When one thinks of biting flies, the first thing that usually comes to mind is horse flies. However, there are a number of different families of blood-sucking flies, and, in fact, around one million species of 'obligate blood-feeders' can be found worldwide.
This is according to Dr. James Tansey, the Provincial Insect and Vertebrate Pest Management Specialist for the Saskatchewan Ministry of Agriculture.
It all seems to begin each summer with the tiniest of biting flies, the Ceratopogonidae, known as biting midges, or 'no-see-ems'. They're no bigger than two millimetres, and most don't even notice them until they've already felt the bite.
Tansey said, "They tend to have long antennae, whereas black flies have short antennae. Black flies can be really problematic as well, and of course, black fly feeding can result in some swelling and discomfort associated with the bite site as well, as can no-see-em bites, but both are obligate blood feeders, both problematic."
While black flies aren't as common here in the southeast, the saliva from these creatures' bites, he said, can cause strong reactions in people.
"In the case of black flies, of course, they're going to introduce an anticoagulant with the feeding site. This can spur continued bloodletting so that the animal can continue feeding," he explained. "There should be a numbing agent associated with the biting as well. And oftentimes you won't feel that bite until it's well underway, and of course, that's to the benefit of the biting fly, so they can get a blood meal and get out of dodge before they get smacked."
"All flies that are black are not black flies, all black flies are not all flies that are black," he pointed out.
Tansey said black flies are also known as 'buffalo gnats', "and the reason being is you get a close look at these things and their pronotum (that shield right behind the head) can have a bit of a hump shape to it, and the scales on the body of these animals can make them look bit fuzzy and a bit grey."
Another family of biting flies is face flies.
"You'll see these in close association with livestock, and these can be a real problem as well. They are biting flies, both the males and the females are blood-feeders, a close association with cattle and horses. They're about half the size of a house fly and look very much like a house fly, but they are blood-feeders."
Another one that's really common is the biting stable fly.
"This one is also associated, as the name might imply, with livestock," Tansey stated. "So the larvae are actually in the complete development inside the cow plops or the horse plops. So they'll use that as a resource. The adults are obligate blood feeders, so they're going to be feeding on the horses or the cattle, or you."
He said the stable flies are about the size of a house fly, and superficially, they look a lot like a house fly.
"If you get a close look at them, though, a lot of them tend to have a bit of a grey pallor to them. You'll see that coupled with, obviously the biting sensation," he said. "They really like my calves in particular, so to have shorts around stable flies is a bit of a recipe for inviting blood feeding."
He said the province also has a fair amount of horse flies, and deer flies, which are in the Tabanas family.
"So when we're talking about horse flies, they're obviously very large animals, excellent flyers, very mobile, great vision. They tend to feed at multiple sites, so they'll give you a couple of tastes before they actually draw a blood meal and can be a real nuisance because of that," he explained.
He said deer flies will engage in the same sort of behaviour, but, "their mandibles are actually sabre-like, and they'll actually stick these blades functionally into skin, and then you'll get lateral movement of these."
"So they open a pretty good-sized wound and then they'll lap up the blood that comes from that. So they're messy feeders, and they tend to get blood all over their faces when they feed and tend to draw a fair bit of blood. But they also have these pain-suppressing compounds in their saliva, to reduce the response from their victims. So they can be problematic."
A good way to tell deer flies from horse flies is deer flies tend to have patterns on their wings.
"Some of these patterns can be quite dramatic, in addition to having sometimes iridescent eyes and brightly colored eyes."
He said he has also encountered snipe flies in forested regions, however, not much is known about their biology as they aren't a threat to livestock producers. They do bit, though.
"The ones that I've encountered tend to be about the size of a house fly, with orange colour and can be voracious blood-feeders as well," he noted.
"I don't know that there's a broad appreciation for just how many fly species there are," he added, saying that all flies are in the order of Diptera, with biting flies, fruit flies, mosquitoes, and gnats and a number of different other groups included. He said there are about 125,000 species described worldwide, "with some estimates of roughly a million species worldwide."
He said the majority of those are still to be discovered.
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