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Managing our highways for butterflies, not pesticides

Sylvia Fallon

Posted May 8, 2014

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With news that the number of monarch butterflies is plummeting due to the use of herbicides in agriculture, people have been looking for alternative habitats to restore the butterflies’ host plant, milkweed.  NRDC has partnered with Monarch Watch to help plant milkweed at schools and non-profits all over the US.  However, given the extent of the loss of milkweed that has occurred, we would like to see an even larger effort to restore milkweed across hundreds of thousands of acres. One great opportunity for this would be to get milkweed planted along roadsides – in a sense this would create a “butterfly highway” for the monarchs to follow as they migrate from Mexico across the entire US to Canada and then back.

The only problem is that roadsides are currently heavily managed with the use of herbicides as well as mowing – both of which would interfere with milkweed growth.  Earlier this spring, NRDC filed a petition with EPA asking them to review the registration of glyphosate (the active ingredient in Roundup) as well as other herbicides in light of their impact on monarch butterflies and we are calling on EPA to impose restrictions on the use of herbicides to allow for areas where milkweed – the plant that monarchs need to reproduce – can grow.  In researching the use of glyphosate for this petition we discovered that its use in agriculture is well documented, but its use elsewhere – including roadsides – is not well tracked.  And yet we know that roadside managers regularly use glyphosate and other herbicides to manage vegetation.  In fact, a quick review shows that many states are approved to use more than 20 different herbicides in addition to mowing. 

If we are going to be able to transform our roadsides into habitat for monarchs and other pollinators we will need a radical change from the current status quo for roadside management.  But first, we will need to know more about how each state is currently managing their roadside vegetation.  Many of these decisions are made in a patchwork way at the level of counties and municipalities so getting a clear picture of management at the state level can be tricky.  This is why NRDC recently filed Freedom of Information Act requests to various states along the migratory path of the monarch butterfly asking for an accounting of their roadside management practices including their use of herbicides and their mowing practices.  We plan to use this information to help us devise a strategy for converting roadsides that are currently heavily managed with herbicides and mowing into butterfly highways for monarchs and other pollinators. 


To support efforts to plant milkweed, see our Monarch Green Gift.

 Monarch butterfly

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Michael BerndtsonMay 9 2014 02:51 PM

Fun with numbers:

From American Road & Transportation Builders:

"The Federal Highway Administration tracks the state of repair on 892,163 miles of major highways that are eligible for federal aid. In 2012, the latest data available, the FHWA found that 182,872 miles, or 20.5 percent, were in poor or mediocre condition and needed repaving or even more substantive repairs."


"There is no information on condition of the 3.2 million miles of local roads and rural minor connectors that are not eligible for federal aid. But if the same 20.5 percent are in poor or mediocre condition, then 656,039 miles of these roads would also be in need of repair. (Source: 2012 Highway Statistics, Tables HM-63 and HM-64)."

That's a lot of roads. Let's say the total miles for federal highways is 1,000,000 (based on 20 percent needing repair and rounding up).

Focusing just on the fed highways, let's assume of that 1,000,000 miles there's 50 feet of plantable land on either side and the median. That's about 10,000 square miles of land or 6 million acres. Since I'm making all this up, let's assume 1/3 of these roads are in the flight pattern of the butterfly - so that's about 2 million acres. Let's assume only half of this can be planted due to uptight folks wanting perfectly mowed highway right aways and Big Lawn Mower lobbyists getting together to fight this great idea - that's still 1 million acres of land that could be planted with plants and not get mowed.

Again, this doesn't include the millions upon millions of state and county roads.

Great idea, (who wrote this - scrolling up) Sylvia.

Jane PetersMay 11 2014 11:44 AM

Why do humans like spraying poison everywhere?

Lynda SchwemmerMay 12 2014 04:03 PM

There must surely be many farmers who would be willing to allow milkweed to grow in untilled small parcels. Is anyone reaching out to them? Many are already managing their lands with sensitivity to migrating water fowl and other creatures.

Luanne JorewiczMay 12 2014 05:57 PM

I don't know what it's like elsewhere, but in Texas (thanks, LadyBird Johnson!), we don't mow in the spring. We let the highways' green spaces just grow and grow to allow all the wildflowers to grow and spread. It's an amazing sight.

Now if we could just replace whatever the 'green' stuff is with low-growing, self-monitoring grasses and native plants, we'd never have to mow again!

Carolyn HopperMay 12 2014 06:13 PM

Obviously there has been a great deal of study done on where milkweed was growing for the last several decades and what the track of the Monarchs is so that helping farmers and cities and towns incorporate perennial plants of all the sorts that used to grow along roadsides is something that makes good sense. There are Monarchs in CT along the shore lines too.
So it's two fold - where are Monarchs now. Where were they. How long have they been tracked before the '90's? Where does it make sense to plant milkweed. What incentives can you give farmers and communities to get involved?

Cindy BloomMay 13 2014 05:00 AM

What about selling the seeds to individual's who can grow them in there on back yards, or selling them to local park & recreation areas.
I'd love to have milkweed growing among my wild flower gardens.

Sandy HarrisonMay 13 2014 12:17 PM

I would love to plant some for the butterfly;s. I have over 5 acres and do not use sprays. A good half of our place is left natural. Where can we get some Milkweed?

Lisa LowderMay 13 2014 04:52 PM

I Let my Fields go Wild to be cut for feed. I do not seed or weed or Fertilze. I have hundreds of butterflies of mine kinds; Not to mention fireflies.

Linda DemingMay 13 2014 09:49 PM

I have milkweed growing my my small field where I live but my neighbor has his field which is bigger is full of them and he mows it mid-summer so that the second cycle of monarch propagation gets cut short it seems. This is also another aspect of educating the public, as most places around here in the area of Maine I live in mow their fields to keep the fields looking "nice".

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