My experience with the iris bore began in about 2008 when we had an unusual amount of rain with flooding and roads washing out. That's what, in my mind, brought on the bore in my area of Wisconsin. Never even knew what they were before that. Unfortunately it took a couple years before I realize what they were and what they were doing to my iris patches.
Once I knew I did lots and lots of clean up in the gardens (not that I don't do that normally, but this time it was mega clean up). Also did a lot of research on the internet. I learned how to spot it early - always watch the center leaves as Tom said. If they are browning and look somewhat mushy - chances are you have a bore in there. When you do find them and get them out - burn the leaves, do not compost. After a couple years more I read about using lawn grub granules. My favorite is Bayer. I apply every spring around the time the temperature reaches 70. Do this without fail every year and you will get great results. One very interesting thing I found out from my research is that the bores practice cannibalism and will eat one another until there is just ONE left in each rhizome. So thankful for that!!! In all the years I worked to rid my gardens of the bore I found that to be absolutely true. Whenever I used to see the center leaves dying off I would cut them off at the base and carefully look through it. Only one time did I find two tiny bores and I think it would only have been a mater of time before one ate the other.
