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Friday, July 13, 2012

Scientist update

small-4th-from-ilse-hot-sum.jpgAfter a strong, early start this spring, we are hearing reports of very low numbers for monarch populations throughout much of the upper midwestern US. While it's too early to be sure about the causes for this drop in numbers, one strong possibility is the extreme heat we've been having. Monarchs, and many other animals, have a hard time with extreme temperatures, and they don't have air-conditioned buildings to escape to, like we do! We know from work done in the U of M Monarch Lab by Reba Batalden that temperatures too much above 90 degrees F start causing problems, although if these temperatures don't last long, the monarchs are okay. Extreme temperatures cause mortality, slower development, and smaller caterpillars. The attached picture of a 4th instar taken by MLMP volunteer Ilse Gebhard in Michigan illustrates this - look at the ruler in the photo and compare this caterpillar to other 4th instars you've seen!

Thanks to the monarch groups for helping us understand what's going on with monarchs this summer!

Karen Oberhauser

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