Diel periodicities of adult emergence of some chironomids (Diptera: Chironomidae) and a mayfly (Ephemeroptera: Caenidae) at a Western Australian wetland

Diel periodicities of adult emergence for three species of Chironomidae and one Caenidae from a Perth wetland were recorded during spring and summer. All chironomid species emerged mainly at dusk, regardless of sex, with the peak rate of emergence occurring during a 30 to 60 min interval beginning within 30 min of the time of light extinction. Light intensity appeared to be the major factor regulating the time of emergence. The emergence of the mayfly occurred at dawn during both spring and summer and may be controlled by an endogenous circadian rhythm