Really few species of flies in the Swedish waters! Few Ephemera, many types of Sedge and Terrestrial with particular refer to Ants and Bees.
At the beginning of the fishing season (June), related to the water levels, you would be looking at impressive May Fly hatches but take note that fish prefer the its emerger status.
Sedge from the beginning and later Terrestrial will be the best from July to the end of August.
Specific Emergers are great anytime during the all season. September when and where is possible to fish little dries will be the best.
In many years of fishing in Sweden we have conducted several tests with many and differet skilled fishermen, using samples of any type and special ones, so we could have made a proper selection for you.