Previous investigations of biting insects in the Palmerston area have been made by consultants in conjunction with the Medical Entomology Branch or by the Medical Entomology Branch. The results of these investigations revealed considerable biting midge numbers associated with the mangroves on the west side of Palmerston and particularly in the southern area associated with the mouth of the Elizabeth River and the northern area associated with the east arm of Hudson Creek. The latter investigation indicated that the principal biting
midge species Culicoides ornatus, disperses in relatively high numbers at least 1.5 km from the mangrove margin, with the highest numbers found within 1. 0 km from the mangrove margin.