Periodic phenomena are common in organisms, from plants which show them by the diurnal or nocturnal attitudes of certain species, up to the human species and certain mammals, where they appear in the female sex in the form of menstruations.
Indeed, the phenomena of the life of articulates are explained, perhaps, by rhythms of shorter or longer duration. So it is with egg-laying, which comes about with many species at certain epochs ; without doubt, also, the faculty which the queens of wasps and bees have of producing male eggs at certain times,-that is to say, non-fecundated eggs. Eoubaud (1915) reports that a certain coccid cared for by the ants is carefully carried under the ground and remains there during the time when the fruitage of the plant is being harvested. This is consequently a seasonal practice, and it will be interesting to know if it has left a trace in the behavior of the two kinds of insects.