caitlinsgarden said: That's very interesting about iris versicolor and iris virginica. I will have to research that more. Where did you find this info, Kent?
I googled and found nothing. I have both of these plants by the way but my yard had borers before I got these 2 plants.
I suspect that information will be hard to find with a google search because all of the results are geared towards control of borers in garden irises. It is, however, common knowledge among the butterfly/moth researchers I interact with on a regular basis.
If you think about it, though, it's not really a controversial statement.
1. Iris borers are native to North America.
2. The larvae are only know to feed on plants in the family Iridaceae.
3. Prior to European colonization, there weren't many options other than Iris versicolor, Iris virginica, and possibly the cristata-type irises for the borer larvae to feed on. There just aren't that many species of Irids that are native to North America. The rhizomes of Sisyrinchiums are far too small to accommodate an iris borer, Nemastylis grows from small bulbs that also wouldn't suit an iris borer, etc. The only real mysteries are that the borers don't seem to bother the Iris species that were native to the Gulf Coast (the "Louisiana Irises") and I don't think they have been found in Iris missouriensis (which is widespread in the western third of the US).
You might say that gardeners, by planting various types of irids from other parts of the world, have been a real boon for iris borers. We have greatly diversified their options for larval host plants. Even today, though, if you overlay the range map of iris borers on the combined range maps of Iris versicolor and Iris virginica, they still correlate quite nicely.
