Little blackflies

Those clever bugs have come and gone. Here's what we missed.

Sherry McPhail

5/27/20241 min read

a surprisingly colourful blackfly in close-up, with yellow, green and brown on a white surface
a surprisingly colourful blackfly in close-up, with yellow, green and brown on a white surface

Photo of Simulium trifasciatum licensed under CC BY 2.0, is by AJC1 on Flickr, who conjures image magic from the tiniest bugs.

Most people think of May and June in Ontario and Quebec as the bug season, and they would not be wrong. The much-maligned blackfly has already had its brief moment on the stage, and it’s always a huge success… for the flies. Luckily for us mammals, the run is short, usually only a few weeks in mid to late May. Here are some interesting facts you may ponder if you’re swarmed... next year.

  • Unlike mosquitoes and wasps that sting, blackflies chomp a tiny bit of mammal skin with their jaws and lap up the blood. They inject a numbing agent so you can’t feel the bite, and an anticoagulant so your blood doesn’t clot too quickly: clever.

  • That blackfly biting you is female and using your blood to grow her eggs, which she’ll lay in a calm, quiet spot. Just kidding: she lays them in a creek!

  • But the larvae know what to do when they hatch. They anchor themselves to…anything! by spinning sticky silk pads from their mouths and attaching the hooks on their butts to the silk pad. They can even ““walk” from silk pad to silk pad. Go ahead, watch the video! So talented, so young!

  • Larvae grab food to eat with their elegant “mouth brushes.”

  • Blackflies can’t tolerate pollution, so if you’re tormented by clouds of them, celebrate! It means our streams are clean.

To outsmart these tricky and talented tiny beasts, wear light colours, long sleeves, and pants. You might even don a bug-net hat. Or put on the repellent of your choice and enjoy your day on the trails as you look for spring flowers.

Also, enjoy this important Canadian cultural collab: folksinger Wade Hemsworth, musicians Kate and Anna McGarrigle, and NFB director Christopher Hinton created this masterpiece in 1991.