AbstractA facultatively autogenous population of Culicoides marmoratus (Skuse, 1889) was abundant at Deception Bay, 40 km north of Brisbane. Truck trapping and collections using bait animals were more effective methods of collection than light trapping. Population levels were depressed considerably in July when crepuscular activity was limited to evenings. The time of adult emergence shifted seasonally in relation to the tidal cycle. This shift was related to the duration of the ovarian cycle in winter and summer conditions. Abdominal pigmentation was permanent once developed. This provided and reliable criterion for age grading C. marmoratus. Pigment development, digestion and follicle maturation progressed, with few exceptions, synchronously with time. C. marmoratus in this area would be a poor vector of disease owing to its low estimated daily survival rate.