You're not going to like why some flies are biting you right now - Cleveland 19 News Cleveland, OH

You're not going to like why some flies are biting you right now in Northeast Ohio

These are two species of horseflies that do bite. (Source: WOIO) These are two species of horseflies that do bite. (Source: WOIO)
This is a stable fly that does bite. Northeast Ohio has a huge stable fly population. You can tell them apart from a regular house fly by the black dots on the back. (Source: WOIO) This is a stable fly that does bite. Northeast Ohio has a huge stable fly population. You can tell them apart from a regular house fly by the black dots on the back. (Source: WOIO)
This is a common house fly that does not bite. Notice it has black stripes on its back not dots. (Source: WOIO) This is a common house fly that does not bite. Notice it has black stripes on its back not dots. (Source: WOIO)
CLEVELAND, OH (CNN) -

It's that time of year when you're sitting at a picnic and snap!

You look down and see a fly is biting you. 

But why do some flies bite and some don't?

"There are a lot of flies out there. There are 125,000 species world wide," according to Dr. Gavin Svenson Director of Research & Collections with the Cleveland Museum of Natural History. 

Most of those species don't bite. 

Svenson says most flies feed on liquids like animal droppings and fruits which means they don't have the mouth parts to bite.  

A fly that bites is looking for blood. 

"Tabinids, or horseflies will actuallysaw into your skin and create a wound and they'll actually drink up the wound as it bleeds," Svenson said.

Flies use the blood as protein to produce eggs. 

If you've ever been bitten by a fly in Northeast Ohio it was more than likely either a horsefly, deer fly or a stable fly. Yes, stable because they like to feed on stable animals. 

If you're thinking you've never bled because of a horsefly bite you're right. 

"No, it typically takes a little bit of time and most people are swatting these things away because they feel that initial sawing action," Svenson said. "But cattle on the other other hand they don't have hands and stuff like that so they have to stamp their legs, or horses stamp their legs and try to get them off of them."

Editor's note: This content is part of a partnership between Cleveland 19 News and the Cleveland Museum of Natural History. Find more videos like this on Cleveland 19’s Roku and Amazon Fire apps.

What’s crawling in your house? Prowling in your backyard? What am I seeing through my backyard telescope? Did I really just see a bald eagle during my drive home? Are coyotes dangerous? Experts from the Cleveland Museum of Natural History join us to set the record straight on Natural Cleveland – helping you better understand Northeast Ohio nature and providing tips on how to best share our region with our wild neighbors. Explore the wonders of science and nature at cmnh.org.

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