Groceries stowed, kids in bed, you take a moment on the deck to enjoy a spectacular sunset. But…nearby, a female mosquito has detected your breath. And she’s not the only one. The bloodthirsty gang follows your carbon dioxide emissions to their source, forcing you to retreat inside with several itchy puncture wounds. We may go to the cottage to seek out wildlife, but while we’re there, some wildlife seeks us out. All of us have been victims of mosquitoes, blackflies, biting midges, stable flies, deer flies, or horseflies—the well-named “biting flies”—and perhaps even those bloodsucking hitchhikers, ticks. To arm you for battle: the dope on the bugs we love to hate.
A closer look: Blackflies are compact, less than half the length of most mosquitoes, and have a hump-backed profile.
Action time: They usually emerge in midspring and last through June. Main biting times are early in the morning and late in the afternoon, peaking towards sunset.
Avoid the bite: DEET repellents work but won’t keep them from swarming around your head. A screened bug hat is ideal (any hat helps). A steady breeze, even a slight one, deters these poor flyers.
Amazing fact: Numbers of blackfly larvae in streams can be staggering, up to 100,000 per square metre at lake outlets.
A closer look: If you are bitten by what seems to be a housefly, likely at the ankles, you’ve met a stable fly. To kill one of these frustrating masters of agility, you have to swat hard enough to hurt yourself.
Action time: Stable flies peak during the warmest part of summer. They like the bright light and heat of midday.
Avoid the bite: These pests are only somewhat deterred by DEET repellents. Covering bare feet and legs helps, though these biters can pierce thin clothing. They breed in manure piles on farms, but also along beaches in wet, rotting vegetation.
Amazing fact: They are blamed for nearly $1 billion in overall annual economic loss to North American livestock producers; a density of one fly per cow can drop milk output.
Deer flies and horseflies
A closer look: If a fly bites you, and you say “Ouch!” loud enough to be heard across a small lake, chances are it’s a deer fly or a horsefly. Deer flies are just larger than houseflies and have patterned wings. Horseflies are bigger, up to three centimetres long, and they usually have clear or uniformly coloured wings. After a swatting victory, it’s worth looking into your hunter’s beautiful eyes. Deer fly eyes are often iridescent red and green, while horsefly eyes may be striped with bright green.
Action time: Early summer is peak time, and the majority of species are most active a few hours after sunrise and before sunset.
Avoid the bite: DEET repellents give minimal protection. Since deer flies often bite the head area, wear a hat and cover your neck. Fortunately, they won’t bite inside a tent ora building. Unfortunately, both deer flies and horseflies have a particular love for windsurfers and swimmers.
Amazing fact: The huge compound eyes of a horsefly may contain 10,000 photoreceptor units, or simple eyes, which gives them superior vision.
A close look: Mosquitoes are delicate, with a long, slender abdomen and tube-like mouthparts for sipping nectar or, if they are female, blood. Our first alert may be a whining, dentist’s-drill-like sound, made by the wings of both sexes, beating from 300 to 800 times per second. Males are drawn in by the sound as they search for a mate.
Action time: They are out from mid-spring to autumn frost, peaking in late spring; most are active around dawn and dusk.
Avoid the bite: DEET-based repellents work; citronella-containing liquids work for short periods. A steady breeze (more than 15 km/h) keeps them away, so fans do help. Reducing non-natural breeding habitat around the cottage is wise, especially to avoid West Nile virus; flip pails and other containers so they don’t collect rainwater, and clear plugged eavestroughs.
Amazing fact: Malaria transmission makes mosquitoes, after humans, the most dangerous animals on earth, killing about 600,000 people a year. A temperate type of malaria once existed in Canada, mostly in southern Ontario and Quebec. With window glass and screens, the use of quinine, and the draining of marshes (prime habitat for the mosquito genus that carries malaria—Anopheles) for agriculture, malaria was eliminated from most of North America around 1900. Now, our only cases are travellers returning from hot zones, but transmitting mosquitoes still exist in Canada, so outbreaks could occur again.
Dan Schneider has taught outdoor environmental education for more than 30 years.
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