Don’t use nasty sprays; use fly screen to keep them off…
In defence of mosquitoes, Darwin’s unsung urban planners
You might imagine a world without mosquitoes as some kind of nirvana, devoid of itchy bites and self-inflicted arm slaps. More seriously, their absence could spell the end of malaria and dengue fever. But anthropologist Tess Lea says they’re actually an integral factor of life as we know it.
It’s easy to despise the humble mosquito. On top of being a general nuisance, they kill between 600,000 and 700,000 people every year, infect around 200 million more, and cost billions of dollars in lost productivity. They’re like the lionesses of the sky.
Among the deadly pathogens they carry, such as malaria, dengue fever and yellow fever, we can now add one more: Zika virus, which has swept across Brazil, and can cause deformity in unborn children, amongst other things.
Other than humans killing other humans during wars, most years, the mosquito wins as deadliest creature on the planet.
But to anthropologist Tess Lea, author of the new book Darwin, mosquitoes aren’t all bad. In fact, she describes them as the unsung urban planners of her home town.
A born and bred Darwinite, she knows a thing or two about mozzies. She’s also studied them from the vantage point of an anthropologist: how they impact on their local ecosystem, and culture more broadly.
While she acknowledges the impact mosquitoes can have on human health, Lea says they defined how Australia was settled, and still impact city planning today.
‘Mosquitoes played a role in saying where settlement couldn’t be,’ she says. ‘Mosquitoes knocked off the first four attempts.’
Lea says their presence helped protect mangrove swamps and some ‘pretty important’ Aboriginal country.
She also argues that in the case of Palmerston, a new satellite town built to fill demand for low income housing in Darwin, concerns about mosquitoes saw residents receive superior water infrastructure that they wouldn’t have otherwise. The drainage in Palmerston is superior to that in Darwin itself, Lea says.
While the entire mosquito family is usually maligned, Lea says it’s just a dirty dozen who give the rest a bad reputation. Of about 2,000 mosquito species, only 80 bite humans, and even then it’s only the females when they are breeding.
‘They’re like the lionesses of the sky,’ Lea says.
The males, along with females outside of breeding times, tend to flowers and plants, much as bees do. In fact, some plants like the blunt-leaved orchid and endangered monkey face orchid rely on mosquitoes as their primary pollinator.
An important ecological player
If all mosquitoes were eradicated, many species of birds, insects, spiders, lizards, frogs and fish would lose a food source, Lea says. The insects also play an important role in pest control: some mosquito species eat others, and they are an essential food source in the mangroves.
‘In our cities the mangroves are the last remaining wilderness spaces that we actually have,’ Lea says.
‘For the mosquitoes and the fish and the frogs and the birds that all are a part of those ecosystems, we lose the lot, potentially, if we just decide, no, let’s take the sledgehammer attack.’
‘Plus, they’re the main food source for dragonflies. Who could possibly want to eradicate dragonflies?’
The biggest ecological impact of eradicating all mosquitoes, Lea says, would actually be in the Arctic tundra.
‘That’s where mosquitoes have a massive ecological role to play,’ she says.
‘It turns out they have this tiny window to breed and when they do they swarm like fury and they eat like fury.’
Trying to escape the mosquitoes, the caribou head into the wind and are effectively herded across the tundra.
‘If you took [mosquitoes] out of the tundra, what that would mean is that the caribou are not going along these reliable routes,’ Lea says.
‘So the things that hunt the caribou, which would include wolves and other hunter gatherers, also lose a pretty important food source.’
A complex creature
While Lea admits it’s hard to defend an animal that has the potential to kill people, she just wants people to hesitate about the idea of a complete cull.
‘There’s a small number who end up being involuntary hosts for pathogens that kill humans,’ she says.
‘However, in our clumsy attempts to eradicate them we would be rather more indiscriminate and we’d take out the lot, plus adjacent species—you know we would—and we wouldn’t apologise for the ramifications.’
Lea says she is enchanted by mosquitoes, calling them ‘angels in the sky’.
‘I know how annoying they are sure, but let’s think about that complexity,’ she says.
‘If you start to look at their flight paths and how … that female mosquito full of blood, she’s just quadrupled her body weight but she’s still able to lift—think of the aeronautical engineering in that alone.
‘This is a species that has been around since the Jurassic period. I mean, we’ve been around for like one second in comparison.’