Update on Hemerocallis Gall Midge

It has been some time since I have had a chance to catchup, but thought I would post an up-to-date memo since spring is 'supposed' to be here (mixed rain and snow again here today) and soon the gall midge will be flying.
Last year saw a definite decrease of the midge in our gardens, mostly due in part to our constant surveying of the plants and picking off anything that looks mildly suspicious! The main question I am asked is about chemical solutions to the problem. Since general chemicals will most likely be off our shelves in the next few years, gardeners have to find other ways of controlling insects and diseases. The gall midge is no exception. We do not use chemical pesticides on our property - not to say that we don't get aphids, etc., but simply because we do not like them and since we work with the plants and the soil on a daily basis just don't want to be touching anything remotely poisonous! Yes, you can certainly try a soil drench of insecticide to try to destroy the overwintering larvae - but at what cost? There are so many beneficial organisms to consider, like earthworms, who would also be affected. As for spraying the actual daylilies in the spring with a systemic insecticide, you would have to time it exactly so that you sprayed at a time when the larvae were feeding on the inside of the bud - but that first feeding would still cause the eventual flower to be deformed.
To that end, I have done a lot of research with the people in Europe, where the gall midge first came from. For years, we have been recommending the use of 'trap plants' - those are early blooming daylilies that the gall midge seem to enjoy the most (just as certain of my hostas seem to be cheesecake for slugs!) By planting a selection of certain trap plants around the garden, the midge fly to them almost immediately, laying their eggs and thus leaving other daylily plantings alone. This worked very well for us for the past three years, and I have sacrificed by beautiful plant of Hemerocallis Wynnson to the cause! Wynnson has been one of the very best trap plants - completely covered in gall midge damage at the beginning of June with absolutely no other plants around her touched! When I see the swollen buds, I just snipped them all off and destroyed them - almost every bud was damaged but it was worth it to see all the other plants around her bloom to perfection!
With our cold weather this spring, we don't know exactly when to predict the gall midge will be emerging from the ground. Over the past few years, highest flight time has been from May 1 to May 15th. The midge generally lives only 72 hours and it takes about two to three weeks after she has laid her eggs to see the larvae begin to feed, so keep a close eye on the plants especially from the end of May on. The main damage we saw last year was the first and second weeks in June - with the problem completely gone by main bloom time in July.
If anyone has any questions, again please feel free to email me at pamela1@istar.ca or call our office line at 604-856-5758 and I will be happy to help.

 

Thanks for the update Pam :)