Sweat flies?

[Jim Ford]

I expect most of you have met these nuisances!

They don't bite but just buzz constantly round you. I usually try to ignore them, but after a while break down and grab a bunch of dry heather, and thrash around trying to kill them or drive them away. It never works but gives a modicum of grim satisfaction.

Insect repellent doesn't work because they don't land on you.

Are you bothered by them?

Jim

[Mungo]

I HATE THEM!

Went to Tring a couple of weeks back, the place was heaving with them.

[NickCantle]

They follow my other half, so I don't mind them

Having said that, I have to listen to her moaning about them, so for that reason I hate them.

[agrumpycow]

Have to say I don't have a problem with them
Sure, they follow me around but I don't really notice them!

[Kayleigh]

Ohhhhhhhh is that what they are.......
Dam annoying they do make your head itch though they follow you for a while then disappear ..

Why are they called that...Do they smell your sweat..

[foxy mars]

Well, so far, no flies on me at the moment. I was out walking yesterday in the Teesdale area and never saw a single fly, which is strange. That's what I like about cycling, the little blighter's can't keep up with you.

[balkantrek]

These flies have always intrigued me. Over the many years I have been guiding groups in the Bulgarian mountains I have noticed that certain members of my parties attract clouds of flies whilst others hardly have any....and this doesn't always correspond to those who are sweating most profusely.

And what is it exactly in the sweat that attracts these flies? There must be a certain mineral, element or protein that attracts.

I looked up the components of sweat on Wikipedia and read the following;

'Sweat contains mainly water. It also contains minerals, as well as lactate and urea. Mineral composition will vary with the individual, the acclimatisation to heat, exercise and sweating, the particular stress source (exercise, sauna, etc.), the duration of sweating, and the composition of minerals in the body. An indication of the minerals content is: sodium 0.9 gram/liter, potassium 0.2 gram/liter, calcium 0.015 gram/liter, magnesium 0.0013 gram/liter[4]. Also many other trace elements are excreted in sweat, again an indication of their concentration is (although measurements can vary fifteenfold): zinc (0.4 mg/l), copper (0.3 - 0.8 mg/l), iron (1 mg/l), chromium (0.1 mg/l), nickel (0.05 mg/l), lead (0.05 mg/l). [5] [6]. Probably many other less abundant trace minerals will leave the body through sweating with correspondingly lower concentrations.'

It was the mention of lactate that intrigued me....lactic acid (or milk acid)...because of course this is found in yoghurt and other sour milk products.

And I started to wonder whether this was actually the component in the sweat that was attracting the flies...

Bulgaria is the 'home' of yoghurt (Lactobacillus bulgaricus) and it is one of the staples of the Bulgarian diet....and so I have always thought it would be a very interesting experiment to see if people who ate the most yoghurt attracted the most flies! From my own, totally unscientific observations, there has always appeared to be some correlation!

Another interesting thing to ponder.....Presumably, and maybe someone with an entomological background can answer this, these sweat flies are the same species of fly one sees swarming around the heads of cows? But are the cows sweating? Or is there some other chemical being produced by the cows that are attracting the flies? And if so...are people who attract the most flies for some reason producing chemical attractants that are similar to those produced by the cows? And could people who eat more yoghurt or dairy products be producing more of this attractant because they have more 'cow chemicals' in their bodies!

Perhaps I should apply to a university and do a research degree on the subject!

[ron1863]

Those are the flies you rarely see, as they always seem to buzz around the back of your head

[Phoebe]

Well I must admit I did't know they were referred to as Sweat Flies

balkantrek you pose an interesting thought there

[sunnydale]

Originally Posted by foxy mars

That's what I like about cycling, the little blighter's can't keep up with you.

Maybe not....but they can still disappear up your nose or splat themselves in your eye while you're hurtling towards them!

It's the little titchy midges that annoy me on hot Summer evenings. They do love to have a nibble
I've been known to light an incense stick and carry it with me on evening walks!