ORIENTATION OF IMAGINES OF CAPNIA ATRA MORTON (PLECOPTERA) .2.

1. Newly emerged imagines of Capnia atra Mort. migrate from both banks of the Stora Lule river (near Messaure Swedish Lapland - 66° 42′ N, 20° 25′E) at right angles to the edges of the woods which run parallel to the river. In the woods they keep their direction. They continue to migrate for about 50 m and then creep under the snow. 2. Insects from one side of the river, when put in the woods on the other side, keep to their original migrating direction, i.e. they migrate towards the river. They also keep to their direction, if they are transported to a nearby plane surrounded by woods. On being put on the flat bank they reorientate towards the nearby wood. The new migrating direction is thus turned by 180° compared with the original one. 3. In a tunnel where daylight is excluded, Capnia atra reacts slightly positive phototactic to a stationary artificial light. The same animals, when brought back to a riverbank, retain the former migration direction. 4. Exposed to continuous darkness for more than 48 hours the animals do not longer keep to their original migrating direction. They are now bound by landmarks and, when put into the tunnel, they react strongly positive phototactic. © 1969 Springer-Verlag.