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, 20205 yr by ahmet
one missed word added: larva, one more convenient word change applied (release-allow), paranthesis used

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

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.

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.

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