No, this is not the start of an Eric Carle children’s book. It’s the start of a blog post all about gregarious feeders! Unlike the lone green caterpillar of the book that goes chomping through fruits and cakes and slices of salami, some caterpillars can be seen feeding and living in large groups, and as such are labeled ‘gregarious’. We have found many of these fascinating species on our grounds.
Tussock Moth
Milkweed tussock moths
Milkweed is famously host to monarch caterpillars, but many other species depend on it as well. The tussock moth caterpillar is a crazy-haired and charismatic species that seems to appear out of nowhere and turn your milkweed plants into skeletons, eating an entire plant in a matter of days!
Euchaetes egle are orange, white and black, reminding me of my grandmother’s calico shag carpet from the ’70s. As nostalgic as that may be, don’t touch! Their hairs are urticating, meaning they break off into skin and cause irritation. The Latin buffs might remember that “urtica” translates to “nettle”. It is best to let them devour the plants and go on their merry way.
What about the monarchs? Will there by any milkweed left for them? The solution is always to plant more! Try several different species of milkweed to diversify your selection and increase the available habitat.
Walnut Moth Caterpillar
Just last week I noticed a black caterpillar with wispy white hairs crawling along the sidewalk near our greenhouse. Just as I stooped to get a closer look, I saw another. And another. They were everywhere! Crawling every direction on the sidewalk, in the grass, over the rocks and up the side of the building. I followed them back to their host tree, a young walnut. These were walnut moth caterpillars, Datana intergerrimma. There I found a wiggling mass of hairy caterpillars on the trunk. They hatch on the leaves, defoliate the tree with their voracious appetites, then travel down the trunk to disperse and find a bit of open soil to dig in and pupate.
Checkerspot Butterfly
In early June we get lots of calls asking “what is feeding on my Echinacea and sunflowers, and how do I kill it?”. It is usually checkerspot butterfly larvae. These small black caterpillars are lined with tufts of black hair, and they can turn leaves to lace right before your eyes! They host on plants in the Asteraceae family, and their favorites seem to be annual sunflowers and Echinacea purpurea. Through all the years we have had major populations feeding here at the Arb, our Echinacea flowers are doing just fine with no pesticide treatment. They look a little rough for a time, but recover quickly and pop up healthy and green the next spring.
Next time you see a mass of caterpillars feeding on your trees or flowers, don’t reach for the bug spray! Use a tool like the Seek app, or BugGuide.net to properly identify them. If they are native, let them continue to eat and fulfill their ecological role!
Remember, native host plants and native insects have been evolving together for thousands of years. They battle, and sometimes even benefit each other in ways we are still studying today.
In Kansas and throughout the central U.S. corridor, we need to plant more milkweed for monarchs. Because of human-caused reductions of host plant milkweed species through the monarch migration corridor, this butterfly is in decline. I will summarize the current plight of the monarch, review its life cycle and why it is in decline, and recommend seven milkweed species we should be planting more frequently in our urban landscapes to attempt to aid monarch recovery.
Monarch on swamp milkweed in the Arboretum greenhouse. Photo by Barbara Beesley.
Plight of the Monarch
Experts monitor monarch populations by documenting the extent of area they occupy annually in their Mexican oyamel fir forest overwintering sites. While the numbers are variable from year to year, the overall downward trendline seen in the following graph is discouraging.
The following recent announcement highlights that the monarch warrants protection to stop its decline, but that too many other species needing protection are taking priority at the moment.
Monarch Life Cycle
From March to November, eastern populations of monarchs migrate from Mexico to Southern Canada and back every year. It usually takes four generations of monarchs to make this journey – two going north and two going south.
Monarch generations over a typical year from Journey North
Various species of milkweed (Asclepias spp.) throughout the migration corridor of the central U.S. play host to hungry larvae as an essential element of the monarch life cycle.
Adult butterflies completing the first northern leg of the journey from Mexico to the south central states of the U.S. including Kansas are conditioned to find milkweed plants to lay their eggs in spring. Later generations returning south in late summer are doing the same.
In a 2013 presentation at Dyck Arboretum, Monarch Watch’s Chip Taylor expressed that a loss of milkweed throughout this migration corridor is one of the top reasons for the monarch’s decline. The advent of no-till agricultural practices has been great for the efficient production of crops, but its broadcast spraying of generalist herbicides like glyphosate (i.e., Roundup) has also been very efficient at killing milkweed throughout the Plains and Midwest.
Acres converted of prairie converted to cropland in monarch flyway from Monarch Watch
Loss of monarch nectar sources through habitat destruction, widespread use of insecticides, and climate change pose additional challenges to the monarch.
More Milkweed Needed
The monarch butterfly evolved along with the presence of prairie milkweed species throughout the Great Plains and Midwest during the 10,000 years since the last Ice Age.
Just as humans have rapidly reduced the presence of milkweed in the last couple of decades, we should be able to find ways to re-establish milkweed.
In a recent presentation, I promoted the planting of milkweed for monarchs and highlighted the diversity of 19 milkweed species found in Kansas. These species are well-documented in the book Kansas Wildflowers and Weeds by Michael John Haddock, Craig C. Freeman, and Janét E. Bare. Compiling information from Chip Taylor and a 2018 Iowa study in Frontiers of Ecological Evolution on milkweed preference by monarchs, I landed on promotion of the following seven yellow-highlighted species. With high monarch larvae survivorship, and being relatively easy to establish from plugs, these seven milkweed species are good selections to grow in any sunny garden spot.
Milkweed species in Kansas
To make a dent in the recovering milkweed presence throughout the monarch flyway, seeded milkweed re-establishment should be boosted in large-scale habitat areas like in between agricultural fields, along roadsides and in Conservation Reserve Program land just to name a few. But such efforts will require coordination with governmental agencies and lots of planning. What I will propose with the rest of this post will be what we can each do with our own plots of land. Consider planting plants in native plant gardens and collect and spread seed if you have areas that are larger and less manicured.
The following seven milkweed species offer aesthetically pleasing milkweed species that are good larval hosts for monarchs and good nectar sources for a variety of insects. All milkweed photos are courtesy of Michael John Haddock (Source: Kansas Wildflowers and Grasses Website)
Common milkweed can get to be weedy in the garden, but it is easy to pull, so I don’t mind a little weeding because of the immense benefit this monarch favorite offers (prefers dry to medium soil, grows 4-5′ tall, and blooms in June to July with a very sweet fragrance).Whorled milkweed prefers dry to medium soil, grows 1-2′ tall, and blooms in June to JulyButterfly milkweed prefers dry to medium soil, grows 1-2′ tall, and blooms in June to JulyGreen antelopehorn milkweed prefers dry to medium soil, grows 1-2′ tall, and blooms in May to JuneShowy milkweed prefers sandy loam dry to medium soil, grows 3-4′ tall, and blooms in June to JulySmooth or Sullivant’s milkweed prefers medium to medium -wet soil and can be commonly found in the bottom of roadside ditches. It grows 3-4′ tall, and blooms in June to July. While a bit similar looking to common milkweed, smooth milkweeds differs with its smooth, non-hairy leaves that clasp the stem, and with more flat rather than rounded flower cluster.As the name implies, swamp or marsh milkweed likes its feet wet, prefers wet to wet-medium soil like along a pond edge, grows 4-5′ tall, and blooms in August to September
As tempting as it may be to plant tropical milkweed (Asclepias curassavica) in an annual bed or a pot, try to avoid it. Even though it can host monarch larvae and the flowers are attractive for insects and humans alike. The following article from Xerces Society provides compelling reasons not to plant tropical milkweed in non-tropical areas. Holding monarchs in colder places longer than they should, and exposing monarchs to the protozoan parasite Ophryocystis elektroscirrha (or OE for short) are two of those reasons.
Come check out our Spring FloraKansas Native Plant Festival, April 22-26, 2021. There you will find a wide selection of milkweeds and other wildflowers, grasses, sedges, shrubs, and trees to enhance your landscape for monarchs and all insects!
Spring is coming. Nature is not locked down, but continues to come to life. We notice the buds expanding and the crocus blooming. Leaves emerging from the depths and plants all around us waking from their winter slumber. As spring unfolds around us, something extraordinary is about come our way again. The Monarchs are coming.
Monarch ovipositing on common milkweed. Photo by Brad GuhrA monarch caterpillar munching on a milkweed. Photo by Brad Guhr
Providing for pollinators
The monarch’s annual spring migration north from Mexico has begun. You can track their progress through Monarch Watch and Journey North. Each year we take note of when this incredible journey passes through our area. It is amazing to think that these delicate creatures can make this trek north and south every year.
Statistics show that the monarch butterfly population in
North America has declined by over 90% in just the last 20 years. This is disheartening. One of the biggest factors in monarch decline
is the increasing scarcity of its only caterpillar host plant: milkweeds.
Monarchs can’t successfully reproduce, or migrate without milkweeds, resulting
in the species decline.
Monarchs also need other blooming native wildflowers, trees, and shrubs that provide nectar for the adult butterflies to feed upon. This habitat, critical to the survival of the monarchs, continues to disappear at an alarming rate. This natural habitat decline is taking a steep toll on wildlife of all types.
Monarch on New England Aster in the fall. Photo by Janelle Flory Schrock
Plant more than milkweed
Many of us are planting milkweeds and native nectar plants in our gardens to help monarchs survive. Here is a list of plants from our Native Plant Guide that monarchs prefer:
Perennials
Aster ‘October Skies’
Aster ‘Raydon’s Favorite’
New England Aster (Aster novae-angliae sp.)
Blackeyed Susan (Rudbeckia)
Coneflowers (Echinacea sp.)
Coreopsis
Blazing Star (Liatris sp.)
Beebalm (Monarda sp.)
Milkweeds (Asclepias sp.)
Yarrow (Achillea sp.)
Eryngium yuccifolium
Goldenrod (Solidago sp.)
Zizia aurea
Vernonia ‘Iron Butterfly’
Veronicastrum virginicum ‘Lavender Towers’
Prairie clover (Dalea sp.)
Joe Pye Weed (Eupatorium sp.)
Shrubs
Chokeberry (Aronia sp.)
Leadplant (Amorpha sp.)
ServiceBerry (Amelanchier sp.)
Buttonbush (Cephalanthus sp.)
American plum (Prunus sp.)
Elderberry (Sambucus sp.)
Viburnum (Viburnum sp.)
Buttonbush bloom
Trees
Buckeye (Aesculus sp.)
Redbud (Cercis sp.)
Persimmon (Diospyros sp.)
Linden (Tilia sp.)
Stretch the season
A greater variety of plants will attract a greater variety of wildlife, including monarchs. Try to plant several species of wildflowers with varying bloom times, providing nectar sources that stretch through the season. Different pollinator populations peak at various times through the warm months, so provide for them by having a long blooming garden. Early spring and late fall flowers can help sustain migrating species in the difficult stages of their journey. Research has shown that a lack of late season nectar sources is as crucial to migration success as milkweed. Help these insects get the energy they need all through the year!
If you plant even a few milkweeds in your own garden, you can help reverse the fortune of these beautiful insects. Support habitat and other food sources for monarch butterflies and other wildlife by planting native plants. It is always beneficial to reduce mowing, and limit or eliminate the spraying of herbicides and pesticides. You can be part of the ultimate solution, which is to provide the plants monarchs need for their life cycle. Watch for these incredible butterflies. They are coming.
One final thought I came across the other day:
“To plant a garden is to believe in tomorrow.” – Audrey Hepburn
Here at the Dyck Arboretum it can be a tricky task deciding what is a weed to be pulled and what should be allowed to grow on. Many of our beloved volunteers look to me for guidance when they encounter a plant that looks out of place. What is a weed here?
Many wonderful prairie plants carry the misnomer of “weed”, such as butterfly weed, iron weed, and milkweed. These are plants that may or may not need to be pulled, depending on where they are located. I consider a few factors: does the plant belong here or fit the theme of that garden bed? Is it annual or perennial? Will it become invasive? Is it part of a plant family that is notorious for colonizing? …and so on. Weeding will become less of a guessing game when you learn to identify some native species and particularly those nasty exotics.
While the name ‘milkweed’ might cause you to shun this plant for your garden, think before you pull! In the right area, milkweeds may be a perfect addition. They will bloom for several weeks and add a bit of important monarch habitat to your backyard. Photos from Dyck Arboretum.
“Where do they come from and how can I beat them?”
Just when you think you have weeded every last square inch of your garden, here they come again. The seed bank – dormant seed that exists in the top soil – will continue to produce more weeds as long as conditions are favorable. Seeds can lay dormant in the soil for long periods of time, waiting for adequate moisture and light levels. Bindweed seed can remain viable in the soil for up to 50 years! The seed bank is created by last year’s mature weed seeds, bird droppings, hay/manure used for mulching, and seeds carried on the wind. The good news? With regular weeding and mindful practices you will decrease your weed seed bank every year. That means pulling weeds before they seed, using carefully sourced mulch material, and disturbing the soil as infrequently as possible to reduce the amount of dormant seeds awakened by light and oxygen.
Some weeds are obvious
Bindweed with it’s morning glory bloom, Siberian Elm saplings with their small serrated leaves, and prostrate spurge with its circular, flat habit all send up the red flag. These kinds of plants look out of place right away because they lack charisma and often grow in inhospitable areas. (i.e. in driveway cracks and gravel, climbing up stems of other plants).
Some weeds are ambiguous
Virginia creeper vine seems to crop up everywhere, and are very decorative if left to grow in a good spot. But they can also be aggressive when not trimmed regularly. Similarly, a mulberry sprout (which tend to come up just about everywhere a bird flies over), could be left to grow into a nice fruiting tree if you are prepared for the berry-mess and seed spread. Plants like ironweed and Illinois bundleflower seem to pop up everywhere and, though they can be aggressive spreaders, they are also quite attractive.
Ironweed (Vernonia sp.) may at first appear as an intruder, but it produces a long lasting bloom and is visited by many species of bees. Photo from Dyck Arboretum.
Some weeds are not weeds at all
I always advocate for leaving milkweed in the garden as habitat for monarchs. Lucky you if a few come up! Other species like purple poppy mallow and wild petunia that may appear weedy at first actually make well behaved native specimens. These species bloom all summer long and are extremely drought tolerant.
While you pull and pluck away at the weeds in the garden, remember the wise words of the poet Ella Wheeler Wilcox – “A weed is but an unloved flower”. Although weeding is the tedious task all of us gardeners must endure, you can make it easier and more productive by knowing the difference between potential friend and foe.
Monarchs ingest toxic cardiac glycosides when their larvae eat milkweed leaves and advertise through their adult warning coloration: “look out for me…I’m poisonous!” The U.S. Fish and Wildlife Service may very soon be issuing its own warning on behalf of declining populations for this bright butterfly under the banner of the Endangered Species Act (ESA). A petition was submitted in August 2014 by The Center for Biological Diversity, Center for Food Safety, The Xerces Society, and Dr. Lincoln Brower to encourage listing of this species on the ‘threatened’ list. A ‘threatened species’ is one that is likely to become endangered in the foreseeable future throughout all or a significant portion of its range.
Dramatic Population Decline
The following graph (Graph courtesy of the Monarch Joint Venture) shows over the last 20 years the area of monarch overwintering colonies in the forests of Central Mexico, which is their only overwintering location.
Figure from Monarch Watch
Their population trend of precipitous decline is discouraging. The part that is encouraging, however, is that we know exactly what the problem is – prairie habitat loss; specifically, the loss of milkweed (Asclepias spp.), the monarch host plant. Americans do not like to be restricted or forced to spend money on anything and a threatened listing under the ESA will do just that. It is my hope that we can avoid listing of the monarch butterfly and restore its population, but this will require both education and action. The action part is what I will address here. If you live in the following monarch corridor, you must take action now.
Figure from Monarch Watch
What Can We Do?
It can be fun, easy, and rewarding to establish milkweeds and I challenge everyone reading this post to take personal action in increasing milkweed populations in the coming growing season. There are two easy ways to do this: 1) establish milkweed plants in the areas you landscape, and 2) distribute milkweed seed in a nearby unmowed area.
Plant Milkweed Plants – Landscaping with native plants is rewarding and South Central Kansans have eight commercially-available native milkweed species they can plant, including Asclepias incarnata (swamp milkweed), syriaca (common milkweed), A. tuberosa (butterfly milkweed), A. viridis (green antelopehorn), A. speciosa (showy milkweed), A. sullivantii (smooth milkweed), A. hirtella (prairie milkweed), and A. verticillata (whorled milkweed). These species can be purchased at the Dyck Arboretum of the Plains spring plant sale, Monarch Watch, and Prairie Moon Nursery. Plants establish and flower in the first year with proper care and provide beauty and insect nectar sources in addition to host plant larval food for the monarch.
Showy milkweed (Asclepias speciosa)
Distribute Milkweed Seed – Surely you know a grassland area along a nearby creek or waterway, in a park, or along a roadside that gets mowed or burned only periodically to keep it free of trees. Collect some seed from a nearby prairie or even buy some seed of the species above from a native seed nursery (good sources include Prairie Moon Nursery and Missouri Wildflowers Nursery), get permission to plant, and distribute your milkweed seeds in the fall or early winter so that germination will happen and establishment will begin the following spring. Common milkweed ( A. syriaca) is the species most preferred by the monarch and is easiest to acquire and establish. Distributing seed is a very cost effective and easy way to establish milkweed were it doesn’t currently exist.
Common milkweed (Aslepias syriaca) with monarch eggs
Do you remember the massive flocks of the passenger pigeon? Of course you don’t – Martha, the last known individual died in 1914. Your grandparents or great grandparents, however, may have been able to tell you first hand stories. First hand experiences with monarchs may be something we currently take for granted. If we don’t act now, these encounters with monarchs may be something our grandkids or great grandkids never experience. Don’t let this happen.
