greentail
/ˈɡriːnteɪl/noun
A caddis fly that carries its greenish egg-mass at the tip of the abdomen; specifically (in Europe) Brachycentrus subnubilus (family Sericostomatidae). Also: an artificial fly made in imitation of this. Also called grannom. Now rare.
Origin
Late 17th century; earliest use found in James Chetham (bap. 1640, d. 1692), writer on angling. From green + tail.