ECLOSION AND OVIPOSITION RHYTHMS IN SIMULIUM ORNATIPES (DIPTERA: SIMULIIDAE)

In nature, adult Simulium ornatipes Skuse normally eclosed throughout the daylight period, but when water temperatures were high (≥26°), they eclosed mainly in the morning. Females usually eclosed slightly earlier than males. In the laboratory, daytime eclosion occurred under natural light and constant darkness but under constant white, purple‐pink and long ultraviolet light eclosion was arhythmic: these features are typical of circadian rhythms. Females oviposited throughout dark, cloudy days but on sunny, windless days they began ovipositing either when the sun decreased to a solar altitude of about 40 or when clouds covered the sun. These observations suggest that the oviposition period is related to light intensity. Copyright