"Mais pourquoi y a-t-il toutes ces mouches ici ?"

Translation: But why are there all these flies here?

[gbarge]

there + here= bad sentence

[CinnamonTe1]

"But why are all these flies here?"

It's not the most literal translation, but it's certainly more natural.

[milas_h]

Can someone explain "y a-t-il" part? :)

[GraemeSarg]

It is "il y a" inverted.

When an inversion results in a vowel followed by another vowel a "-t-" separator is inserted. So "y a-il" becomes "y a-t-il".

[NimrodKapon]

Why do we have the y in this sentence?

[Andre872035]

Maybe this can help:
consider first making a statement and then ask a question:
- Il y a beaucoup de mouches ici.
- Mais pourquoi y a-t-il toutes ces mouces ici?

[NimrodKapon]

Thank you, it makes sense now!