Story: Sandflies and mosquitoes
Page 2 – Mosquitoes
New Zealand mosquitoes
New Zealand has 16 species of mosquito, known to Māori as waeroa. Twelve are endemic (unique to New Zealand) and four are introduced. They are about 5 millimetres long and, as with sandflies, only the female bites (the males feed on flower nectar). Some areas – especially around swamps – are notorious for their swarms. One site north of Haast, on the West Coast, is called Mosquito Hill.
In her book Through South Westland (1911), traveller Maud Moreland described a desperately uncomfortable night in the Blue River Hut. She and her companion slept little and in the morning their hands and faces were swollen. Today, tramping huts in such blighted areas often have insect mesh over any opening windows.
Very little is known about New Zealand’s mosquitoes, and much of the current knowledge is anecdotal and speculative. Most of the 12 native species of mosquito seem to primarily feed on birds, although some species bit humans, especially Coquillettidia iracunda.
The other biting species are Culiseta tonnoiri and Aedes antipodeus.
The most common native species is the vigilant mosquito (Culex pervigilans). It is commonly found around Auckland city, where it enters houses. A night-time feeder, its high-pitched buzzing and biting can disturb the sleep, although it rarely bites humans. The larvae are likely to be found in any container that collects rainwater, such as old tins or bottles. The larvae are known as ‘wrigglers’, as they often wriggle to the surface to breathe.
- Culex pervigilans is the most widespread species, which seems to be because the larvae occur in a wide range of habitats.
- Culex asteliae occurs only in the northern North Island.
- The Rotorua mosquito (Culex rotoruae) is found only around Rotorua.
- Culiseta novaezealandiae is found only in south-east Otago.
- Culiseta tonnoiri occurs on the South Island’s West Coast and in the far north of the North Island.
- Aedes subalbirostris is restricted to Otago’s east coast, Southland and Stewart Island.
- Aedes chathamicus is endemic to the Chatham Islands.
The remaining five endemic species are reasonably widespread throughout New Zealand.
There are four introduced mosquito species. Three of them regularly bite humans.
Named for the white bands on its legs, the silent striped mosquito (Aedes notoscriptus) was first noted in Auckland in 1916 and probably arrived from Australia. It is the mosquito most often seen in the North Island and females may bite during the day and at night. In the South Island the species is thought to occur only in Nelson, Marlborough and Christchurch.
Brown house mosquito
The brown house mosquito (Culex quinquefasciatus) is native to warmer parts of the Americas. It is thought to have arrived via the water supplies of American whaling ships, probably in the 1830s. It is found around North Island ports and occurs as far south as Marlborough. It readily bites people, and lays its eggs in standing water around houses (for example, in guttering, bird baths and septic tanks).
New Zealand only has 13 sandfly and 12 mosquito species that are native. Similar-sized countries with temperate climates have more: Japan has 65 species of blackfly (sandfly), and 67 mosquito species; England has 32 species of mosquito. The reason may be New Zealand’s evolutionary history – there were no land mammals apart from a few bat species. In other lands, there were many large mammals for blood-sucking insects to feed on.
Southern saltmarsh mosquito
The southern saltmarsh mosquito (Aedes camptorhynchus) arrived around 1998. It was first found in swamp land near Napier, after complaints of its vicious biting. In its native Australia, this species can carry the Ross River virus and other diseases. Despite an eradication campaign, the insects have shown up in other parts of Hawke’s Bay, and in Gisborne, Northland and Marlborough. Eradication seems to have been successful in Napier, and similar schemes are in place in other areas.
The saltwater mosquito (Aedes australis) probably arrived at southern New Zealand ports on timber ships from Australia. It was first recorded in Stewart Island in 1961, and is also found in Southland, Otago and Westland. As this species does not stray far from coastal rock pools, it does not often bite people. Females do not need a meal of blood in order to lay eggs.