It's not too late

Could you use some good news? Here’s some: last Thanksgiving the population of Western monarch butterflies counted in California increased by over 100-fold, from fewer than 2,000 butterflies counted in 2020 to 247,237 in 2021. 

 

Monarchs roosting for the winter

That’s not full recovery. Some experts estimate we’ve lost 80 percent of monarchs in 20 years. But it’s nice to know how resilient these butterflies can be.

    Western monarchs are genetically indistinguishable from the Eastern kind. It’s just that monarchs that live west of the Rockies overwinter in California and migrate to the Northwest for the summer. The ones that live east of the Rockies overwinter in central Mexico in the Monarch Butterfly Biosphere Reserve. Around this time of year, as the weather warms, they start their flight to Texas.

 

During the spring three or more successive generations of monarchs journey through the Southeast to the northern states and southern Canada where they spend the summer. Then in August and September another new generation starts to flutter all the way back to Mexico, a journey that takes up to two months (this Google Earth video illustrates it all). 

    Migration is necessary because monarchs can’t survive northern winters. In the mild, humid winter climate of Mexico’s Sierra Madre mountains, they roost in oyamel fir trees (here’s another fascinating video), packing together to stay warm. 

     With this successful life cycle evolved over the millennia, why did the monarchs suddenly start to disappear? The first obvious culprit was glyphosate (Roundup) sprayed on agricultural fields. Glyphosate use surged in the 1990s with the introduction of genetically modified Roundup Ready crops that resist the herbicide spray while it kills the weeds around them. 

Monarch caterpillars need to eat milkweed to survive. Milkweed toxins ingested by monarchs make them poisonous to predators but don't hurt the monarchs.

     Some of those weeds/wildflowers are native milkweeds. Monarchs need to lay their eggs on milkweeds to reproduce. Instead of finding milkweeds offering nectar and forage for their caterpillars alongside every field, the migrating butterflies now had to cross vast milkweed deserts in agricultural regions of the U.S.

Eastern native swamp milkweed is easy to grow and provides a lifeline for monarchs

     A recent meta-analysis by a team at Michigan State University, using data from thousands of volunteer monarch counts, found that glyphosate, habitat loss, and climate change have all contributed to the monarchs’ decline. In recent years, hotter weather in their northern range seems to have been a major factor.

     When we hear that climate change is the reason that species are dying out, it can sound hopeless. We’re not moving fast enough to save ourselves; how are we going to save the monarchs? But as the scientists point out, when migrating monarchs are stressed by high temperatures, that’s when they especially need lots of milkweeds and other native flowers for nectar along their path so they can stop off and refuel or lay eggs.

 

Migrating monarchs need other flowers too for energy from nectar

 
     The surge in Western monarchs shows that the monarch population has the capacity to rebound suddenly and dramatically. And the fact that thousands of human well-wishers are already helping encourages me too. This year let’s redouble our efforts to plant for native insects, and let’s be sure to include milkweeds in the mix.

 

Common milkweed is another good choice. It's a spreader.

 

Live and let live

This month Bayer agreed to pay $10 billion to people who’ve developed cancer after using Monsanto’s herbicide Roundup. Bayer plans to continue selling Roundup and still insists that it’s safe to use. The record settlement suggests otherwise. And there’s a huge environmental drawback to Roundup that doesn’t get enough attention: loss of biodiversity.

    The active ingredient in Roundup is glyphosate, which blocks the action of an enzyme that allows plants to make a necessary amino acid. 

Roundup at Home Depot

Roundup has been around since 1974, but it became a huge moneymaker in 1996 after Monsanto introduced Roundup Ready crops. These are patented genetically modified plants in which the target enzyme isn’t affected by glyphosate. More than 90 percent of US soybeans are now grown from these genetically modified seeds. Roundup is so ubiquitous that super-weeds have developed resistance to glyphosate.

Soybean field, Pennsylvania-photo Jakec

    When my garden was young, I remember being taught that while other herbicides might be dangerous, Roundup was perfectly safe. The idea was that it breaks down so fast that residues in plants and soil wouldn’t be a problem (not true).

    The most important reason to avoid Roundup, I think, is that spraying weed-killer in yards or on agricultural fields eliminates a huge reservoir of native plants—the weeds—that native insects depend on. A good example is the loss of common milkweed (Asclepias syriaca) that monarch butterfly larvae depend on. With widespread Roundup spraying, monarch populations have plummeted. 

Monarch nectaring on common milkweed

     Full disclosure: I once tried spraying Roundup when I saw the notoriously aggressive groundcover goutweed (Aegopodium podagraria) spreading around plants I’d received from a friend’s garden. 

Goutweed can easily get out of control

I planned the Roundup application for a sunny fall day. It took me two hours, because I was so fearful. I put on old clothes and sneakers, disposable gloves, goggles and a mask. 

 

I wished I had this much protection when spraying Roundup

I covered the surrounding plants over a radius of at least a yard with rags, then I carefully sprayed Roundup, trying my best to wet only the goutweed foliage. Then I had to remove the rags and protective gear and throw my clothes into the washer.

     Was it worth it? Not at all. The goutweed never missed a beat. Perhaps I’d applied Roundup too late in the season when the plants had stopped growing. The next spring, I weeded the goutweed out of the bed, taking extra care to dig out its slender roots. It never reappeared.

     As nonnative invasive plants became a focus of concern, Roundup was touted as a solution. Painting Roundup on cut stems of bad actors like Japanese knotweed (Polygonum cuspidatum) is still recommended. That’s understandable, because the plants are virtually immortal. I tried it once with no effect. The knotweed sprouted again the next spring. For my purposes, the benefits of Roundup definitely don’t outweigh the risks. Now I prefer the idea of hiring a flock of goats to eat knotweed thickets.

A goat clearing invasive plants at Travis Air Force Base-U.S. Air Force Photo by Heide Couch

 
     If we had a functioning federal government, it would ban glyphosate as well as neonicotinoid insecticides. Us against them isn’t a sustainable way to think about natural systems.

Summer gold

To my eyes, pink flowers look best in the soft light of spring. When summer sets in, I enjoy yellow and orange flowers more. I chose a yellow and blue color scheme for my new sunny perennial bed, with most of the flowering happening in June and thereafter. I’m admiring how the yellow flowers look in bright summer sun.

    The first yellow flowers of Rose ‘Kolorscape Yellow Fizz’ and cinquefoil (Potentilla atrosanguinea) have come and gone already, giving way to the deeper yellow of yarrow (Achillea ‘Coronation Gold’). 

Yarrow leaning over the deck

I’m happy to see these flowering profusely, showing that they’re getting enough sun in this location. The flat blooms are easy to see from the house as they lean away from the trees that overhang the far side of the bed. 

    Some extra color warmth is provided by the chartreuse flowers of lady’s mantle (Alchemilla mollis). I grow this plant mostly for its handsome round leaves, but the sprays of tiny flowers are charming too.

Lady's mantle has lots of small flowers

A spurge (Euphorbia x martinii ‘Ascot Rainbow’) adds its green and yellow bracts and yellow-rimmed leaves to the picture. While I wait for the perennials in this bed to fill in, I’m planning to use some of the open space to grow patty pan squash, which will also contribute yellow flowers. Meanwhile, on the deck I’m growing cucumbers, 

Squash flowers will be like these cucumber blossoms

black-eyed Susans (Rudbeckia hirta) to attract pollinators, and Mexican mint marigold (Tagetes lucida) for edible flowers.

I like black-eyed Susans, and pollinators do too

    One of my favorite weeds has volunteered again to add drama in several areas of the garden. Mullein (Verbascum thapsus) is a native of Europe, northern Africa and Asia that came to North America with European settlers and was adopted by Native Americans for medicinal uses. 

Young mullein getting ready to flower

If you’re in need of a poultice, this plant reportedly makes a good one, and it can also be used in remedies for colds, earaches, and asthma. I just enjoy its statuesque presence. In starts out as a rosette of woolly leaves, sending up a tall stalk of yellow flowers in its second year. 

Yellow mullein flowers opening along the tall stalk

Mullein pops up in disturbed ground, moving on when other plants settle in, so it’s never become a problem.

    Not everyone loves them, but I enjoy daylilies (Hemerocallis cvs). The first to bloom in my yard are yellow. 

An early daylily

I’ve planted a mix of colors in a narrow bed along the driveway where they get plenty of sun. Over the years they’ve formed fat clumps, and now we get lots of flowers through July and partway into August.

    A true orange flower is finally blooming in my insectary bed next to the vegetable garden. 

Butterfly weed, flowering at last

I’ve been trying for several years to grow butterfly weed (Asclepias tuberosa), but the plants dwindled, probably not getting enough water. Last year one took hold, and this spring it came back strong, grew bushy, and set flowers. Its cousin common milkweed (Asclepias syriaca) has also survived in another sunny spot. Between the two of them, I hope to provide food for monarch butterfly caterpillars.

Milkweed's evil twin

I'll be selling gardeners' gift baskets at the farmer's market in West Newton, MA 9:30-12:30 on June 23, June 30, and every other Saturday thereafter until October 6. Stop by and say hello if you're in the neighborhood! The market is on Elm Street between Washington Street and Border Street.

Recognizing nonnative invasive plants can be discouraging. There are so many thriving along sidewalks, in parks, and on conservation land that it’s easy to feel that it’s too late. There’s no way to weed them all out. We have to pick our battles.

Japanese knotweed (Fallopia japonica) taking over a local parkway

    One manageable thing we can do in our own gardens is to keep an eye out for black swallow-wort (Cynanchum louiseae). 

A tangle of black swallow-wort vines

This vine is popping up all over my neighborhood. The reason it’s a problem, other than its swarming over shrubs and shading them out, is that it fools monarch butterflies. 

Monarch on a real common milkweed (Asclepias syriaca)

Females confuse it with native milkweeds, to which it’s related, and lay their eggs on the impostor plant, thinking it will provide food for their larvae. When the caterpillars hatch, they can’t live on black swallow-wort leaves, and they don’t survive.

    The first black swallow-wort vine I noticed in my yard grew up from the base of a particularly thorny rose bush and twined around the canes like a morning glory. I didn’t spot it until it was 3 feet tall. I never was able to uproot that plant. I couldn’t dig deeply without risking killing the rose. 

A hard place to dig

When I grabbed the base of the vine’s stem and tried to yank the roots out, it snapped at soil level. I keep working at it every year, watching for new tendrils as they appear in spring and pulling out as much of the plant as I can. Some year, I hope, it will run out of energy and die.

    Fortunately, that’s good enough to protect monarchs. Here’s a link to a helpful guide published by Newton Conservators, a local environmental group. As they explain, it’s useful to cut the plant to the ground. Later in the season, you can even help by cutting off the seed pods and throwing them in the trash to keep browsing animals from eating the fruits and then excreting the seeds to germinate somewhere else. Like other parts of invasive plants, the pods should go into the trash, not the compost or even the yard waste. They have awe-inspiring reproductive powers.

Butterfly weed (Asclepias tuberosa) is another milkweed relative and does support monarchs

    Down the block, black swallow-wort has overwhelmed a privet hedge that grows thinly because of the shade of a sugar maple. A net of vines drapes over the low hedge, hiding it completely. That means many seeds will be ready to spread around the neighborhood by the end of the summer.

    With that kind of population pressure, I can’t expect to keep black-swallow-wort out of my yard. I’ll just have to watch for it as I deadhead, prune, and weed. If I catch the sprouts when they’re small, I have a chance to keep them from taking over.

    Newton Conservators and other groups regularly mobilize teams to pull invasives on conservation land. Will this work have to be repeated every year to keep the culprits from growing back? Let’s hope volunteers replace the unwanted plants with native species vigorous enough to hold the ground.

Swamp milkweed (Asclepias incarnata), left,
or common milkweed (Asclepias syriaca), 
right, could be good replacements for black
swallow-wort

 

Picky eaters

Something I learned from entomologist Doug Tallamy’s book Bringing Nature Home is that most insects specialize. Ninety percent of herbivorous insects depend for food and shelter on a few plants they coevolved with. This insight is directing me toward different plant choices.

    I used to think that leaf-eating insects ate any leaves they could get. Tallamy explains that, on the contrary, over the millennia insects have survived by tailoring their behavior and physiology to be able to sense and locate a few plant species. 

Not just any leaf will do for food

They’ve synchronized their life cycles with the plants’. They’ve developed ways to get around the plants’ defenses. As they’ve invested in these food sources, they’ve become less able to live off others. That’s why most need plants from their local region and can’t eat plants from other parts of the world.

North American native insects can't eat plants that originated in Asia

    This year I’ve expanded my collection of milkweeds for monarch butterflies, the poster children of insect specialization. Monarch caterpillars have evolved to be able to eat milkweed leaves, which contain defensive chemicals called cardenolides that make the caterpillars and adult butterflies poisonous for other animals. 

A monarch on showy milkweed (Asclepias speciosa)

When eggs laid on milkweeds hatch, the caterpillars have the food they need to grow and metamorphose into another generation of beautiful adult monarchs.

    Monarchs are now under great stress. They need to fly from their winter home in Mexico to summer habitat in the US. 

Wintering in Mexico-photo Steve Bridger

Here they find less and less milkweed because of herbicides such as Roundup (glyphosate) that are widely used in industrial agriculture. Organic farmers make a point of leaving weed strips around their fields for the sake of pollinators, including butterflies. Until that becomes universal practice, home gardeners are encouraged to grow some milkweed for the monarchs.

    I started with swamp milkweed (Asclepias incarnata), which turned out to be quite easy to grow. Swamp milkweed’s dusty pink flowers are clearly an insect magnet. Not only the monarchs benefit.

Swamp milkweed attracts lots of pollinators

    This year I tried butterfly weed (Asclepias tuberosa) again. I’d planted this species twice before, only to see it dwindle without flowering. With a sunnier spot and plenty of rain this spring and summer, it didn’t flower, but it seemed to take hold. I’m optimistic about seeing some of the orange flowers next summer.

Butterfly weed, not as easy as I'd hoped.

    I also started seeds of common milkweed (Asclepias syriacus) and planted a couple of seedlings. This could turn out to be a mistake, because the plant is reputed to be quite a spreader. I like the seed pods and the seeds with their parachutes of white fleece, though, and I’m hoping to see some monarch caterpillars on the leaves.

Common milkweed seed pods opening in fall

    As an experiment, I laid a half-open common milkweed pod that I found in the neighborhood on the ground in an open area near some new shrubs. Maybe the wind will pick up some seeds and sow them as it would in the wild.

    I spotted just one monarch butterfly in the yard this summer. I hope she or he will send friends.