how do flies understand where the (small) water sources are?

[ahmet]

hi, 

I was working  and I have almost always drunk water regularly in my room (I use an open tip cerafe for this but generally drink much water as doctors recommend) in the past for a long time I could not realise a detail but one day I was again drinking water, I directly tried to drink water from that cerafe and realised that something was moving over the surface of water.

I realised or still suppose so , that it was one of flies (larva). I presume they release their eggs,(spawning) (go) through inside of water. 

but I wonder how the mother flies could understand where my cerafe is?

how can they do that?

thanks.

Edited October 17, 2020 by ahmet
one missed word added: larva, one more convenient word change applied (release-allow), paranthesis used

[TimeFlies]

W.C. Fields(Amer.commic).."Water is for washing..Liquor is for drinking"

[joigus]

Ok. I have no idea what a cerafe is, but:

On 10/17/2020 at 4:12 PM, ahmet said:

I use an open tip cerafe for this

(My emphasis.)

The rest, I suppose, can be explained by the behavioural traits of flies.

[Area54]

On 10/17/2020 at 3:12 PM, ahmet said:

but I wonder how the mother flies could understand where my cerafe is?

Water evaporates. Water molecules drift through the air. Flies detect water molecules and move up the concentration gradient.

[zapatos]

Some flies find water by detecting humidity changes with a sensor on their antenna.