I do think it is quite early for borers to have gotten fat even with the unseasonably warm weather. I have seen borers in the flowers at times but not this early. I do not know how they get there but it happens. I have spent the day dousing all of my irises with various sorts of chemicals to see which one works best. I have used 2-in-1 and All in One and Fertilome Tree and Shrub Drench as well as the Bayer Season Long granules. Mostly Merit only lasts about a month so must reapply. I do not know if that applies to Season Long Grub Control. And I have NEVER seen a borer egg. I think they are extremely small.
Moths can still lay their eggs in the fall and can wander over from other yards to land in yours. Sad but true.
