Managing our highways for butterflies, not pesticides

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

About the Authors

Sylvia Fallon

Director, Wildlife Conservation project

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