Periodical Insects

Abstract

In periodical insects the life cycle has a fixed length of k yr and the adults only appear every kth yr. Mathematical models were constructed to investigate the roles of competition between larvae of different ages, predator satiation, and parasitism in leading to periodical behavior. Periodical behavior resulted if competition was more severe between than within year-classes, predator satiation did not lead to periodical behavior in itself but had a powerful effect in reinforcing the tendency of competition between year-classes to lead to periodical behavior, and parasitism usually lead to an alternating oscillation in which every other year-class was present. Predator satiation was likely to be the most important factor in leading to the synchronization of the year-classes in congeneric species of periodical insects. The life histories of 3 periodical insects (periodical cicadas, May beetles, and the northern oak eggar moth) are briefly described and interpreted in the light of the theoretical results.