We started using Aspects HummZinger brand which is a saucer type feeder with red flower ports. We rarely have wasps visit the feeder but the hummingbirds seem to use it with no problem.
After I read the response recommending the saucer-type hummingbird feeder, went to town & purchased a Perky Pet brand. Quite similar to recommended feeder, except the feeder ports have yellow flower covers, while recommended one was all red. Will say, that even with the yellow ports, have seen no more than 2 yellow jackets at a time on the feeder & only for a few seconds. Where the day previous, on inverted bottle type, had 8-10 at every port & 20-30 more hovering all around.
So, quite satisfied with the Perky Pet type. And, the Calliope & BC Hummingbirds have been feeding, unmolested by wasps, all day. Believe main benefit is simply switching to a saucer style feeder, once the yellow jackets & wasps swarm. Hope this helps, if getting invaded by wasp swarms.
Towards dusk, a juvenile Rufous male came in to the platform feeder last evening. During the height of a windstorm. Literally, took over the feeder, keeps ng all comers away, lol! First Rufous have seen since early Aug.