When a gopher had moved in that is what happened to mine! I scrambled and got all in that area potted. A critter is pretty desperate to eat beardeds' rhizomes.

Voles will do that in fall when they're fattening up for winter. Remove all mulch from around your iris and sprinkle Tabasco on the rhizomes.

Voles usually eat mine from underneath.. I would say that's an above ground critter.. Do you have lots of crickets in the area?? I let one of my beds go pretty bad, when digging them in July..many of them had cricket damage...

Don't chance it, just pot them for a few years to get them well established first with stronger root system. They will have a much better chance!

Does look similar to black lawn beetle larvae, because of the smaller holes?

Larvae looks like a big white hairless caterpillar curled up. Found if you dig deeper. Destroy in larvae stage with granular killer.