The latest info from our local bee-keeping Assc., says that the "merit" DOES show up in bee colony checks, as do several of the systemic fungicides, so it's concluded that it both are present in the nectar, and/or pollen. But, they felt the worst problem is "contact" with the product on the leaves of plants. So, I read this as saying ,treat the soil, without getting the product on the foliage. The Bayer product that I use is a liquid, and I drench the soil, trying to "miss" the leaves. In the past, I have treated in early spring shortly after new growth starts, and then re-treat when the bloom is done( Been doing this for 5-6 years, and have never seen any otherwise un-explainable problem with our hives), but next year, just to be sure, my plan is to start a "drench" program, in early season, with BT(thuricide).to try to catch the borer while he's still in the ground, and make him sick with a fatal disease( google thuricide for info). Then ,when bloom is over, make my usual application of my "merit" systemic insecticide,(to the ground around the plants). I think it can be timed to catch enough growth in the iris to put the insecticide into the plant, before summer dormancy starts. Something else to consider is that any of the powdered insecticides are really bad for bees, as the powder grains are either gathered with the pollen, or attach themselves to the bees legs, and gets carried back to the hive. Insecticide kills bugs, bees are bugs, so you have to use it both sparingly, and in a way to minimize the chance of affecting the "good" bugs. Nematodes have been used by some, and will control borers, but the only chance is to catch the borer between coming out of his pupa stage, and when he crawls up the leaf. And the Nematodes seem awful expensive to me. You have to be pro-active with any chemical borer control, as once they show up, it's kinda' late to do anything but squish them and treat the damage....Arlyn
