The common New Zealand midge occurs throughout the country and is associated with most freshwater rivers and lakes. The adult is attracted to light and can be a serious nuisance at night time in houses which are close to water. Midges do not bite, nor do they act as vectors for any disease. They breed throughout the year but most prolifically in summer. The larval stage is the so-called “blood-worm” which is common in the mud at the bottom of most freshwater areas. Large-scale breeding, which will produce adults numerous enough to be a nuisance to humans, occurs in large shallow lakes. Thus, for example, Lake Ellesmere in Canterbury and the man-made shallow oxidation ponds associated with sewage purification works as in Auckland, are renowned sources of plagues of midges. The adult midge is about 5 mm in length and has a superficial resemblance to a mosquito. Adults fly at dusk on calm nights in mating swarms but during daylight hours they rest and hide in vegetation near their breeding sites.
by Roy Alexander Harrison, D.SC., Senior Lecturer in Agricultural Zoology, Lincoln Agricultural College.