I know that this is an old thread but my experience may be of use/interest to posters with this problem.
I am in the UK and this is my second year dealing with this. Last year was awful with very many plants affected but as I was not experienced or knowledgeable about the pest I was maybe not as ruthless as necessary and any buds I wasn't sure about I left on as I was so worried about having no blooms left.
This year about 5 plants have been affected, so much better than last year,and I have been much more ruthless in removing and destroying any suspect buds.
I have been advised that the midge can travel up to 5km (yes, 5) in search of the host plant. HOWEVER, so far only plants in my back garden have been affected, the two in the front haven't been attacked (but I don't know if they would have been if the daylilies in the back hadn't been there!).
The RHS in Britain did trails with pesticides and found that they can considerably help with but not eradicate the problem, esp. one made by Bayers which reduced the incidence from 14% affected plants to 1% during the trial period. It is called Bayers Provado Ultimate Bug Killer.
I have read that you can destroy the buds and larvae inside by dropping the buds into bleach before sealing in plastic if you are not able to burn them but haven't tried this--not sure if the bleach needs to be dilute or concentrated!
Here in the UK it appears that different plants have been targeted than last year with mainly purple varieties being mainly affected this spring, not yellow as I usually read is the case (not ony in my garden but also confirmed by another daylily specialist).
Next year I am going to try and protect favourite varieties by putting organza or mosquito net bags over the emerging scapes and making necklaces of yellow sticky insect trap tape as an experiment.
Unfortunately I don't know how to do links but the RHS HEMEROCALLIS GALL MIDGE study can be found online and the results available as a download file for anyone interested.
Hope that helps someone!
