Why do flies always try to land themselves in your face in the summer?

[james_pain]

What do they gain from doing this? Sounds like a pretty risky manoeuvre...

 

Does anyone know?Is there something in our faces which they eat/consume as food?

 

What evolutionary advantage does this action/behaviour provide to the flies?

Edited November 24, 2016 by james_pain

[Endy0816]

Sweat has water. Different hygiene products are scented as well.

[rangerx]

Flies are attracted to Co2.

[StringJunky]

Flies are attracted to Co2.

Yes, shouting and waving your arms is the best way to keep the little critters swarming around you because it increases the size and concentration of CO₂ you mix in the air around you.

Edited November 25, 2016 by StringJunky

[Itoero]

I think flies eat the dead skin, salt and oil.

So flies help to keep you clean

[DrP]

I think flies eat the dead skin, salt and oil.

So flies help to keep you clean

 

Yea - but they do this by puking all over your face first to pre-digest said skin, salt and oil, lol.

[CharonY]

Flies are attracted to Co2.

 

Really? I was only aware that they have a negative taxis at least in fruit flies. Do you have a reference at hand?

[DrKrettin]

 

Really? I was only aware that they have a negative taxis at least in fruit flies. Do you have a reference at hand?

 

I've found this link to Scientific American where they state that fruit flies are repelled, but mosquitoes are attracted.

[CharonY]

That is pretty much my understanding, too.

[StringJunky]

 

.....Females of many black fly species, however, require the protein from a blood meal in order to form and lay eggs. When they are in a maternal mood, they sample the breezes for excess carbon dioxide, a sure sign of animal respiration. Following the trail of carbon dioxide and breath odors, they track down their intended victim.

http://curiousnature.info/A1-Blackfly.htm

[CharonY]

Black flies would make sense, as they lay eggs in animal hosts thanks for that. So it appears that most likely only flies that actually attack humans are going to be CO2 attracted, whereas other are likely to show aversion. Question is how it is the case for houseflies and others that lay eggs in decomposing substrate (as they ware also likely to emit CO2). (this lack of knowledge also betrays the fact that I am obviously not an outdoors biologist....).

Edited November 25, 2016 by CharonY

[StringJunky]

Black flies would make sense, as they lay eggs in animal hosts thanks for that. So it appears that most likely only flies that actually attack humans are going to be CO2 attracted, whereas other are likely to show aversion. Question is how it is the case for houseflies and others that lay eggs in decomposing substrate (as they ware also likely to emit CO2). (this lack of knowledge also betrays the fact that I am obviously not an outdoors biologist....).

Flies per se is a bit too general in hindsight. Possibly, could there be some other chemical cue needed with the carbon dioxide, in either case, to attract each type to their desired target, say gaseous sulphides, in the the case of flies that like rotting stuff?

[DrP]

I have read about the mozzie attraction to CO2 before. It still has to be more complicated. I used to go fishing with a mate of mine. He loved me going because all of the mozzies ate me and left him alone. lol... Some people attract them more than others.... maybe I just stink.

[DrKrettin]

My own personal experience is that flies are mainly attracted to moisture. Where I live (Tenerife) the climate is very dry, usually a very low humidity. When I have had a shower and emerge with my head wet, I am tormented by any flies in the house who find it an instant target, and I usually finish up with the absurd attempt at swatting myself on the head for 20 minutes. When I've dried off, they lose interest.

 

They also make a beeline (if I'm allowed to mix insects) for any pools of water, such as in the sink or on a work surface where something has dripped.

Edited November 25, 2016 by DrKrettin

[CharonY]

Flies per se is a bit too general in hindsight. Possibly, could there be some other chemical cue needed with the carbon dioxide, in either case, to attract each type to their desired target, say gaseous sulphides, in the the case of flies that like rotting stuff?

 

I have read about the mozzie attraction to CO2 before. It still has to be more complicated. I used to go fishing with a mate of mine. He loved me going because all of the mozzies ate me and left him alone. lol... Some people attract them more than others.... maybe I just stink.

 

There is at least one study that found that in addition to CO2 black flies use other cues (Schofield & Sutcliffe) J Med Entomol 1996, though it was not clear which part of the breath could be involved. No idea whether there is something newer around.The only other thing that I remember is that pattern also played a role (striped and spotted were less attractive).

[arc]

Back when I was a kid we had some ponies and later a horse, the flies would always go for the animals eyes, nose and mouth looking for any moisture they could find.

 

 

 

http://insects.about.com/od/HouseholdPests/f/Do-Flies-Really-Vomit-And-Poop-When-They-Land-On-You.htm

By Debbie Hadley

Insects Expert

 

. . . . "Unfortunately for the house fly, it is not equipped to chew solid foods. Most insects that feed on solid food – beetles, for example – have chewing mouthparts, with which they can properly masticate their meals into tiny, digestible bits. House flies were instead blessed with sponge-like tongues. Only in flies, we call their tongues labella (the singular is labellum, but the fly has a matched pair)."

 

"House flies "taste" with their feet . . . . . When a house fly comes upon something that seems like it might be yummy (keep in mind that dog poop is the kind of thing house flies find yummy), it will reflexively stick out its labella and press it against the potential food item to investigate. Liquids can be slurped up without much effort. Inside the house fly's head is a structure called a cibarial pump (or food pump), which generates a suction to draw the liquid up through channels in the mouthparts (called pseudotrachea).

So how does the house fly make a meal out of meat, or any other solid food (like dog poop)? It uses those same mouthparts to liquefy the entrée."

 

"The house fly dabs the tasty morsel with digestive enzymes by bringing up a little regurgitated food and saliva. The enzymes begin breaking down the solid food, gradually turning it into a slurry the house fly can then lap up. Meat milkshake, anyone?"

 

"Now, think about the last time you had a stomach flu. Anytime you vomit repeatedly, you run the risk of dehydration, so you have to drink a lot of fluids to replace the ones you lost. Flies are no different. This liquid diet means flies require a lot of water. And when you drink a lot of water…well, let's just say what goes in, must come out, right? So flies do a lot of defecating, too."

 

 

The CO2 is likely what allows the flies to locate the animals which then provide the needed moisture through their eyes, nose and mouth openings. With their hydration needs satisfied they can then dine, mate and then lay their eggs on the surrounding feces that these one-stop fly supply emporiums provide.

 

And when they cannot find a horse or elephant or lion they will settle for us.

 

[Elite Engineer]

I think flies eat the dead skin, salt and oil.

So flies help to keep you clean

I didn't bother to check on this thread yet, but flies also land on feces. So fly + poop + your face = no

[brucechamp]

Flies are attracted to warmth, sweat, and carbon dioxide, all of which are more prevalent near your face. In summer, these cues increase, drawing flies to land on you frequently.

[StringJunky]

14 hours ago, brucechamp said:

Flies are attracted to warmth, sweat, and carbon dioxide, all of which are more prevalent near your face. In summer, these cues increase, drawing flies to land on you frequently.

Yep, panting and frantically trying to swat that pesky mosquito just excites them more.

[Ken Fabian]

Lots of kinds of flies. It looks to me that the sorts attracted to people are initially triggered by sight, especially seeing movement, to approach. Scent, which may include sensing CO2 (?) when close enough seems to confirm that the target is worth it.

Scent seems crucial to finding suitable places to lay eggs or maggots - those aren't necessarily live and moving to attract attention, although some do lay eggs or maggots on live animals. The biting sorts don't appear to have faces as preferred location on an animal. The OP seems to be about the non-biting sorts that seem to target sweat and bodily secretions, which eyes, nose, mouth provide. Water, salt, oils and other edibles seem to all be attractants. Probably to different degrees for different kinds of flies.

Humans often wear clothes, so not everywhere will be accessible - the apparent preference for faces will be skewed by that - not unusual for bare backs to be popular with the non-biting sorts that seem to be after sweat, but some do preference eyes, nose, mouth. Exposed genitalia and anuses can be popular too. I note that faces, especially around eyes, nose, lips have high sensory sensitive, including via the small vellus hairs that enhance fine sensory sensitivity; flies seem especially able to trigger those urges to swipe or scratch or swat.

Whilst humans often get overwhelmed by them we are still far better fitted to do things about them than other animals - find or make a tool to swat them with, identify repellent plants and rub skin with them, mix ash and fats into repellents and pass on knowledge of what works. I expect our long ago ancestors also had fewer qualms about eating what they swat - big juicy biting flies are probably nutritious and I recall a doco about some of the best and worst of hippies, that had a 'free range' boy talking about things he did for having fun which included catching big "marchflies" - then eating them.

Edited September 12 by Ken Fabian

[John Cuthber]

It's often the biggest area of exposed skin.