Yes, I'm the Cannon Falls guy.
As far as the numbers of monarchs, only speaking about my farm and this area, I'd tend to agree with you. It is certainly a good year and a wonderful recovery from last. In 2001 we had two days when I estimate we had 10,000 but it only lasted two days. This year it has been a steady 2,000 to 5,000 for 10 straight days (from 8-22 to 8-31). Today 8-31 there was a fall off in numbers and we had between 500 and 1000. And yes the numbers here are definetly bigger than 03.
I'm a teacher, and school is now starting, so I went out and collected 20 or so larva of various instars. I collected them from outer areas of my farm hoping to avoid my problem. Well, now that I have captive larva I realize I have seen this problem before. It usually happens very late in the year, late September, in a warm year early Oct. What happens is the larva eat very little, don't grow much, are lethargic, don't respond to sharp noises, etc. In other words clearly sick. I believe (just guessing) it is a bacteria that is on the milkweed. I would assume it is naturally occuring and multiplies with favorable environmental conditions and perhaps aided by large numbers of monarchs. The behavior of the larva are what bt is supposed to do to larva of various garden pests in their larval stages. I will continue to investigate and experiment. Anyone else seen this in their larva?