For most Australians, hating flies is something of a national sport.

Not associate Professor Wallman. He thinks the ancient creatures are not just underrated but beautiful.

Associate Professor Wallman, from the University of Wollongong's Faculty of Biological Sciences, features in a new documentary which screens on ABC TV on Tuesday, April 7.

This is not the first time Professor Wallman, as entertaining an entomologist as you will find, has featured on TV for his fly work. The previous occasions involved his work with forensic investigators, studying the development of maggots in a corpse, to help police discover how long the person had been dead.

Professor Wallman said English colonisation brought livestock, a massive increase in manure - and an explosion in the population of the bush fly.

"People have a love/hate relationship with the fly - much more hate than love," he said.

"The bush fly goes in your ears and up your nose. It's a small black one, we're familiar with it in Wollongong. Around November in particular it often blows in from the inland."

But the fly has been around since the time of the dinosaurs.

"The diversity of flies is enormous - there's over 7000 species that we know about in Australia, and there are likely to be four times that," Professor Wallman said.

"The importance of the species environmentally, other than the pest ones, cannot be overstated. If it weren't for flies and their role in nutrient cycling, their role in breaking down vegetation and breaking down dead animals so it can be recycled, the ecosystem, would come to a grinding halt.

"They have co-evolved, or evolved alongside, other animals and plants for millennia. Bees are familiar to many people as pollinators but flies actually do a better job in many ways because they're more active, they're just as hairy."

He won't even accept that they are a bit ugly.

"Most people don't take the trouble to look at them closely," he said. "Most flies, if you look at them under a microscope, are dazzling beautiful."

Few people share his passion for flies.

You lie on the couch to snatch 20 minutes of quiet. Then, circling, a fly makes its presence clear. It picks a spot on your shin to crawl around. It's just out of reach of your hands so you shake your leg.

The fly takes off, circles, returns to exactly the same spot. You shake again. It comes back.

The so-called Chinese water torture doesn't get you because of the regular dripping - it's when the gap between drips suddenly gets a little longer, and you let yourself think it has stopped.

Then another drip.

And the fly returns to the same spot. Why? Get a life!

Whether Professor Wallman's explanation is reassuring or disturbing is probably also in the eye of the beholder. The fly is eating your sweat.

"They can taste through their feet," he says.

"As soon as they land on you they can taste whether there's something there which can be good for them.

"What they get from us is nutrients that are secreted through our sweat. They need that nutrition ... the females in part need that nutrition to mature their eggs."

Professor Wallman has studied flies for more than 25 years after finding his calling during his third year of a science degree. Now he is focusing on the charmingly named small hairy maggot blowfly.

"It's bright green. It's actually quite pretty when you see it up close. But the maggot's quite bristly. [It's] very useful in forensic science, but it's also interesting because it has a very obvious courtship ritual. The male courts the female prior to sex.

"I've always been into creepy crawlies but I just didn't know until that point it was flies I was in love with. I knew it was something - not so much bizarre, but a bit idiosyncratic."

Professor Wallman credits flies with supremely advanced senses, just as sophisticated as humans. Perhaps this is why it's difficult to sneak up and whack them. The entomologist is more sympathetic.

"Like most creatures their whole purpose in life is to reproduce," he said. "So they need to stay alive long enough to do that. They need to find food, that's a priority, but they also need to reproduce.

"A lot of people think that flies and other insects are really base creatures, really primitive. But they're just as refined, and even more sophisticated in some ways, than we are, even if their behaviour may not be quite as intricate as human behaviour.

"Flies have their own personalities to an extent - and their sensitivity to the environment, particularly chemical sensitivity, sensitivity to the light and sound is incredibly subtle and beyond what we can appreciate."

It may appear there's touch of evangelism to the associate professor's delivery. And rightly so.

He is sharing his knowledge on an intricate subject many people may dismiss with the speed of a swat or a burst of spray.

"Although people like me that feature in the film might seem to be eccentric or rather unusual in terms of our interest, hopefully we'll get the message across that flies are worth thinking about differently than most people are used to."

The Great Australian Fly, ABC 1, Tuesday April 7, 8.30pm.