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Milkweed for monarchs
Sept. 28, 2015

Associate Editor

HOWARD LAKE, MN – Years ago, Wally McCurdy and his wife, Linda, used to walk through the grove on their rural Howard Lake property and watch “millions of monarchs” rest in the trees.

“Now, I’m lucky if I see a few,” McCurdy said.

Linda passed away in March 2014, but McCurdy hasn’t given up his wish of seeing kaleidoscopes of monarchs once again.

According to The Reporter in Fond du Lac, WI, the monarch population has decreased 80 percent in the past two decades, and three of the lowest overwintering populations have been recorded within the last 10 years.

The reasons for the decline are numerous. Monarch Watch reports that unusual winter storms in central Mexico devastated the population, killing 80 percent in 2002 and 50 percent in 2010.

Loss of habitat is also critical – 100 million acres have been lost in the past 10 years due to Roundup-ready corn and soybeans, and about 2.2 million acres are lost each year due to development. Monarch Watch states that 7 million acres of Conservation Reserve Program (CRP) land was converted to crops for the production of biofuels, further reducing habitat.

The US Fish and Wildlife Service notes that increased mowing in roadside ditches may also contribute to the loss of milkweed – the only plant on which a monarch will lay her eggs.

Near Howard Lake, in Middleville Township, roadsides are generally mowed three times per year – mid-June, late July/early August, and late September/early October.

Maintenance supervisor Randy Klugow said he only makes one pass (about 5 feet wide) in the summer months, and two passes in the fall.

“The county’s mower is wider, and might take 10 to 12 feet at once,” he said.

Klugow commented that he mainly sees foxtails and thistles near the road, while milkweed is further down into the ditch.

In the summer, the ditches are mowed “mainly for safety reasons,” according to Klugow.

Cornell University states that mowing helps maintain sign visibility, keeps saplings from growing into trees, defines the roadway, provides better drainage, and improves aesthetics. These factors, along with the type of vegetation in the ditch, help determine how often mowing should take place.

In the fall, Klugow said he mows two passes in order to prevent snow drifts in the ditches.

“Once it starts drifting, you can’t really get rid of it,” he said.

According to Klugow, the use of Roundup-ready crops (which were introduced in 1997) is a much larger contributor to milkweed decline than mowing.

“That kills all the milkweed,” he said. “The area used to be thick with butterflies; now, I hardly see them at all.”

Insect ecologist Orley Taylor, who has been studying monarch populations for decades, agrees. In an article in the Yale Environment 360, he states that “. . . the most productive habitat for monarch butterflies in the Midwest, in the Corn Belt, was the corn and soybean fields [where milkweed, which monarchs feed on, grew]. Before Roundup-ready crops, weed control was accomplished by running a tiller through those fields and chopping up the weeds and turning over the soil, but not affecting the crops. The milkweed survives that sort of tillage to some extent.”

How to help
In order for the monarch population to recover, Taylor notes that people will need to create more places for milkweed to grow, such as planting it in their gardens.

According to ecology.info, more than 90 percent of monarch eggs and caterpillars die before they reach adulthood. Learner.org reports that monarchs usually have a much higher chance of survival when raised in captivity.

For information about raising caterpillars, go to http://monarchwatch.org/rear/

Note: This article was written with help from Herald Journal Correspondent Tara Mathews.

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