I found a report from the Pew Trust that has some information on this:

Here is a link that might be useful: Update on modified corn and monarchs

I've been a pretty crummy observer this year. I haven't seen any Monarchs, but sure did have my usual crowd of Monarch caterpillars on my milkweed!

I thought there were lots of monarchs in my yard, particularly since I don't have any milkweed (yet). But I am perhaps not the best source, as my former observations were up north - and AL has way more butterflies of all kinds than I ever saw in MA.

I live in Pinson and have seen a few monarchs and a ton of others. More than I have ever seen here.

I have not seen all that many monarchs but lots of the black and blue butterflies, I believe thry're called spicebush swallowtails (they like my periwinkles).

I can't say many or few but when I have my camera along, I try try to capture............

{{gwi:368725}}

There have been occasional ones all year, and now that they are migrating, I am seeing more of them. Several of them were "playing tag" in my garden this morning.
kay

I've seen more than usual this year if anything. But I've seen a large number of butterflies overall this year as well. My first Monarch sighting was about 3 weeks ago and the most recent was yesterday. Was out of town all last week and I'm gone all day and don't really look hard for them every day, just when I'm browsing around the yard at the end of the day. Loads of Gulf Frits, Spicebush, Black & Eastern Tiger Swallowtails and Cloudless Sulphurs this year.

When I see pictures like that, terramadre, I really appreciate how crazy gorgeous those insects are. Just spectacular.

I live in a suburban setting of the western Tennessee Valley of Alabama. We never have a lot of Monarchs in this immediate area but I see a few. My concern has been the declining number of Cloudless Sulphurs that we have observed the last few years....My thought was, the increased usage of herbicides in connection with the no till farming techniques are to blame . I know that the Cassia plants and Milk weeds that the Sulphurs and the Monarchs depend on proliferate around agricultural fields.

I had two monarchs visit my milkweed last week.

I have had enormous numbers of cloudless sulfurs this year. They have been here most of the summer with really large numbers migrating. They particularly like the zinnias and the Navajo and Hotlips salvia. They are very fond of ground that had been wet with sprinklers.

kay

I've had large numbers of cloudless sulphurs this year and I'm also in the heart of the TN valley. I thought they might have been gone, but today I probably have had half a dozen flitting around me while I was cleaning up the garden. I'm leaving the zinnias until a freeze gets them. There were a few other small butterflies that I haven't ID'd yet, and I saw a GF yesterday at the lake. The Monarchs apparently have migrated on to the south since you're seeing them down Mobile way now, jcalhoun. I haven't seen one for a couple of weeks.

There have been quite a few here on the bay during the past couple of weeks. I'm either not a good observer from year to year or 'old-timer's' prevents me from comparing their numbers to last year. ;)

Thanks for the link to the article, catbird, re: GMO corn/monarchs.