U also want to put soap in w the vinegar. The vinegar is what attracts them and the soap kills them. U can also find ready made in stores they look like little apples. Or take a bucket ant put a wet washcloth in it,it will attract the flies then put the lid on and let them go outside. This mite have to b done a few times tho. Good luck!

put vinegar in a glass and cover with cling film and pierce the film so there is a small hole. place this in the cage, the flies will be attracted to the vinegar, they cannot get out & will be trapped.

look on you tube - there are several methods

Get out the vacuum or shop vac and have at it.

I left my guinea pigs with family while I went out of town and their cages weren't cleaned the whole time I was gone. Now theirs a wall of small flies by their cages. I want to know how to kill them all with using bug spray.