Meanwhile, for us and our mostly gray, common housefly, this Black Flag brand of fly ribbon paper is one of the two best brands we tried and were happy with and we had tried several different brands at random. For some reason our area, we have an annual summer influx of filth flies and other bugs, so we have gained a lot of first hand experience dealing with flying summer pests.
We're in the U.S. Northeast so these types of flies are common here. As far as we can tell, this summer we have primarily the common housefly (Musca domestica). We also have had some other similarly sized flies that look almost the same, like similar dung flies and flesh flies, but we definitely have mostly the above common houseflies. So far, we don't have (and we usually do not have as much as the above), crane flies, fruit flies, drain flies, moth flies, soldier flies, gnats and mosquitos. We do not USUALLY get (if at all) especially biting flies (blood sucking flies): such as deer/horse flies, soldier flies, black flies, etc. that I know of.
My guess is that some of these fly ribbon paper products work because they have an smell attractant, or something on it that smells good to specific types of flies. Since the ones I have found successful have worked on common houseflies and related, my guess is that the ones I bought probably smell like these types of flies favorite foods: they like to eat organic waste products such as dung, rotting vegetables, carrion, or dead bugs. Some flies like sweet or sugary smells (especially fruit flies), or perhaps smell of fermentation (foods which ferment also usually emit a lot of carbon dioxide, which some flies also are attracted to). Or perhaps some type of fly pheromones to attract mate-seeking flies, though I don't know if such pheromones are species specific, or not.
My guess is in some areas, I wonder if people may have the other types of flies I do not have fortunately, notably the very annoying and even painful biting flies. I think these flies are seek out blood, or the smell of blood, such as in mammals (like cattle, farm animals, or people). If they bite mammals, they may also detect the smell or presence of carbon dioxide and warmth given off by mammals.
The Black Flag brand worked great at attracting this type of fly very quickly and we were glad to have tried it. But we actually like one other brand that was both cheaper (per roll) and surprisingly even more effective: Scented Bug & Fly Ribbon by Catchmaster. We bought the Catchmaster by a larger box (of 20) and it ws much cheaper, per roll. Not only did it seem to get about the same amount of flies (lots!), but it seems to me that it did it quicker as the flies seem a little bit more attracted to it, so the "scented" Catchmaster seems to help for sure. But I haven't yet found this brand of fly ribbon locally at retail, so if you really need to get something from the local store right away, I would definitely recommend Black Flag since it is almost as effective.
And a cleaning tip: fly ribbon tape has to be very sticky to work, but it means it is really difficult and annoying to remove if you get any on your hands and just simply soap and water barely helps at all. We learned a great tip online: use a couple of drops of plain kitchen cooking oil (or canned spray oil is perfect) and rub it into your sticky hands for about 5-10 seconds. You should feel the stickiness improve almost immediately. Then, just wash off the oil with regular soap and water before.