I have found such bugs on top of areas that have soft rot (mushy stinky stuff) left after the borers have done their damage. The little bugs are eating the mush of the iris. It is probably too early for borers to have gotten big enough to see but if you had them before, the rot may be coming from the previous damage. Just a thought....I am no expert.
I also thought that beneficial nematodes were an non-chemical way to eradicate borers.
