yel­low­ish-brown wings, punc­tu­ated by three darker bands which, as its com­mon name sug­gests, re­sem­bles a grouse feather. This cad­dis­fly is found in all types of still­wa­ters, in­clud­ing lakes and ponds, as well as canals and slowflow­ing rivers. The lar­vae have par­tic­u­larly long hind legs, which they use for crawl­ing in mud and sand on the bed or climb­ing among sub­merged veg­e­ta­tion. The Grousewing is one of the brown sil­ver­horn sedges, so called be­cause of their long white an­ten­nae, which ex­tend to two and three times the length of their body. They also have dis­tinc­tive large red eyes, which make them un­mis­tak­able as they rest on bank­side veg­e­ta­tion. Grousewing lar­vae cre­ate a long slen­der, slightly curved case from sand grains, oc­ca­sion­ally in­ter­spersed with bits of veg­e­ta­tion. Most cad­dis make a new case at each of their five moults but in­stead, the Grousewing merely adds an ex­ten­sion to its ex­ist­ing case. This re­sults in the case ta­per­ing to­wards the rear. The adults emerge from the wa­ter sur­face dur­ing late af­ter­noon and early evening, some­times in huge num­bers. These dense hatches can be spec­tac­u­lar with the air filled with danc­ing sedges. Dur­ing the day they avoid the heat of the sun by rest­ing in bank­side veg­e­ta­tion, wait­ing un­til cooler con­di­tions to restart their mat­ing swarms. The males sweep back and forth over the sur­face of the wa­ter and the fe­male en­ters the swarm where she is grabbed by a male and mat­ing fol­lows. Once mated the fe­male

Long white an­ten­nae and banded wings.

will re­turn to lay her eggs by dip­ping the end of her body in the wa­ter while skim­ming low across the sur­face.

Did you know?

The Grousewing is found through­out the coun­try from Orkney to Corn­wall.

Body: 6-9mm. Wing: 7-10mm. Flight pe­riod: June to Septem­ber. Hatches: late af­ter­noon and evening.

Newspapers in English

Newspapers from UK

© PressReader. All rights reserved.