CHARLES BURY
Canada's champion biting insect is the small but painful black fly. A few years ago I had to go to a convention in Winnipeg and decided to drive. Most of the way, about a thousand miles, is along the Trans Canada highway, through the spruce-moose woods of the Laurentian shield.
The weather was good, the motoring was better, and I got to Manitoba a couple of days ahead of schedule. I decided not to stop, and ended up that night in northern Montana, where Louis Riel spent his exile after the troubles of 1870. I made it back to Winnipeg quicker than Riel did, but was still barely in time for the meeting. As soon as it was over I hit the road again, taking the northern route homeward - more or less - through Northern Ontario, Abitibi and central Quebec. This time I ended up at Lake Mistassini.
From there the route home was straight south - again more or less - through Chibougamau, Dolbeau. St-Félicien, Roberval, La Tuque and Three Rivers. This was a pleasant trip indeed but the thing I remember most was the flies.
Black flies. Simulidae. Millions of them. Billions. Per acre. It was early June and the flies were so thick they were driving the moose to distraction, forcing the big beasts up onto the roads where they could try at least to dodge the hordes. By the time I got home, the front of my truck was coated about half an inch deep with spattered insect parts, and the blood of ten thousand moose.
These critters are not nice. As the experts at Agriculture Canada put it, "in the forested parts of the Canadian Shield in June and July... members of the Simulium venustum species complex can be so numerous and can attack so persistently that outdoor activity during the day without some protection becomes almost impossible."
"Their numbers, and their tendency to bite, increase as sunset approaches. Even when they are not biting, however, their buzzing presence and constant crawling is as irritating as the bloodsucking itself. Mercifully, relief comes after dark, for unlike mosquitoes and biting midges, black flies do not attack at night."
So one way to avoid the black fly is to sleep all day and stay up all night. Another method of avoidance it to stay inside. Also unlike mosquitoes, "black flies seldom attack indoors or even in a vehicle; once they sense being trapped their attention seems permanently diverted to escape and they spend the rest of their lives crawling up the screen or window pane."
Wearing the right clothing can also help one avoid the bite. The woodland fashion statement: Cover your entire skin and wear light colours.
"Although they cannot bite through clothing, black flies have a predilection for crawling into hair or under clothing, biting in inaccessible places, such as the ankles and belt line. Tucking trouser cuffs into socks will normally prevent them from getting at the ankles."
"Black flies are strongly influenced by colour - they find dark hues more attractive than pale ones, and blue, purple, brown, and black more attractive than white or yellow.
A light-colored shirt, therefore, is a much better choice of clothing than a dark blue one. It is a moot point, however, whether blue jeans might not be better than pale trousers: if they are carefully tucked in at the ankles and are without holes, jeans may help to attract the flies away from the head region."
"In southern Canada, black flies are on the wing from early May (coincident with the bursting of buds of forest trees, especially sugar maple, before mosquitoes appear in numbers) until mid-June."
Although moose and people are their best-known victims, their favourite targets are actually birds.
"There are more species of black flies than of mosquitoes in Canada; over 100 have already been recorded, and there are more that have not even been named. Black flies are more selective in their choice of host than are mosquitoes, and comparatively few species take human blood. Most species seem to feed only on the blood of birds and a substantial percentage apparently do not take blood at all, because their mouthparts have degenerated and appear useless for bloodsucking."
And if you really want to be safe from bother in the woods, just hold your breath.
"Bird biters may... be attracted to man, probably by the carbon dioxide he breathes out, and when numerous can be annoying, even though they do not bite."
"Black fly larvae of various species may be found in every type of flowing water, from minute seepages in which the flow is scarcely detectable, to the largest rivers and waterfalls... Each larva normally remains fixed in one place, clinging by means of a ring of numerous minute hooklets at its posterior end to a small pad of 'silk,' a salivary secretion that the larva attaches to an object in the current."
Though their parents are more particular, baby black flies will eat just about anything they can get a hold of -- and this can be their downfall. This eat-anything habit reminds me of my True Love's dog. "Larvae cannot easily discriminate between different types of particles and swallow everything within a certain size range that gets caught by their mouthparts, including the fecal pellets of larvae upstream."
Scat-sucker. Ugh. Yup. One of the black fly's little-known abilities is to travel in the water like a spider does through air.
"After attaching a new pad of silk, the larva grasps it with the hooklets at the end of its anterior proleg (a finger-like projection just behind and below the head), releases its posterior hold and brings the posterior hooklets forward to grasp the new pad. A larva can thus progress, albeit slowly, in a looper-like fashion. If irritated, however, the larva instantly attaches some silk to the substrate, then lets go completely, drifting downstream at the end of a dragline of silk like a spider, except that the silk is produced from its tongue rather than from spinnerets as in a spider. It can then either work its way back up the dragline or drift downstream indefinitely until a suitable situation is encountered again."
The next stage of the black fly's life - the pupa - is similar to that of the caterpillar. "When a larva is fully grown, it searches out a suitable place to spin its cocoon, in which it pupates. The cocoon, a sac-like or slipper-shaped structure... is always firmly attached to some underwater object, or even partially buried in the bottom silt, with the anterior end of the pupa protruding from the opening. All black fly pupae have a pair of filamentous gill-like organs, arising behind the head, for gas exchange; the number and shape of these organs is of diagnostic value in identifying the species."
The black-fly pupa is self-inflating like the best balloons. "After a week, or more, just before the adult is ready to emerge, the pupa fills with gas. The adult emerges, expanding its wings as it does so, and, leaving the pupal skin behind in the cocoon, bobs to the surface completely surrounded by this protective film of gas."
Unlike many forest creatures we think of as tougher than a fly. But how many of them spend all winter shivering and growing under the ice to get a head start come spring? They winter in the larval stage, "often under the ice, where they slowly mature. They are thus ready to pupate as soon as breakup comes, and they are the first to appear as adults."
Maybe someone somewhere will discover what I already know - that the combination of moose blood and fly parts can be as tough as armour plate. I never did get my truck clean after that trip.
Surfers of the world unite. Learn more about Canada's insect world by tuning in to the Backyard Bug Brigade, at http://www.ns.ec.ge.ca/epb/factsheets/bkyard_bug/bugs_brch.html. Charlie Bury is a freelance writer based in Birchton, Quebec.
Copyright © 1999 Charles Bury/Log Cabin Chronicles/7.99 |
