I think many growers have it and may not even know due to the high number of DL's they grow. Just go to the "July blooms" or "seedlings for July" threads and click on any pic with the foliage included and chances are you'll see it. I'm not going to say any names because some may take it the wrong way and I'm not trying to offend just help. It seems July , August, and September is when they appear in the highest populations according to a pdf I read last night but now can't find the link. I've noticed that tets seem to be affected more than dips in my garden not sure if there is a connection or just by chance it happened like that. The key here is it won't kill the plant but just makes it unsightly. They typically start near the tip of the foliage and move to the base so removing the the infected areas as they appear seems like a much better option than what I did. However like Sue said ditch daylilies are also a host of this pest so irradiation is virtually impossible. They are spreading like wildfire across the US so check your foliage often this time of year and you won't have to remove as much foliage as I did
I was told by many gardeners that daylilies are not bothered by pests or diseases but the deeper I get into daylilies the more I find this not to be true at all. I guess if you grow daylilies there are just some things you are going to have to deal with Leafminers are just one of the many. The lesson we should take away from this if any is don't acquire plants from overseas, there is a reason it's illegal and it's to stop importation of invasive species. The last thing we need in the US is more problems from other countries. I'm already dealing with Asian tiger misquotes, brown marmorated stink bugs, Japanese Beetles, Fire ants, Chinese privet, Japanese Honeysuckle, Elaeagnus umbellata, and now Daylily Leafminers.
