Like all insects, mosquitoes breed in warm weather. But what they really need is water. La Niña rains and flooding provide the perfect breeding ground for mosquitoes, whose numbers have increased in recent weeks.
People also see giant mosquitoes, small mosquitoes, and species they didn’t notice before. Some of these mosquitoes are present in every season, but due to favorable conditions, their numbers increase.
There are about 300 species of mosquitoes in Australia. So what should you look out for?
First, let’s go over some mozzie basics.
Mozzies live for about 3 weeks
The life cycle of mosquitoes is complex. Eggs are laid on or around water. Immature mosquitoes are completely dependent on water when they hatch.
During the warmer months, it may take up to a week for an adult mosquito to emerge from the water to start buzzing and biting.
Adult mosquitoes live only three weeks.
Only females bite
Mosquitoes need blood as well as water and warmth. But only female mosquitoes bite because they need extra nutrition to help the eggs develop.
Mosquitoes don’t just bite people. They will bite a wide variety of mammals, birds, reptiles and amphibians. They can even bite earthworms, mudfish (amphibious fish) and even whales.
What are ‘giant’ mosquitoes?
It is a mosquito that never bites in Australia Toxorhynchites speciosusA “giant” mosquito common in eastern Australia.
The mosquito is a predator: their “grubs” often eat the mosquitoes of other pest mosquitoes. Closely related mosquitoes have even been used for mosquito control in other states.
But it is not these “friendly” mosquitoes that cause all the problems after the flood.
Other mosquitoes, commonly known as “floodwater mosquitoes,” can bite and are found in large flocks after flooding. They are a serious concern. Examples of these mosquitoes include Aedes sagax, Aedes vittigerand Aedes aculeatus. Often they disappear as quickly as they appear.
Mosquito control programs such as the NSW Arbovirus Surveillance and Mosquito Monitoring Program are already picking up these mosquitoes (and many smaller species) this season. Perhaps the most famous of them is the large, sandy mosquito Aedes alternans. Commonly known as the Hexham Grey, poems have been written about this mosquito and there is even a “big mozzie” in Hexham, NSW.
Which mosquitoes make us sick?
Despite the diversity of mosquitoes in Australia, only a few pose a serious threat to public health.
Aedes notoscriptus mosquitoes have left their natural habitats and adapted to life in containers filled with water around our homes. In addition to transmitting the viruses that make us sick, they have also proven troublesome pests.
In the coastal regions of Australia, Aedes vigilax (commonly known as salt gnat) and Aedes camptorhynchus (commonly known as southern saltwater mosquitoes) are found in estuarine marshes. These include mangrove and salt marsh habitats where water is often brought in by “king tides”. Mosquitoes tolerate salty conditions. These mosquitoes can appear in large numbers in the summer, bite aggressively and fly many kilometers over wetlands. They are also the mosquitoes responsible for the spread of mosquito-borne diseases in coastal areas due to their ability to spread Ross River virus.
A number of pest mosquitoes are found in freshwater marshes. It is the biggest pest Culex annulirostris (commonly known as striped freshwater mosquitoes). This mosquito is found in a variety of habitats, from wetlands to stagnant ponds. Striped freshwater mosquitoes are probably the most important species when it comes to spreading pathogens such as Ross River virus, Murray Valley encephalitis virus and Japanese encephalitis virus.
How can we overcome their bites?
After three years of below-average rainfall and recent flooding, much of eastern Australia is home to just one giant mosquito. While some efforts to use insecticides to control mosquitoes may be effective, the reality is that the task of adequately controlling mosquito populations is insurmountable.
Here are some steps you can take to protect yourself and your family from mosquito bites. When outdoors, wear a loose long-sleeved shirt, long pants, and covered shoes. You can even treat your clothes with chemicals like permethrin or transfluthrin.
Insect repellents also provide protection. Products containing deet, picaridin, or lemon eucalyptus oil will provide the longest protection, but ensure you cover all exposed areas of skin.
Mosquito coils and other products can help when combined with repellents.
Now the bad news. Flooding may pass quickly, but water will remain in pools and ponds across much of eastern Australia for much of the summer. That’s great news for mosquitoes, but not so good for those of us already nursing arms and legs full of scabby red mosquito bites.
Cameron Webb, Clinical Associate Professor and Senior Hospital Scientist, University of Sydney
This article is republished from The Conversation under a Creative Commons license. Read the original article.