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As irritating as they may be, blackflies are only doing their job

In January, the Royal Canadian Geographic Society asked Canadians to join in on a contest to name Canada's national bird – something this country is said to be sadly lacking.

The debate began immediately: those beyond the city limits calling for the common loon, those within cities accepting it might have to be the all-too-common pigeon.

This being the end of May, it would be more timely, surely, to name Canada's national insect. And in this contest there is simply no contest.

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The blackfly.

There are more than 100 species of the creatures in Canada. They are in our eyes, our noses and deep inside our ears. They show up in our children's diapers and in our patio drinks. They are far more ubiquitous than the beaver, the moose or even Canada geese – so how can they not be a national symbol?

The blackfly has been celebrated in music – Wade Hemsworth singing "… always the blackfly, no matter where you go" – and it has been cursed since the first Europeans paddled off into the wild without Deep Woods Off.

"If I had not kept my face wrapped in cloth," Recollect missionary Joseph Le Caron observed 400 years ago, "I am almost sure they would have blinded me, so pestiferous and poisonous are the bites of these little demons. They make one look like a leper, hideous to behold. I confess this is the worst martyrdom I suffered in this country: hunger, thirst, weariness and fever are nothing to it. These little beasts not only persecute you all day but at night they get into your eyes and mouth, crawl under your clothes …"

It is said that, in China, flies were effectively eradicated by having more than a billion flyswatter-armed citizens march against them. Scientists have calculated that the blackfly population of Canada might be eliminated in the same fashion – but first our population would need to exceed a trillion and DDT would have to be taken off the banned list.

Real scientists have, in fact, considered in some depth the blackfly. Last Sept. 16-19, the sixth International Simuliidae Symposium was held in Turin, Italy. The gathering, organizers promised, "would embrace all areas of blackfly research." Leo Rivosecchi, a retired researcher with the Italian National Institute of Health, even presented a paper entitled "A Lifelong Passion for Blackflies."

Surely, this was an assembly that should have taken place in Canadian cottage country, for as organizer Simone Ciadamidaro conceded in an e-mail to The Globe and Mail this week: "In Italy blackflies are almost unknown by common people." In Canada, on the other hand, blackflies are the scourge of common people who can be found walking on any back road or path wearing hideous mesh outfits that are something between diving gear and astronaut suits.

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Canadian paddlers, campers and cottagers have long rationalized the blackfly's spring offensive as something necessary for the blueberry crop. It turns out, however, that this may have been wishful thinking by those who believe there could not possibly be true evil in this world.

In a scientific paper called "Shattering the folklore: black flies do not pollinate sweet lowbush blueberry," published by the Canadian Journal of Zoology, Brock University researchers Fiona Hunter, Steven Burgin and Allan Woodhouse set out to test this common belief.

While it is true that blackflies feed on nectar for energy to keep pestering and procreating, the researchers found that the blackflies did have some pollination effect on leatherleaf plants, often found near blueberry, but could not show the same for blueberry plants, even though blackflies were among the multiple feeders at blueberry blossoms.

Still, the researchers were left with the oft-repeated claim that blueberry yields are highest in years when blackflies are thickest. They could only speculate: Perhaps the scourge of blackflies depletes the nectar to a point where true pollinators, such as bees, are forced to visit more flowers to gather what they need.

Adam Brown, an entomologist at the University of Ottawa, has studied the pollination of cloudberry and blueberry, mostly in northern Quebec. Although he says "I have a great deal of experience cursing the blackfly," he is willing to defend the existence of the creatures most Canadians wish had never been created.

"They do have value in other ways," Prof. Brown says. "Just because of their sheer numbers, they are very important in the food chain of whatever ecosystem they inhabit."

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Blackflies lay eggs in fast-flowing water. Let the mosquito have the stagnant standing water and ponds – the blackfly likes the same clear, cool and swift-moving streams in which brook trout are found. The blackfly larva is a significant food source for trout and other fish, as well the larvae of such beneficial insects as dragonflies and damselflies.

The blackfly provides a direct link between the aquatic and terrestrial world, serving as an important food source when they are in the larval stage and again as adults: Fish and other aquatic creatures eat them in streams; birds and bats eat them when they emerge as adults.

In a delightful tracking of one food-specific chain, dragonflies feed on blackflies when dragonflies are still in the water, and again when both are adults and in the air. And dragonflies, bless them, also feed voraciously on mosquitoes.

"If you were to take a major player out of an ecosystem – and make no doubt about it, blackflies are a major player – then it can have a cascading effect on others inhabiting that ecosystem," Prof. Brown says. "They are one important piece of the puzzle."

And though no one has ever exactly solved the puzzle, the belief persists that more blackflies mean more blueberries.

Which bodes well, at the moment, for the coming summer.

"Nobody likes being bitten," says Prof. Brown. "But there is a silver lining."

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About the Author

Roy MacGregor was born in the small village of Whitney, Ont., in 1948. Before joining The Globe and Mail in 2002, he worked for the National Post, the Ottawa Citizen, Maclean's magazine (three separate times), the Toronto Star and The Canadian Magazine. More

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