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April 2020 Issue
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Bite me for science

Photo: Rachael Hockridge
Te Papa’s curator of invertebrates Julia Kasper is leading a mosquito census and wants your help in determining the distribution and number of mosquito species around New Zealand. She explains the method to her madness to Alistair Hall

Why a mosquito census – anyone can tell you there’s too many?
Our insects are in decline and we want to know what’s happening.
Mosquitoes are a good model organism because the public is aware of them much more than they are of a little beetle that is hidden under leaves. We have 13 native mosquitoes in New Zealand and three introduced species. There are some native species doing OK but there are others that are so unique and so adapted to special circumstances that we don’t see them very often and we don’t know what is going on because we don’t have the data. We suspect they are endangered and before they disappear we want to know what is going on. And these mosquitoes are not a nuisance.

What do you mean, they’re not a nuisance?
Before humans arrived there were no mammals in New Zealand apart from bats and seals, so [the native bush] mosquitoes are more adapted to biting birds. If birds aren’t around but there are some trampers in the bush, they wouldn’t mind biting the trampers, but they’re not their first choice. There is a big difference with the introduced ones which are much more vicious. Still, it’s hard to feel sorry for them. Why should we care if they’re in decline or go extinct?

There are 3000 mosquito species in the world and only a small percentage of those bite mammals, including us. And only a small percentage of those biters are able to transmit diseases. So all these other species are neglected and people don’t like them because of the small percentage of bad ones. The reality is they are important for our ecosystem. We cannot just eradicate them because everything would collapse without them. They are pollinators, they are a super important part of our food chain and the larvae help clean waterways.

You want people to freeze mosquito specimens and send them to you. Can’t they just squash them?
Mosquitoes have scales similar to a butterfly and this pattern is what is needed to identify the species. If you squeeze one, the scales will be scattered all over the mosquito and we won’t be able to identify it.

Can trampers help by capturing a mosquito at a hut or in remote bush?
I can’t ask people to collect from DOC land because you need a permit to do that. Even for sandflies. But there are other areas in the bush that are not nature reserves and from those areas I would really, really love to have some samples.

Where can people best find a mosquito to send you?
It really depends on the species. Some species are container breeders and I’m definitely interested in larvae as well. It’s mostly the introduced mosquitoes that breed in artificial containers like plant pots and used tyres. Native container breeders lay eggs in leaf axils and tree holes. Other species breed in rockpools, ponds, puddles, even salt marshes. In terms of adults, look anywhere that is cool and shaded. If you leave the light on and the window open in the evening, that’s a good way to attract them.

You must get a lot of mosquito bites in your line of work?
I wish I had more because I’m rearing them and to make them lay eggs they need blood. I’ve put my hands in and those stupid mosquitoes wouldn’t bite me. Some people are more attractive than others, but we still don’t know everything about the chemicals that repel or attract them. I’m definitely not really attractive.

Have you found a surefire way to repel mosquitoes?
If you want to avoid them, everything that has DEET in it. All that citronella stuff, there’s a lot of myths and anecdotes around it and it might be like a tiny repellent but it’s very local – basically in that area where the candle is. Mosquitoes are also very attracted to dark colours, so if you want to avoid them you should wear light colours.