WING POLYMORPHISM IN CAPNIA-BIFRONS (PLECOPTERA, CAPNIIDAE)

In the stonefly Capnia bifrons, a first description of relatively long winged, brachypterous instead of micropterous, males is given. Two ne ighbouring populations, one with brachypterous, the other with normal micropterous males, are compared. It appears that the brachypterous ma les pass through one more larval instar than the micropterous ones. Ma le brachypterism of Capnia bifrons in the present population probably results from genetic determination, rather than from modifying environ mental factors.