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College of Food, Agricultural, and Environmental Sciences


Smart Stuff with Twig Walkingstick (for the Week of Jan. 7, 2007): Warmer Winters, Sooner Weevils

December 21, 2006

Q.: Dear Twig: How do scientists know there's global warming — global climate change — going on?

A.: The short answer: research. I'll start with one example from my home, Ohio State.

Dan Herms studies insect pests that bother trees and shrubs. He helped come up with and now helps run a special biological calendar. The calendar tells when pests will show up. (Gardeners find this good to know.) It does this based on the bloom times of plants. It shows, for instance, that black vine weevils come out at the same time as locust tree flowers.

(The key to the calendar? Temperature. It controls the development of both bugs and of buds.)

But Dan's work turned up something else, too: that the locusts now bloom and the weevils now weevil about three weeks sooner than they did in 1970.

Why? "Winters are getting warmer," Dan says.

Next: From locust trees in your own back yard to the snows of Kilimanjaro!


P.S. Learn more about Dan's work at


Notes: An associate professor in Ohio State's Department of Entomology, Dan Herms has appointments with both OSU Extension and the Ohio Agricultural Research and Development Center. Both organizations, organizationally speaking, are in the College of Food, Agricultural, and Environmental Sciences. The source for this column and the link in the postscript is an Ohio State press release titled "Global Warming in Your Garden? Common Plants, Bugs Reveal Important Climate Changes." Find (and try!) the biological calendar at Send questions for Twig to his bud, Kurt Knebusch,

About this column: "Smart Stuff with Twig Walkingstick," a free public service of The Ohio State University College of Food, Agricultural, and Environmental Sciences - specifically, of the Ohio Agricultural Research and Development Center (OARDC) and Ohio State University Extension, both part of the College - is a weekly column for children about science, nature, farming and the environment. The reading level rates at grades 3.5-4.5. For details, to ask Twig a question, and/or to receive the column free by mail or e-mail, contact the writer, Kurt Knebusch, CommTech, OSU/OARDC,1680 Madison Ave., Wooster, OH 44691,, (330) 263-3776. Online at

Kurt Knebusch