A facultatively autogenous population of Cullicoides marmoratus (Skuse, 1889) was dominant at Deception Bay, 25 mls north of Brisbane, Australia as indicated by collections using truck trap and animal bait.
Truck trapping was more effective than light trapping and reasonable samples of all age grades were collected.
Population levels were depressed considerably in July when crepuscular activity was limited to evenings probably owing to reduced temperatures.
Emergence was related to the length of the gonotrophic cycle since it is thought that oviposition occurred during spring tide periods.
Duration of the ovarian cycle (time taken to mature follicles) lengthened from 72-96 hours in summer to 210-240 hours in winter.
Abdominal pigmentation was shown to be a, reasonably reliable method of age grading C. marmoratus as complete ovariolar degeneration occurred in less than 1% of specimens, pigment developed from either sugar or blood meals and was persistent. Production of the burgundy-red pigment was detected at Christopher’s ovary stage III in half the specimens, but by early stage IV, 96% of material studied was pigmented.
Ovariolar dilatations were found only in pigmented midges.
Pigment development, digestion and follicle maturation progressed synchronously.
The daily survival rates of 47.5% (January) and 75.6% (July) were confirmed by dissection results which showed that only 1 in 500 females had oviposited twice.
It was indicated that C. marmoratus would be a poor potential vector of disease despite the large population present and its wide powers of dispersal.