Where is the borer-border?

I just had a message from Denise mentioning that they don't have borers west of the Mississippi River. Except that Iowa is also west, so the line must be further west than the river? Where would I have to move to be free of borers?

There is a map on the Garden Shield website that designates the states known to have iris borers, but I don't know if it's perfectly accurate. Anyhow, you can find it here:

http://www.gardenshield.com/

BTW, I'm about 20 miles west of Old Miss, and borers have certainly been present here.

Laurie

Well, I'm about 400 miles west of the Mississippi, and I have iris borers.

I see that map does include North Dakota though, so I think it's probably accurate. I don't know anyone in Montana that gardens or I'd ask them if they have iris borers. The map doesn't include Montana.

I got a borer in a shipment of iris last year from a vendor and if it weren't for some very sharp eyes looking at my garden the borer would have been missed. And that's very discouraging. It's a good thing that I've hung out at DG so long or I wouldn't have known what I was seeing.

So I guess that they could be anywhere.

Thanks guys. You rescued my garden!