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Inspired by the pristine lotus leaf, Australian scientists have engineered a quickly biodegradable yet self-cleaning plastic they say is ideal for packaging fresh and takeaway foods.

If successfully commercialised, the wholly compostable product would help reduce the almost 80 per cent of plastic waste left to accumulate as landfill or sloughed off as a litter.

Like the foliage of the Nelumbo nucifera blossom, the synthetically-engineered substance repels liquids and dirt, making it suitable to meet hygiene standards.

Once discarded, it then breaks down rapidly in the soil.

Lead author of the RMIT University project, PhD candidate Mehran Ghasemlou, says the bioplastic was created with mass production in mind.

"Plastic waste is one of our biggest environmental challenges but the alternatives we develop need to be both eco-friendly and cost-effective to have a chance of widespread use," he said.

"We designed this new bioplastic with large-scale fabrication in mind, ensuring it was simple to make and could easily be integrated with industrial manufacturing processes."

Although strong, the product is made from cheap and widely-available starch and cellulose to keep production costs low and support biodegradability.

Unlike other compostable plastics, its fabrication doesn't require heating or industrial processing and would be simple to upscale to a roll-to-roll production line, Mr Ghasemlou says.

Neither does the new plastic need industrial intervention to biodegrade, with trials showing it breaks down naturally and quickly once exposed to bacteria and bugs in the soil.

"Our ultimate aim is to deliver packaging that could be added to backyard compost or thrown into a green bin alongside other organic waste," Mr Ghasemlou said.

"The food waste can be composted together with the container it came in, to help prevent ... contamination of recycling."

Lotus leaves are known to have some of the most water-repellent surfaces on Earth and are almost impossible to get dirty.

The secret lies in the leaf's surface structure, which is composed of tiny pillars topped with a waxy layer.

Water that lands on the leaf remains as droplets that roll off with the help of gravity or wind. They also sweep up dirt as they slide.

To emulate the effect, the RMIT team imprinted the surface of the plastic with a pattern that mimics the structure and coated with it a protective layer of PDMS, a silicon-based organic polymer.

Tests show it not only repels liquids and dirt effectively, it retains its self-cleaning properties after being scratched with abrasives and exposed to heat, acid and ethanol.

Co-author of the research Professor Benu Adhikari says the design overcomes the key challenges of starch-based materials.

"Starch is one of the most promising and versatile natural polymers but it is relatively fragile and highly susceptible to moisture," he said.

"Through our bio-inspired engineering that mimics the 'lotus effect', we have delivered a highly-effective starch-based biodegradable plastic."

© AAP 2022

Australia's east coast is being plagued by mosquitoes due to hot, humid and windy conditions caused by La Nina, experts say.

David Bock, an insect specialist at the Australian Museum, says seasonal mugginess has made things perfect for breeding insect populations.

"Mosquitoes are one of those insects that can breed really quickly and they love this moist warm wet weather," he said.

"The humid conditions are perfect for breeding and when stagnant water stays around long enough, they mate and lay their eggs on it.

"They might be in puddles, backyards and buckets and it only takes a few weeks for that whole life cycle to happen. The nymphs, or wrigglers, spend about a week in the water before being able to fly off."

While there are many different species of mosquitoes, Mr Bock says there are only a couple where the females suck blood, which helps provide the protein needed for egg development.

Following January's humidity, families from Queensland's north to Tasmania are being hassled by swarms that would normally be more at home in a tropical rainforest.

Desperate Sydney mum Sarah Mintz Schneiderv says she and he one-year-old, Laura, were so badly attacked in Dover Heights last week, the tot was covered with more than 30 bites across her face, arms and hands.

"It was horrific," she said.

"They were all over her face, arms, fingers, wrists and down both sides of her arms.

"She had a terrible reaction to them. The bites came up really red and angry, and kept swelling up for hours."

The speech pathologist has turned to a natural moisturiser to soothe Laura's bites.

"She also gets eczema, so we used the MooGoo Eczema and Psoriasis Cream on her and it instantly calmed her skin," Ms Schneiderv said.

"It immediately alleviated the redness and helped the bites dissipate."

Chief executive Melody Livingstone says sales of the cream is up 23 per cent and MooGoo's Tail Swat natural insect repellent up 14 per cent.

"The mozzies are out in force this year," she said.

"We've been inundated with people asking what can help soothe their bites."

University of South Australia researcher Stephen Fricker says humid conditions along the eastern states are perfect for "a monster month of mozzies".

UniSA has launched the fourth edition of its citizen science initiative Mozzie Monitors to track and monitor mosquitoes in urban areas in a bid to predict and mitigate disease risks.

© AAP 2022

Politicians making last-ditch pitches were abundant but snags few and far between as voters headed to the polls in four NSW by-elections.

Four months after former premier Gladys Berejiklian's sudden resignation prompted three other MPs to follow suit, polling day finally arrived on Saturday in Bega, Monaro, Strathfield and Willoughby.

While about 40 per cent of constituents in the electorates had already picked their candidate - voting early or via post - people turned out to booths saturated with signage throughout the morning.

Premier Dominic Perrottet made campaign pit stops in both Sydney seats, Strathfield and Willoughby, while Opposition Leader Chris Minns started his morning in Bega.

Prime Minister Scott Morrison gave a shout out to "dear friend" Bridget Sakr vying to win for the Liberals in Strathfield, as federal Labor leader Anthony Albanese lent a hand in pitching for votes on the ground in the same electorate.

Former deputy premier John Barilaro was also out spruiking for the Nationals candidate he backed to replace him in Monaro.

However a notable absence on polling day was Ms Berejiklian.

Liberal candidate Tim James is tipped to be her successor as member for Willoughby, a safe blue-ribbon seat on Sydney's north shore.

It's another story in Bega, where Labor is hoping it can net a "historic win".

The seat on the state's south coast was held by Liberal and former transport minister Andrew Constance on 6.9 per cent margin.

Labor has never won it but is hopeful local gynaecologist and obstetrician Michael Holland can break the drought.

Mr Minns painted the battle in the electorate as a referendum on the new premier.

"If a conservative candidate is re-elected in this seat, and in the seat of Strathfield, it'll give a green light to all of the policies of Dominic Perrottet," he said.

"Voters recognise that you can't change the government in a by-election but you can send a message.

"I think many people want to put a handbrake on the government."

However he was quick to clarify the by-election results were not necessarily a reflection on his leadership ahead of the general election in March 2023.

Dr Holland - who said his success would be a "historic win" - is running against farmer and former teacher Fiona Kotvojs for the Liberals.

But the Liberals are also threatening a Labor seat, won on a margin of five per cent at the last election.

Liberal candidate Ms Sakr - whose 11-year-old daughter died along with three other children when they were hit by a drunk and drugged driver at Oatlands in 2020 - is hopeful she'll be next member for Strathfield.

Upset over the departure of former Labor leader Jodi McKay, who many feel was treated unfairly by the party, could help carry her over the line.

Former United Nations lawyer Jason Yat-sen Li hopes to retain the seat for the Labor, with former prime minister Kevin Rudd previously lending his weight to his campaign.

Elsewhere, Nationals candidate Nichole Overall and Labor's pick Bryce Wilson are facing off in Monaro - held by the Nationals on a margin of 11.6 per cent.

The contests are the first electoral test for Mr Perrottet and Mr Minns.

Both were recently elevated to their position and both are painting their parties as the underdogs.

For Mr Perrottet, there is the usual swing against the government in by-elections, the loss of popular and senior MPs, as well as scrutiny of his handling of the surging Omicron wave.

The government is already in minority, and a loss of any further seats would force it to rely more heavily on the votes of independent or minor party MPs.

The stakes are also high for Mr Minns, who has pitched himself as the man to make Labor a real election chance after more than a decade in opposition.

Although some results will filter through on Saturday night, the NSW electoral commissioner says it could be a month before final outcomes are known, thanks to the high postal vote.

© AAP 2022