Mowing for monarch habitat?

[Jeff Serena]

I'm new to this forum and apologize in advance if the point of this post is already well known to this community of butterfly experts. I tip my hat to all of you for your conservation efforts on behalf of the monarch.

I live in southern Connecticut. There is a weedy field near our house of perhaps three acres, and there is some common milkweed among the grasses and brambles. The owner mows the field occasionally to keep it from returning to early-succession woodland. This past summer, he mowed only part of the field, perhaps a half-acre, in mid June.

My seven-year-old daughter Juliana found two fifth-instar monarch caterpillars in early September on the edge of a nearby commercial orchard. She wanted to raise them to butterflies, having seen this done in her classroom last year, so we brought the caterpillars home. Juliana and I searched the weedy field near our home in a successful effort to find a convenient source of fresh milkweed. We also found more monarch caterpillars on milkweed plants in this field.

Here's what I found interesting. In the part of the field that was mowed in June, we found 35 monarch caterpillars, second to fifth instar, on common milkweed plants that had grown up since the mowing. These plants were fairly small (about 10 to 22 inches high, about 15 inches on average), green and fresh-looking. We checked approximately 105 plants in this mowed part of the field. We also checked for caterpillars on milkweed plants in the unmowed part of the field. We checked about 70 plants in the unmowed part of the field. These were obviously older plants, all of them well over 24 inches high and typically with extensive foliar damage and considerable yellowing. We found no monarch caterpillars on these plants.

I suspect, just as a guess or hypothesis, that the adult females select fresher, younger, greener milkweek plants on which to lay their eggs. In this part of the country, June mowing may provide more of these plants than an unmowed field does. In short, properly timed mowing may be a way to provide superior egg-laying habitat in fallow fields for late-summer monarchs, and may be a fairly straightforward way to promote monarch conservation.

Thanks all and best wishes,

Jeff

[texas butterfly]

Your hypothesis makes sense to me.

I'd look for the younger fresher milk weed plants too.

Maybe to the Monarch butterfly they smell sweeter.
And thus is a more attractive place to lay eggs.

I wonder if the predators is less or more on the younger milkweed also.

Could predators have been in higher number on the older plants?

[Mona Miller]

You are right, it may provide what the Monarchs need, but is probably killing other butterflies and wildlife (ground nesting birds).

Dr. Chip Taylor posted something on mowing:
"The best times are either early spring while the vegetation is still brown and before milkweed and other perennials have emerged -- or -- late fall after the growing season, being careful not to cut too close. Close cuts in the fall minimize the available micro-habitats for a variety of overwintering organisms and in some regions would allow the colonization of the area by winter annuals (plants whose seeds germinate in the fall)."

"Mowing in early spring will provide lots of succulent vegetation for larva later in the season. But it will prevent seed production. Mowing after a killing frost will knock down the seeds that the birds need. That is why a once in three years plan is the best compromise. Gary Stell, Auburn, NY"
(Mona's Note: Gary propagates milkweeds)

"My MLMP site at, a local nature center, is done every three years and seems to work well. I encouraged them to wait until mid October to mow. Here in central Michigan, we have had a frost, seeds are dispersed and nesting is completed. Another area that I survey was unable to do their controlled burn one year and it was early May before ground conditions allowed mowing, which presented a some abnormal changes. Trying to mow in the early spring in northern states can create it own problems. DENNY BROOKS Mid-Michigan Monarch Field Study Midland, Michigan"

[Jeff Serena]

Hi Mona,

Of course you're right that mid-June mowing would have a deleterious effect on some wildlife in a field, although it may also create superior habitat for other species besides monarchs. A gentler alternative--one that we're planning to use around the margins of my daughter's elementary school next June as a test--is simply to cut the milkweed plants by hand to see if better plants for late summer/fall monarchs come back.

All best,

Jeff

[Monarch MaMa]

I found more eggs and first instars on milkweed under 12" than on those over 12" tall. I agree that the younger plants may 'smell' more attractive to females but perhaps there are fewer predators on a teeny milkweed than a large one. However if there are no short young milkweed, the ladies will put their eggs on 5' - 7' tall mw's also. I've just learned to check each plant, even those without chew holes because a cat may have just crawled on it from another chewed up mw.

In my area, people have trimmed the milkweed in the ditches near the roadway on occasion. The plants that spring up afterward seem more vibrant and fresher than those without being weedwhacked, and I've found 3-5 instar on these shoots. Fortunately these cats found a timespan inbetween weedwhacking and I found them just before the last weedwhack cutting so they could finish growing up safely in my containers and fly to Mexico. I took pictures of these gorgeous cats and plan to send a note to the homeowner in May to ask them to call me before they weedwhack so I can harvest as many cats as possible to save them. They'll probably think I'm a lunatic but they may be right.

[Jeans]

hi
I was wondering about this too, there is a weedy field right beside my house too that hasn't been mowed in like, 7 years and in the fall, all the flowers are really pretty because of all the bushes and pretty "weeds." but the milkweed is really tall and yellow, and its hard to find monarchs. last year I found a spot with LOTS of milkweed, all really tiny and the spot gets mowed about once or twice a month. its the healthiest milkweed i've ever seen and there is usually at least one egg on every plant. its right by the river too so I wonder if that helps. would it be better to go to the weedy field with scissors and trim the milkweed? I wouldn't want it to get mowed because i don't think the other plants would enjoy that, plus the field is a favourite to the other butterflies and bees too.
thanks

[Mona Miller]

I found this article about how to mow.

Stop destructive mowing
By Chip
Created 11/13/2008 - 01:08

Untimely mowing is one of the most destructive <strong>and
controllable</strong> practices affecting biodiversity of our ecology
in local watersheds.
Untimely mowing by agencies (or contractors of) such agencies as
Pepco, State Highway Administration, & Department of Public Works as a
management process is one of the most destructive and controllable
practices affecting biodiversity of our ecology in local watersheds.
Biologists, Ecologists, and Botanists tremble when they observe the
late September-October mowing of native flora and habitat in important
locations of many Pepco ROWs-- especially those scientists who are
aware the the critical interdependence between our native flora and
native species such as Quail.
The native Desmodiums, Lespedezas, Senna/Cassias, and myriad of native
grasses would have all served as vital sustenance for our local native
fauna, especially our declining non-migratory Quail who cannot survive
the winter without the rich, high-protein nutients found in the seeds
of these important native species. (The grasses: Sorghastrum nutans,
Schizachyrium scoparium, Eragrostis spectabilis, Danthonia spicata,
Andropogon virginicus, Panicum anceps & virgatum, and another half
dozen or so of the major grasses with some rapidly declining species
such as Bouteloua curtipendula.)
A Pepco ROW, containing these species of native flora, that is mowed
in August, September or October (or any time in late fall or winter)
will effectively eliminate any non-migratory populations of native
fauna, especially Quail, that rely on that specific native flora/food
in that ROW for their year-end and winter sustenance.
Pepco's best intentions can be demolished in the space of one day by
untimely mowing of important ROW habitat by Mowing Contractors having
a different expediency.

As to timing of mowing of native flora and habitat: Most conservation
ecologists recommend staggering the timing of mowing so that 100% of a
specific location is never mowed at the same time. While food is a
critical part of survival of our native fauna, structure for breeding
and nesting should also be considered critical. Mowing that is
conducive to preservation of native biodiversity and nesting sites for
migratory avifauna would never be done during the breeding season.
This is generally recognized as between April 15th to August 15th for
migratory birds.
However, our non-migratory avifauna, such as the goldfinch, often
breed later into the year. Finally, some of our other native,
non-migratory avifauna such as Quail, depend on the seeds and cover of
our native flora in Pepco ROWs well into early Spring.
So, you can see that staggered mowing times for a specific location is
one of the most effective ways of dealing with the biological
conundrums described above. Unfortunately, this requires a bit more
planning than the average Mowing contractor has provided to date.
Also, identification of native flora is not usually part of the
skillset of Mowing contractors.
It is not difficult to see why many of our native avifauna have
declined significantly and continue to decline at approximately 2%
each year. This would include the edge and field (shrub, scrub and
grassland) species in the context of Pepco ROWs as habitat.
Untimely mowing is one of the most destructive, but controllable,
management decisions affecting our native ecology throughout local
watersheds.

Solutions:
Never remove, by mowing, 100% of areas containing significant
biodiversity of native fauna and flora as habitat, which supplies both
food and protection to native non-migratory species of birds. Plan the
management/mowing of these important areas by staggering the amount of
area mowed in any given year. This protects our native species such as
Quail and other winter birds.
Never mow during breeding season for migratory species --between April
15th and August 15th.
Non-migratory avifauna such as Quail, depend on the seeds and cover of
our native flora in Pepco ROWs well into early Spring.

Contact Person:
Randy Pheobus
Professional Title:
Chief Protector of Native Plains
Advocate of protection for native flora and fauna. Long-time activist
in south county working to protect quality of life for residents.

Contact Details:
Primary Email Address:
NativeGrasslands@aol.com
Work Phone Number:
(301) 440-8915
Primary Mailing Address:
PO Box 1322 Upper Marlboro MD 20773-1322

[Paul Cherubini]

would it be better to go to the weedy field with scissors and trim the milkweed?

Yes, but the timing is pretty important. If you live at approximately the latitude of Toronto (43 degrees N) the monarchs that migrate to Mexico are mostly the ones that emerged from their chrysalids between about Aug. 20 - Sept. 20. And the eggs that produced those butterflies were laid between about July 15 - Aug. 10. So to make small tender milkweeds available for the female monarchs between July 15 - Aug. 10, you should trim the milkweed about a month earlier; i.e. around June 15-30.

If you live in northern Ontario around 49-50 degrees N latitude the monarchs that migrate to Mexico are mostly the ones that emerged from their chrysalids between about Aug. 1 - Aug. 30. And the eggs that produced those butterflies were laid between about June 25 - July 25.

[Mona Miller]

When mowing I hope all will consider managing for all wildlife.

If you put "mowing, wildlife management" into Google search www.google.com, you'll get loads of information from many states and agencies.

[blazing star]

We use early Spring controlled burns on our land for the purpose of excluding invasive brush and trees in our prairie. It's not a perfect systems as some critters are still active but there is much less chance of killing something. There's a lot of training involved with controlled burns as they can be dangerous, of course. If you have a higher quality area with a lot of different insects, you can burn different sections each year to preserve the biodiversity that may exist. Then, you could just cut the milkweed of concern, possibly.