I had a ant problem in mine a few years ago and used sevin. I have also used a graular insectiside around them but don,t remember the name.

Your iris got too wet and rotted, now the maggots are there eating the rotted part. I would dig them up cut off the rotted part and soak them in bleach water. 1 parts bleach to 9 parts water. You might want to build a raised bed for them to keep this from happen in the future. I would put in a drainage pipe under it too. I had a gopher run wild in one of my iris beds this winter. It ate a lot of them and others he just tunnel under them and killed them. I was sick for 4 months this winter or I might have stopped it sooner. Right now I am going through digging some that are barely hanging on and putting them in pots until I can wire the whole area. You might want to pot some of your up until you can find a dry spot for them. Here in California I put them in a place that gets morning sun and afternoon shade. If they look like they have recovered enough I will replant them in October after I have wire the spot. If they still look bad I just leave them in the pot until next year.

Whew I like the idea that they just got too wet. We live in a hot dry area and most of mine came through just fine. These are on a slope and the soil there is too much clay. And I made the mistake of mulching them with bark. Guess was loving them to death. I also put in a drip system last summer so they could have lots of water. Guess I will change my ways. Had planned on moving them from there anyway so I will dig and clean and bleach and think I will do the comet thing just in case. Thanks for the great info. What you said sure makes sense.