Did you know the Parramatta River Catchment holds the NSW record for the most number of mosquitoes collected in a single trap, as part of the NSW Arbovirus Surveillance Program? Close to 30,000 mozzies were trapped at Duck River, near where it joins Parramatta River, in February 2020. So yes there’s a very good reason for the slap, slap, itchy dance so many of us have with mozzies each summer around Parramatta River!
The humble mozzie is the world’s deadliest animal, killing over 700,000 people every year! Thankfully, the ones we have in in Australia won’t kill you – they’re just damn annoying and can make you sick. But you’ll be happy to know that with a bit of information you can reduce the chance of being bitten.
With the help of Associate Professor Cameron Webb, we’ve answered 25 frequently asked questions about mozzies and provided handy tips for reducing the chance of being bitten.
| Mozzies and Parramatta River | Top Tips |
FAQs (about mozzies, protecting yourself, reducing number of mozzies) |
Mozzies and Parramatta River
Unfortunately us Aussies have one thing in common with mozzies – we both LOVE living near water. And don’t we know it living near Parramatta River!! During summer, simple things like hanging out washing, taking the dog for a walk, playing at a local park and watering the garden will very likely have us doing the mozzie swat dance and being covered in bites.
But mosquitoes aren’t a new annoyance for anyone living along Parramatta River. Back in the late 90s, there was strong community outcry over mozzies. And thankfully there were a number of things put in place that made a big difference, including the regular spraying over the wetlands at Sydney Olympic Park.
Fast forward 20+ years and the number of people living along Parramatta River has grown by about 50%. And unfortunately this growth in people, along with the impact of the associated urban development on our natural environment, has been perfect for mozzies. In February this year, close to 30,000 mozzies were trapped near Parramatta River, along Duck River. This is a NSW record for the number of mosquitoes collected in a single trap as part of the NSW Arbovirus Surveillance Program. And partly explains why it’s hard to avoid the feeling of being bitten alive when we step outside!
It’s been easy to see the growing frustration about the mozzie situation in the community, particularly among parents. About a year ago, local mum Cindy Brown started an online petition calling on City of Parramatta and City of Ryde Councils to reduce the mosquito population. It got close to 500 signatures but unfortunately didn’t result in any action. The problem seems to lie in who is responsible for addressing the issue of mozzies…
We’re happy to report that through our advocacy, the Parramatta River Catchment Group has agreed to take the lead and bring the relevant parties together as a first step. Watch this space!
Top Tips for Staying Safe from Mozzies
Thankfully, there are some simply things you and your neighbours can do to reduce the number of mozzies around and chance of being bitten. So we invited the leading Australian expert on mosquitoes, Associate Professor Cameron Webb, to share his top tips and answers to your frequently asked questions.
Cameron is often referred to as the Mosquito Man, having spent the last 20 summers sloshing about in gumboots and chasing mosquitoes around the wetlands of Australia. We imagine he has also got a LOT of mozzie bites to show for it! He is a Clinical Associate Professor with the University of Sydney as well as Principal Hospital Scientist with the Department of Medical Entomology at NSW Health Pathology. And on top of this, he’s a local dad to two school aged children.
Cameron recently joined me live on the ParraParents Facebook page for an ‘ask me anything about mozzies’ session. You can watch it here (please excuse the technical glitch we had about 10mins in).
Frequently Asked Questions About Mozzies Answered
There’s lots to learn about mosquitoes once you go looking. By understanding them better, we can better protect ourselves and reduce the impact they have on us getting outdoors and enjoying summer!
With the help of Associate Professor Cameron Webb, here are answers to 25 questions commonly asked about mozzies. We’ve grouped them into 3 topics:
- Understanding Mosquitoes
- Protecting Yourself Against Mozzies
- Mozzies Not Welcome Here – Reducing the Number of Mozzies Around Your Home, School, Workplace, Parks and Waterways
1Why do mozzies bite?
Only the female mosquitoes bite. They bite us because they need blood. The blood provides nutrients to assist with egg development. So you could say that they’re just being good parents!
2Are all mozzies the same? And what types are found along Parramatta River?
There are dozens of different types of mosquitoes found along the Parramatta River. They are closely associated with a range of habitats from saltwater to freshwater to polluted storm-water drains and backyard birdbaths. Each mosquitoes prefers a particular type of habitat. The two most common mosquitoes are the saltmarsh mosquito (Aedes vigilax) and backyard mosquito (Aedes notoscriptus).
Most mosquitoes travel less than two kilometres from their original breeding place, though depending on the species they can travel from as little as a few hundred metres to 50kms. The ones around Parramatta River are known to travel up to 5kms away. So the large population of mosquitoes in Duck River could well be biting people from Putney to Holroyd and Telopea to Guildford!
4Why is water important to mosquitoes?
Mosquitoes spend about half their life in water and it’s essential for their development. They often look for wetlands and ponds to lay their eggs. But sometimes, anything that holds water – a bucket, bird bath, drain or rainwater tank – will do. When the larva hatch, they wriggle about in the water for a week or so before emerging to fly off in search of blood.
So the more water there is, the more mosquito eggs are laid. And the more mosquitoes end up buzzing about!
5When are mozzies worse?
Mosquitoes are around almost all year but they are especially active and abundant between December and March. And even then, populations of mozzies will go up and down, with peaks occurring about 2 weeks after ‘king tides’ or substantial rainfall.
Mozzies are also more active at dusk and dawn. So while watering your garden after dinner in the cool of night may be good for reducing water evaporation, you will very likely get covered in itchy mozzie bites.
6Why do mozzies seem to bite some people more than others?
It’s quite a romantic notion that the sweetness of our blood attracts mosquitoes. But the reality is that even though it’s our blood they’re after, there’s no strong evidence to support mozzies preferring one particular blood type over another. Most mosquitoes will get their blood from whatever is around and won’t necessarily care who they’re biting.
You may be surprised to learn that a mozzie picking you out of a crowd has more to do with your breathing and the smell of your skin! When they need blood, mosquitoes can pick up on the carbon dioxide we exhale. So if you’re exhaling greater volumes of carbon dioxide, you’re probably an easier target for mosquitoes. More than anything though, it’s about how you smell. Hundreds of chemicals are sweated out or emitted by our body’s bacteria. The cocktail of smells they create will either attract or deter mozzies.
7Why are mozzie bites itchy? And why do some people have worse bites than others?
When the mosquito finds a place to feed, she injects her proboscis into our skin. The proboscis is the mosquito’s long, sucking ‘mouth’. It doesn’t go very far in because it isn’t like a needle. The ‘mouth’ of a mosquito is like a flexible drinking straw that snakes around under our skin looking for a blood vessel to pierce.
To get the blood flowing, the mosquito injects saliva into our skin. This ‘mozzie spit’ helps the blood flow but it’s also what causes those raised, red, itchy lumps. Those ‘itchy bites’ are our body’s reactions to mozzie spit.
So just as we all react differently to food, chemical or environmental allergens, we all react a little differently to mosquito bites. You may just have a small red spot on your skin. But other people have large swollen lumps that can itch for what seems like forever.
Unfortunately, reactions to mozzie bites can often be worse in young children. Their little bodies haven’t had a chance to build up immunity so they’re more likely to react more noticeably than older children and adults. This adds an extra level of anxiety for parents. But the worst result of most mozzie bites is largely self-inflicted from scratching and getting a secondary infection.
The most important thing is to ensure that the bite site is kept clean and dry, and scratching is kept to a minimum. Most children’s reactions to mozzie bites will naturally become less dramatic as they get older.
8Can a mozzie bite make me sick?
We are lucky that the risk of getting sick from a mosquito bite along the Parramatta River is very low. In other parts of Sydney, and elsewhere in rural and regional area, Ross River virus can be transmitted by mosquitoes when they feed on the blood of an infected animal, such as kangaroos.
Elsewhere in the world, mosquito-borne diseases such as dengue and malaria can be deadly. And their role in spreading the viruses and parasites that cause these diseases is the reason why mosquitoes are considered the deadliest animal on the planet.
9Which animals like to eat mozzies?
Mozzies have a number of natural predators. During their larvae stage, fish and other aquatic animals eat them. And researches have shown that mosquitoes are less likely to lay their eggs in water where there are lots of fish. Then when mozzies are adults, bats, spiders and bats each them. So don’t go pulling down those cobwebs in your backyard! Interestingly, adult frogs aren’t really interested in eating adult mosquitoes at all.
10Are mozzies all bad?
It’s generally agreed that mozzies do more harm then good, given how many people die each year due to mosquito-borne disease. But what good they do and their place in the world is really not that well know.
We do know they serve as food for many species – the larvae are like nutrient-packed snacks for fish and other aquatic animals and the adults are a nutritious meal for birds, spiders and bats. Mosquito larvae also feed on waste products in the water – making nutrients such as nitrogen available for plants to thrive. Interestingly, they mozzies also pollinate flowers. And there’s hope that mosquito saliva may have some potential use for the treatment of cardiovascular disease. But whether these things would happen still without mozzies is not known.
Protecting Yourself Against Mozzies
11What’s the best protection against mosquitoes?
A topical insect repellent will provide the longest lasting protection against mozzies. Insect repellents you buy from the supermarket or pharmacy are safe and effective and can be used on children older than 3 months. Products containing diethyltolumide (commonly known as DEET), picaridin, and oil of lemon eucalyptus are all effective as they block the ability of the mosquito to identify you as a potential blood meal.
NOTE: for repellents to be effective, you must apply them a thin even coat on all exposed skin. A dab ‘here and there’ won’t be enough!
For babies younger than 3 months, cover their pram and cot with a mosquito net. There are also portable, foldable mosquito nets that you can take to a park or beach for your baby to rest and play in.
12What should I apply first – sunscreen or mozzie repellent?
Rub on sunscreen and then spray on mozzie spray. Make sure to read the instructions of your mozzie repellent and reapply as advised. You’ll also need to reapply after swimming and if you’ve been heavily sweating.
13Is there an alternative to mozzie creams and sprays?
You may not like the sticky feel on your skin but mozzie repellents are really the best way to stop mosquito bites. There are, however, a few other options available that can at least reduce the number of bites and are worth a try.
But you should skip the wrist bands and patches – they don’t work!
Battery-operated and ‘plug-in’ devices that release products that kill or repel mosquitoes, on the other hand, do work. These devices typically release an insecticide from a heated pad or oil reservoir. They can be useful when used indoors at night to stop the pesky buzzing. But there are also devices that can be taken on the go. Whether you’re clipping them to your belt or backpack or sitting them on your picnic table, they won’t provide an impenetrable shield against mosquitoes but they will at least keep some away.
14Do mozzie coils work?
The smell of mozzie coils reminds me of camping and Aussie summers! Mosquito coils and their role in preventing mozzie bites has been well studied. And it’s agreed that they will generally reduce the ability of mosquitoes to bite people.
Mozzie coils work in one of two ways. Those that contain insecticides will kill (or at least ‘knock down’) mosquitoes. While those that contain aromatic substances (such as citronella) will repel mosquitoes or reduce the likelihood they’ll bite.
15What else can I do to reduce the chance of being bitten?
On top of apply insect repellent and using mozzie coils, you should avoid outdoor areas during dawn and dusk as this is when mosquitoes are most active. Wear light coloured and loose fitting long sleeved shirt and long pants. Mosquitoes will be able to bite through tight fitting clothing such as active wear! Install insect screens on all windows and doors (where possibly) or sleep under a mosquito net.
16Is what I wear important in either attracting or keeping mozzies away?
There’s some evidence that shows mosquitoes are more attracted to dark coloured clothing, particularly navy. But wearing other coloured clothing won’t stop you from being bitten either – probably just reduce how many times!
Current evidence also suggests insecticide-treated clothing may reduce the number of mosquito bites you get, but it doesn’t offer full protection.
17Once bitten, what can I do to reduce swelling and irritation?
If you are prone to particularly swollen or itchy bites, the best way to soothe them is by applying a cold pack. This will help reduce the swelling. Putting on an anti-itch cream can also help.
Importantly, make sure to do your best not to scratch too much because as soon as you break the skin’s surface you run the risk of secondary infection. Oral analgesics or antihistamines may also provide relief for serious reactions (and can even help reduce your reaction in the first place if you take them before going somewhere you know mozzies will be active). But it’s best to discuss the most suitable products with your doctor or pharmacist.
Antibiotics are rarely required for insect bites alone – generally only if a secondary infection occurs.
18Can I eat or take anything that will make me less likely to be bitten?
There’s no evidence that what you eat or drink will prevent mosquito bites. Some food or drink may subtly change how many mosquitoes are likely to bite you but it won’t make that much difference. Eating bananas or drinking beer has been shown to marginally increase the attraction of mosquitoes but the results aren’t enough to suggest any dietary change will reduce your mozzie bites.
Same goes for taking vitamin B. There’s many anecdotal reports and personal testimonies of the effectiveness of this approach but there are few scientific investigations testing the claim. Studies dating back to the 1940s failed to provide proof of protection from mosquito bites after taking vitamin B. More recently, a 2005 study showed there was no evidence it influenced the attraction of mosquitoes to human skin-derived chemicals from volunteers taking vitamin B supplements.
In both cases, it why our supermarket shelves aren’t full of “mozzie repellent” pills.
Mozzies Not Welcome Here – Reducing the Number of Mozzies Around Your Homes, Schools, Parks and Waterways
19How can I stop mosquitoes from breeding in my backyard?
Mozzies are like the annoying relatives who come for a day and stay a few weeks! But you can win back your backyard by regularly tipping out, throwing away, or covering up any water-holding containers. Mosquitoes can breed in small volumes of water, such as a planter saucer, discarded drink bottle or even a tarpaulin covering a trailer.
Mosquitoes can also find a home in blocked roof gutters, drains, unscreened rainwater tanks, buckets or bins designed to catch and store rainwater. Water holding plants, especially bromeliads can be a great home for mosquitoes as well.
Mozzies also prefer shaded areas with little air flow. So if you have a particularly shaded spot, and a lot of mozzie housemates, you may want to think about giving the tree a little prune.
20What can schools and child care centres do to limit the number of mozzies?
Reducing the number of mozzies at a school or childcare centre is very similar to getting rid of them around your home. Follow these 12 steps to help keep students and teachers safe from mozzies.
- Empty out water holding containers each week
- Install insect screens on windows and doors
- Remove leaves and other debris from roof gutters
- Make sure water is not pooling in drain sumps. And if it is, you can either fill in the lower part of the pit with concrete or sand, or put a fine mesh over the grate. It’s also important to remove debris to improve water flow and you should also consider getting pest controllers to treat drain sumps during routine pest treatment.
- Install flap valves or mosquito-proof screens on rain water tanks
- Ensure there’s good airflow in the areas where children will be spending a lot of time
- Stay indoors in the early morning or late afternoon when mozzies are more active
- Reapply mozzie repellent throughout the day
- Leave cobwebs undisturbed where possible
- Look at purchasing outdoor mozzie repelling devices
- Avoid excessive insecticide as it can kill the insects that eat mosquitoes
- Avoid water holding plants (e.g. bromeliads) or flush them out with a hose once per week
21Does litter have anything to do with the level of mozzies around Parramatta River?
Litter, such as plastic cups, plates and even plastic lids, can provide a lovely spot for mozzies to breed when they have water in them. Plus mozzies like stagnant water, so if litter is blocking the flow of water in our creeks, then this also creates attractive spots for mozzies to breed. Sadly there’s a lot rubbish clogging up Duck Creek in particular, as well as along Duck River and plenty of litter along the foreshore of Parramatta River.
In just the last year, we’ve removed over 200 Clean Up Australia Day bags of rubbish along Parramatta River with the help of wonderful local families. Please join us in helping make Parramatta River litter free and also reducing the annoying mozzie population by picking up a few bits of litter when you are out along the river.
22Where are mozzies worse along Parramatta River?
Based on current evidence, Duck River is a particularly good breeding ground for mozzies. In February this year, close to 30,000 mosquitoes were caught in a trap there, near the end of Holker Road in Clyde. To put this in perspective, the most mozzies collected in a trap at Sydney Olympic Park is about 10,000. There were very large numbers prior to the commencement of the spraying program. We occasionally now get 1,000-2,000 per trap during summer. This is pretty consistent with the fact that we get about 85-90% reduction in mozzie numbers following treatment.
There will be mozzie surveillance carried out this summer in the City of Canada Bay. And we’re hoping City of Ryde will also participate so we can get a fuller picture of the types, levels and movements of mozzies along Parramatta River.
23What is the role of mangroves when it comes to mozzies?
Mangroves provide a range of services to the surrounding ecosystem and to people lucky enough to live near them. They’re extremely effective at protecting the shoreline from erosion by gripping the soil in their complex root systems. Mangroves also filter sediment out of the water that flows over them. Plus they are great at storing carbon – two to four times better than tropical rainforests.
But mangroves have an almost fatal flaw – they prefer waterfront property just as much as us humans. And urban development has eaten away at them, leaving mangroves highly endangered. They are also regularly blamed for all our mozzie woes along Parramatta River. Yes mosquitoes are a natural part of wetland ecosystems. But there’s actually evidence to suggest that degraded mangroves are more productive when it comes to mosquitoes. So improving our wetland habitats is also central to reducing the level of mozzies along the Parramatta River.
24What is the Sydney Olympic Park mosquito management program? And why is there spraying only at certain times and locations?
Sydney Olympic Park Authority (SOP) undertake an annual program of aerial and ground spraying to reduce mosquitoes on lands under their care. The aim is to improve the comfort of people living, visiting and working in the area, particularly Newington and Wentworth Point.
SOP contains extensive wetland and saltmarsh areas, which are natural breeding habitats for saltwater mosquitoes. The SOP mosquito management program involves the application of a bacterial larvicide containing Bti (Bacillus thuringiensis israelensis), which is considered safe for humans, pets and other fauna in the environment. The bacterial larvicide is sprayed on some of the mangrove forest and saltmarsh areas at SOP. A number of factors influence when and if the spraying occurs, including tides and rainfall as well as the availability of the helicopter (in 2019 it was required to help bushfire efforts). You can see the schedule of spraying for 2020/21 here.
As well as coordinating treatment of wetlands to control mosquitoes, there’s a program of wetland rehabilitation underway that will hopefully provide a long-term reduction in mosquito populations without reliance on spraying in future.
Due to other areas along Parramatta River being governed by different authorities, they would have to organise and fund a similar program for more wider spread spraying to occur. And there are restrictions with the location of power lines.
25What else can I do to help reduce the number of mozzies around?
A great, simple way you can help is to let your neighbours and their neighbours know what need to do so mosquitoes aren’t welcome in their backyard. Because a fence isn’t going to stop a mozzie. They’d happily jump over to your neighbours bucket of rain harvested water! Please also share these tips and FAQs with your school, child care centre and workplace.
And if you are really keen to help, join Mozzie Monitors! There just aren’t enough resources to set mosquito traps everywhere. But knowing where mozzies are and in what numbers is very important for public health campaigns. This is where Mozzie Monitors comes in. It’s the first citizen science program in the world which combines mosquito trapping with community participation. Volunteers set up cheap and simple mosquito traps in their backyards. Then using their smartphones to send back data on the caught mosquitoes. You can also take photos of mozzie activity and send it in via iNaturalist.
If you would like to learn more about mosquitoes in Australia, Cameron Webb has co-authored a book, published by the CSIRO.