SEASONAL LIFE CYCLE IN TWO SPECIES OF ANT-LION (NEUROPTERA : MYRMELEONTIDAE)

Abstract

The seasonal progression of larval development in two sepcies of ant-lion was studied near Hirosaki. Hagenomyia micans was observed to pass the first winter in either the first or second instar and the second winter in the third (last) instar. Some larvac might take three years to mature, hibernating twice in the third instar. Myrmeleon formicarius hibernates at any instar usually for only once in the larval life and exceptionally passes the second winter in the last instar. Both species can thus tolerate winter dormancy at any larval stage. This characteristic seems to have evolved in connection with the pitfall method of hunting, for the food supply and therefore the larval growth should necessarily be inter-mittent and unpredictable. The longer generation time in H.micans may be an adaptation to the scarcity of food relative to its large size. In spite of the variable seasonal progression of larval development, the reproductive activity in both species occurred over a restricted period in summer, suggesting the existence of some mechanism to synchronize the adult eclosion.