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Showing posts from February, 2012

Winter Cutworm

Jeffrey Hahn, Extension Professor and Asst. Extension Entomologist

Marge Kelley
Photo 1: Winter cutworm There have been a number of reports this winter of caterpillars active on top of the snow. This mystery caterpillar is an exotic moth known as Noctua pronuba, commonly called the winter cutworm or (large) yellow underwing. The first report this season came from Itasca county in December. Then on New Years day, after we had a light snowfall, there were several reports of this insect in Washington county in the eastern Twin Cities area (note: there were also a number of reports across the border in northeast Wisconsin). One person said they found about 30 of these caterpillars while another said they saw as many as 60 - 70 at a time.

There is a precedent to seeing insects outdoors during the winter. Insects, including snow flea, snow scorpionfly, and small winter stonefly, are know to tolerate colder temperatures and can be found on top of the snow during winter. Now we can add winter…

A Look at the New USDA Hardiness Zone Map

A hardiness zone map (HZM) provides information that gardeners and professional horticulturalists use in determining which herbaceous and woody perennial plants will survive cold temperature in a particular geographic area. Last week the United States Department of Agriculture released a new hardiness zone map to replace the older 1990 version.
As with past maps, the new map:is a visual representation of average annual minimum temperatures across the United States. Data points used to create the map were the lowest daily minimum temperatures recorded at thousands of temperature data stations during each of the years sampled.
divides the U.S. into multiple hardiness zones with 10o F differences in average annual minimum temperatures. Zone 1 is the coldest zone (-50o F to -60o F).
divides each hardiness zone into "a" & "b" with "a" being the colder half of any zone and "b" the warmer half.
There are changes in the new map and the process that …