Should i give up???

[Murray of the Deep]

A quick google search suggests they can pick up bacteria from stuff they land on (like rotting meat), but I'd expect this isn't likely to be a problem unless you're wallowing in filth. This definitely shouldn't be an issue if you are culturing the flightless version, which is the only sane thing to do if you plan to use them as feeders, as they should come from a clean source and you control their diet and living environment.

The fruit flies you have are pests, so killing them off in the freezer would be a good idea anyway.

And also how can I trap those flightless fruitflies?I cannot buy them at any store in the Philippines!!!and also I can only find those flying ones(red,white,black) eyes.