Aotearoa's buzzing! Meet our endemic mosquitoes

This series was created in conjunction with Auckland Zoo ectotherm keeper Ben Goodwin, to shine a light on Aotearoa’s precious native invertebrates and discuss the actions we can all take to help them.

In the latest of our blog series on the fascinating world of invertebrates we’re focusing on a group of more than 3,500 species which make up the Culicidae family. Their name is Spanish for ‘little fly’ and you’ll often hear them before you can see them. That’s right, we’re talking about mosquitoes! You may be surprised to learn that there are 16 species of mosquito that live in Aotearoa and in this article, we’ll be telling you more about them. 

Earth is home to thousands of mosquito species and these ‘little flies’ were around long before humans evolved. In fact, scientific evidence suggests that mosquitoes first came on the scene as far back as the Jurassic Period - that’s 200-150 million years ago - and could have even fed on the blood of dinosaurs. So Jurassic Park got that part right! A primitive version of the modern-day mosquito was found in Burmese amber that dates back almost 100 million years ago, while a 46 million-year-old mosquito fossil was found preserved in shale rock in Montana, USA. In comparison – the oldest human fossils on record date back a relatively short 200,000 years ago.

So, what has millions upon millions of years of evolution created? An incredible organism naturally engineered to breed rapidly, manoeuvre quickly in the air and easily find its next meal. Mosquitos are equipped with a pair of wings, a pair of halters (small vibrating organs that help the mosquito interpret and correct its position during flight), three pairs of legs, and a long, slender proboscis - an elongated, tube-like mouthpart which it uses to eat, and in some cases, suck blood.

Like most insects, the mosquito has four distinct metamorphic stages in its life cycle – the egg, an aquatic larval and pupal stage, and a flighted adult stage. Depending on the species, the female will lay her eggs individually or attached together to form rafts that float on the surface of the water. Alternatively, she might cleverly deposit them in an area that will become flooded after rain, like a patch of mud that will later turn into a puddle.

Most of these eggs will hatch into larvae within 48 hours and kickstart a period of intense growth. These larvae feast on microorganisms and organic matter by using their brush-like mouth parts, aiding the decomposition of vegetation and other debris as it falls into the water. Each larva sheds its skin multiple times, growing larger after each moult, before changing into a pupa. The metamorphosis of mosquito pupae is comparable to that of adult butterflies emerging from a chrysalis. At exactly the right time, the pupal skin will split and the newly metamorphosed adult mosquito pulls itself out, before resting on the water’s surface, allowing it’s wet, wrinkled wings to spread out and dry, and then flying away.

So, what does an adult mosquito eat? You’ll be pleased to learn that only select mosquito species require blood as part of their diet, and of those that do, there are fewer still that would choose humans as a blood source. In fact, the main diet of mosquitoes is nectar, and although they don’t gather pollen like bees, their nectar-seeking flight path helps to pollinate the flowers they visit. Just one of many important roles they play within an ecosystem. When blood is required, it’s the females exclusively that will seek it out, utilising the protein and iron to produce their eggs.

As many of you will no doubt have experienced when camping or barbequing outside during the warmer months, a mosquito bite can result in a slight itch, but generally causes no harm to you. This itchiness comes from the mosquito's saliva which is transferred to your skin when the bite occurs. It’s in this way that some mosquito species can transmit infectious pathogenic microorganisms from one living host to another. Pathogen-carrying agents like mosquitoes, are known as vectors. Zika, dengue, chikungunya, and yellow fever are all transmitted to humans unwittingly by one particular species of mosquito, the Aedes aegypti. Malaria, one of the most deadly diseases in human history is spread by mosquitoes in the genus Anopheles, infamously regarded as the most dangerous (non-human) animals on the planet and responsible for the death of several hundred-thousand people every year (although it’s not actually the mosquitoes which are deadly of course, but the malarial protozoan parasite Plasmodium sp.). Thankfully, these mosquito species and their parasitic passengers don’t occur in New Zealand.

So, what of our native mosquitos? Of the 16 species that currently call New Zealand home, 13 are endemic, which means that they evolved here and are found nowhere else in the world. While these are formally described (named and known to science) they are currently understudied, so little is documented about them. In te reo Māori mosquitoes are known as waeroa and there are several pūrākau (traditional stories) that speak to their origin and feats, as well as plant-based rongoa (medicine) used to treat their bites.

Aotearoa also has three non-native species that were accidentally introduced here and have found this environment most hospitable. Thought to be brought here as stowaways on American whaling ships, Culex quinquefasciatus arrived in the 1830’s and is now found from Northland to mid Canterbury; Ochlerotatus notoscriptus, the stripy-legged species you’re most likely to have been bitten by, has been disrupting Kiwi picnics since 1918; and Ochlerotatus australis which set up camp in the lower South Island sometime prior to 1962 and which some regard as a self-introduced (and therefore native) species, which we share with Australia.

There was also a fourth species, Ochlerotatus camptorhynchus, the southern saltmarsh mosquito from Australia, that was first detected in New Zealand in 1998. A species that readily attacks humans and is a known vector of several diseases, it was subsequently eradicated by New Zealand’s Ministry of Health between 1999 and 2000.

The most common native mosquito found across the breadth of the country as well as the sub-Antarctic islands is Culex pervigilans. This is the high-pitched-buzzing mosquito which flies-by-night to disturb our sleep every summer. One of the reasons why they’re so common is that the larvae and pupae of this species are able to accommodate a wide variety of conditions, allowing them to thrive nearly anywhere where standing or slow-moving water is present. The main hosts of these mosquitoes are birds and the occasional cow, but luckily for us they don’t often bite humans (although their nocturnal buzzing is equally irritating).

Culex asteliae is one of our smallest endemic mosquitos. It was first discovered on Auckland’s Rangitoto Island in the late 1960’s and has since been found from here up to Kaitaia and out to the Coromandel peninsula. Its species name ‘asteliae’ refers to the plant Astelia hastata, also known as kahakaha or widow-maker. A very large and distinctive epiphyte with rigid, fanning leaves, the bases of which form a V-shaped cup where water and leaf-litter collect (much like they do in exotic bromeliads). Within this small reservoir, the female mosquito lays her eggs and the larvae can develop in an area largely free of predators. Kahakaha usually grows attached to large trees, often well up in the canopy, it’s here too that these mosquitos live. The larvae of Culex asteliae have been found living up to 18 meters above the ground, nestled within the plants.

Another endemic species, Culex rotoruae or the Rotorua mosquito, has developed a highly specialised breeding strategy. It will only breed in mineralised, geothermally heated waters and lives within the Taupō volcanic zone, Rotorua, the Waiwera stream north of Auckland and at Ngawha Springs in Kaikohe. Little is known about this mosquito but research by Te Papa entomologist Julia Kasper confirmed that it’s larvae can survive in water temperatures of 34.4 degrees Celsius. They could exist in temperatures even higher than this but accessing the hottest areas of these lakes proves difficult. The lack of predators and the ability to breed all year long could be the reasons why this mosquito species has adapted to live in these extremely hot areas.

The biggest and, perhaps most distinctive mosquito in Aotearoa is Opifex fuscus or the saltpool mosquito. Found on rocky coastlines, it breeds above the high watermark in brackish or salinised rock pools which is a unique behaviour for mosquitoes (and very rare for insects, in general). Sun-up or sun-down this species is known to give us humans a painful bite, but its natural hosts are thought to be seabirds and coastal mammals like the New Zealand fur seal. One of the most fascinating traits about this species is its breeding patterns. In the warmer months, each breeding pool is scattered with adult males searching for emerging females. Living within these rockpools are pupae, ready to breach the surface of the water to complete their moult into adult-form. As soon as one is spotted, the long-legged males will dart across the water’s surface to grab it with the long claws on its forelegs. Once secured, and often after battling off rival males, the male will attempt to mate with the pupa as it is moulting into maturity. If the moulting pupa is female, by the time she has emerged into her adult life-stage mating has already commenced. Sometimes the moulting pupa turns out to be another male, in which case the mating attempt is abandoned, and the adult male will start his hunt again.

Though under-researched, there is evidence that some of our native mosquito species are in decline This is worrying because, like all insects, mosquitos are vital for the health of our ecosystems. For example, mosquitoes are an important food source for our native animals. Birds, reptiles, bats, and invertebrates feed on the flying adults; and other birds, fish and aquatic insects relish the larvae.

Furthermore, our 13 endemic mosquitos are fascinating and unique members of our fauna. They’re as distinct as our birds and just as behaviourally interesting (even more, some would argue). Even though they bite us sometimes and keep us up at night with their incessant buzzing, they are still special creatures, worthy of our attention and admiration.  Minor irritation is a small price to pay for rich biodiversity.

Stay tuned for the next blog in our series, and if there’s an insect you’d like to know more about, flick us an email at zoonews@aucklandzoo.co.nz.

Our special thanks to Manaaki Whenua - Landcare Research for allowing us to take photos in the New Zealand Arthropod Collection. We’d also like to thank the following contributors for the photographs supplied for use in this blog - Bryce McQuillan, Nick Goldwater, Lek Khauv, Mike Lusk and Ben Goodwin. Individual photo credits are listed in the gallery above.