Those "bud bumps" (aka enations) are very common but the cause has never been proven. Years ago an author, I forget the name and would have to look it up, attributed it to aphids but it cannot be aphids as the bumps happen where there are no aphids on daylilies in a garden.
Usually these days the bumps are attributed to thrips but, as I say, that's not been proven. Another possible suspect I see here is the tarnished plant bug, or it may be something else entirely that we haven't thought of. I don't think anyone has suspected any cause other than a pest of some kind, though. I keep meaning to try some exclusion method, like mesh bags, to try and narrow down the possibilities but never seem to remember in time - it would have to be put on a cultivar known to typically get the bumps, and very early in the development of the scape plus be very tight around the stem. I think the majority of daylilies in my garden have the bumps, will try and check that later when the thunderstorms have finished. Other than curiosity as to the cause, I don't worry about them.
