Skip to main content

Society for the Protection of New Hampshire Forests

Get our e-news!

Sign up

small nav

  • About Us
    • Staff
    • Board of Trustees
    • Our History
    • Contact Us
    • COVID-19 Updates
    • Partners
    • Business Members
    • Annual Reports
    • Bylaws
    • Policies
    • Conservation Center
    • Employment
  • log in
  • Facebook
  • Twitter
  • Instagram

Main menu

  • What we do
    • Land Conservation
    • Education & Events
    • Advocacy
    • Forestry & Recreation
    • News & Features
    • Forest Notes & More Publications
  • Current Projects
    • Mount Major Stewardship Fund
    • Forest Society North at The Rocks Campaign
    • Clay Brook Forest, Hampton Falls
    • Stillhouse Forest Addition, Northfield
    • Moose Mountains Expansion
    • Merrimack: River at Risk
    • Weeks Woods - Rene and Elizabeth Gilbert Tract, Gilford
  • Visit & Explore
    • The Rocks
    • Conservation Center
    • Forest Reservation Guide
  • Get Involved
    • Upcoming Events
    • Membership/Renewal
    • Support Our Work
    • Take Action
    • Volunteer
    • Subscribe to E-news
  • Search

Search form

Donate
Menu

News

  • Cold is Cool Speaker Series Continues

    Anna Berry
    January 20, 2021

    Plug in to watch and learn from expert speakers and then unplug outside.

  • A New Way to See the Merrimack Watershed

    Anna Berry
    January 12, 2021

    Thanks to the Clean Water Act of 1972, the Merrimack has been cleaned up considerably over the last 50 years. But there is still work to be done.

  • Something Wild: Flying Under the Radar

    Dave Anderson, Chris Martin, Emily Quirk
    January 5, 2021

    Sometimes called a Marsh Hawk, the northern harrier is currently one the rarest birds of prey nesting in the Granite State.

Monarchs, Milkweed and Mowing

Hail to the Kings and Queens of Butterflies
Jack Savage
August 15, 2019
Wildlife
Stewardship
Monarch at Tom Rush Forest
Among the most fascinating facts about Monarch butterflies—while one generation of adult monarch will migrate south, it takes three or four generations to return. Photo by Jackie Sawyer

There’s an odd pleasure that comes from climbing on a tractor and mowing a field. You can measure your accomplishment of the task in the neat parallel tracks that the tractor lays out behind the bushhog. It speaks to the desire to impose your own sense of order on what can sometimes appear to be the random chaos of nature.

And around here if we want field habitat, we need to graze or mow. As the adage goes: How do you grow trees in New Hampshire? Just stop mowing. The field will become forest.

Milkweed at Tom Rush Forest, Photo by Gabe Roxby
In recent decades we’ve learned that if we’re not haying, it’s better to push off field mowing to August or September for the benefit of certain wildlife species. Better to wait until the bobolinks (which only nest in fields and pastures) have fledged and deer are less likely to be secreting a fawn in the tall grass.  (For me, this is all retroactive justification for annual procrastination.)

More recently, there has been broader recognition of the importance of milkweed to the proliferation of monarch butterflies, which have experienced significant declines in population. Thus, on the few acres of open field on our Tree Farm the mowing regimen has been altered again. Those neat mowed rows are interrupted as I direct the tractor around groupings of milkweed. I’ve seen the ‘milkweed swerve’ elsewhere in fields where it looks at first glance like the mower missed a few spots.

Milkweed is essentially the nursery for monarchs. After mating, mature monarchs seek out milkweed to lay eggs on the underside of the leaves. Monarchs have evolved to rely on milkweed for their very survival.

First, when the eggs hatch, the milkweed is a food source for the larvae (caterpillars). The caterpillars are immune to the mildly toxic nature of the milkweed plant, and by ingesting it they themselves become protectively toxic to other species that would otherwise make the monarch a tasty treat. The caterpillars become a pupa (chrysalis) before emerging as an adult butterfly. Their coloration is a warning to others—“eat me at your own risk”.

Photo by Andy Crowley

Adult monarchs don’t eat milkweed—they are important pollinators for a variety of other flowering plants.

The also migrate. The Eastern Monarch that we encounter in New Hampshire travels thousands of miles, at an average of five and a half miles per hour, south/southwest toward an into Mexico. (With our help, they’ve also even been to space, having been transported to the International Space Station and bred there.)

And among the most fascinating facts—while one generation of adult monarch will move south, it takes three or four generations to return. As they make their way back north, it is the offspring of each generation that continue the journey. How those great grandchildren know the migration route is not fully understood.

It’s become the fashion to breed monarchs by fostering the eggs and larvae indoors (in a jar on the porch, on a small scale). But some recent research indicates that monarchs don’t always end up with the same sense of direction when bred in such conditions—at least in larger quantities. In the study, butterflies raised indoors failed to fly south.

On the Forest Society’s Tom Rush Forest, we are managing the fields there to enhance common milkweed, which is being threatened by an invasive, black swallowwort. While black swallowwort is in the milkweed family, it is toxic or indedible for the monarch caterpillars and they don’t survive, and the swallowwort displaces common milkweed.

So next time you climb on the tractor or lawn tractor to satisfy an urge to bring order to nature, take a moment to look more closely at what might be in your path. The fate of a few hundred butterflies may be in your hands.

Jack Savage is the Executive Editor of Forest Notes, the quarterly magazine of the Society for the Protection of New Hampshire Forests. To find out more about the Forest Society, visit www.forestsociety.org.

Footer menu

  • Privacy Policy
  • About Us
Society for the Protection of New Hampshire Forests54 Portsmouth St.Concord, NH 03301
Phone: 603.224.9945Fax: 603.228.0423info@forestsociety.org
Land Trust Alliance accreditation logo