If you've been outside lately, chances are you've seen them — small flying insects that resemble sweat bees. In fact, you may have actually called them sweat bees. But in reality, you're most likely encountering hover flies.
"A hover fly is a kind of true fly that has only one pair of wings. They can be bee mimics, which is the reason why everybody confuses them with bees and little wasps and things," explains Kristie Reddick, entomologist and half of the duo who make up The Bug Chicks, a Cincinnati-based insect education team. "A lot of them are stripey, but they have these big, big eyes that look very different from bees, and they have short, tiny, little antennae, where bees have longer antennae."
Another big difference is that they don't have stingers, she says, so they're not going to sting you.
However, they may land on you seeking a salty treat.
"They might land on you, and they might use their sort of sponging mouth parts to kind of sponge at you a little bit. And I think people don't love that, but that's what they're doing. They're trying to get salt off of your body," she explains.
Hover flies drink a lot of nectar, which is sweet and liquid. Afterward, like humans, Reddick says, the insects want to follow with something salty.
"We come outside and our skin is sweaty and we're like a giant walking potato chip. And so they'll land on us, and they'll dab their little tongues on us, and they get a little lick, and they're balancing their electrolytes in the same way that we do with salty electrolyte drinks."
Sweat bee or hover fly?
Generally speaking, the sweat bees found around the Tri-State are slightly larger than our local hover flies, though not always, Reddick explains.
"There's like 400 species of hover fly in the Northeast, and maybe more than 80 [locally] because they're kind of under-studied. There's tons of hover flies in Ohio, but sweat bees — the ones that you're going to see right now alongside the hover flies — there's a metallic one with a stripy back to it; there's a metallic green one, and there's a larger one that's a little bit black and brown," she says.
Sweat bees do have stingers, though Reddick says they're generally not prone to stinging people unless you're messing with them.
"They fly very differently, and this is really what's going to help you to identify what's a sweat bee and what's a hover fly."
As the name implies, hover flies hover, similar to a hummingbird or dragonfly that can look suspended in air. Sweat bees — which are actually a type of bee — are more acrobatic and constantly in motion and swirling around.
Are there more hover flies this year?
A quick hunt around the internet suggests there probably aren't any more hover flies out this year than in the past, it's probably just you noticing them more. It's what inspired this news story, and Reddick tells WVXU she was just wondering the same thing the other day.
"Every year, in August, it seems that people in Cincinnati talk about how many hover flies there are," she says. "I think we notice them now because we're spending as much time as we can outside. In July, it was quite wet, and now it's like the perfect confluence of that heat and the humidity [that insects like] and the late summer nights, where they're out and they're getting as much food as they can, and we're out and we're soaking up summer as much as we can. And I think that's just what happens in August. You sort of see them more because we're all occupying the same space."
Winton Ray, curator of Ectotherms at the Cincinnati Zoo & Botanical Garden, seems to agree with that assessment.
In a statement to WVXU, Ray writes:
"I haven't noticed a significant increase in hover flies compared to previous summers, but insect populations naturally fluctuate from year to year and can vary quite a bit from one neighborhood to another. People's outdoor activity levels also tend to change from season to season, which can make personal observations of insect abundance quite subjective. Given these factors, it can be difficult to make objective judgments about overall insect populations.
"That said, I feel like I've seen fairly healthy numbers of many local insects this year. Some species were slow to appear — likely due to the unusually cold winter and the cool, wet spring — but overall, their presence seems reasonably strong."
Okay, but I'd still prefer they not see me as a potato chip
Again, hover flies don't sting or bite — they just might land on you and lick up some of your salty sweat. That said, if you'd prefer not to be an insect salt lick, you can try using a fan to keep the air moving around you while you're outside.
As for things like bug spray and citronella, hover flies don't seem to bothered much by those. Sorry!
Fine, but are hover flies important?
In short, Reddick says, yes.
"They're incredible pollinators as adults, but then as larvae, they're also important because some of the larvae are eating aphids and other pest insects, and some of the larvae are eating pollen, and so they're also helping to pollinate."
On the upside, they aren't destructive larvae. For example, butterflies are great and are great pollinators, but in the larval state they can be destructive to plants — you know, like butterflies are pollinators, but a lot of the larvae are destructive to plants.
She says with hover flies, we get the best of both worlds.
"You get these adult pollinators that don't sting, and you get these larvae — and yes, they're maggots because they're flies — but you get these maggots who are helping to knock down pest populations, and they're doing a little bit of pollination and eating some rotting detritus.
"They're just great," she concludes. "They're great all the way around."
