Royal Conundrum - Killing the Monarch Butterfly with "Kindness"

The monarch butterfly population has been in serious decline for years now, something many gardeners know. To compensate for habitat loss, gardeners have been encouraged to plant more milkweeds, the insect's larval host plant. But this has led to unforeseen negative consequences, especially in warm winter regions of the U.S.

Native milkweeds can be hard-to-impossible to find, so the tropical, showy "scarlet" milkweed has become ubiquitous in garden centers across the country. This plant, Asclepias curassavica, is native to the American tropics and has spread to pantropical regions worldwide. It has become invasive in some areas, and threatens to become a pest in South Florida. 

Many monarch butterflies harbor a protozoan, Ophryocystis elektroscirrha (OE), that can weaken the adult, prevent the pupa from emerging from the chrysalis, or deform the wings. Monarchs visiting milkweeds deposit spores when they visit milkweeds. Normally, migration culls weakened individuals, and the OE spores die when the plants die back in winter. The plants grow back in spring and summer with fresh, uninfected leaves. But in areas with warm winters tropical milkweed grows all year, thus maintaining high levels of OE spores. Areas of Georgia, coastal Carolinas, Florida and the Gulf Coast have become hotspots of infection.

Monarch on Scarlet Milkweed

Apart from the immediate threat to individual monarchs, year-round milkweed is also, probably more ominously, threatening the migration itself. The presence of the milkweed affects the butterfly's hormonal balance, and works as a trigger to make it reproduce. So monarchs that find themselves in areas with warm winters don't migrate, and a year-round population gets established. With increasing warming trends this area of permanent, sickly individuals will only increase. 

Migration plays a critical role in maintaining a robust gene pool, for it culls badly infected individuals, which simply don't survive the trip. But migration may play other vital roles as well, in ways  we haven't discovered. 

Some organizations like the Xerces Society and the Florida Native Plant Society actively campaign against the use of tropical milkweeds. Some people, though, citing the drastic declines in the monarch population, feel that keeping the numbers up is of primary importance. 

Weaning gardeners away from tropical milkweed is going to be a monumental project, especially since it was promoted so aggressively as a solution to monarch population decline. 

Monarch on Asclepias curassavica

In and of itself, I'm not particularly heartbroken over the loss of scarlet milkweed in our yard. Due to neglect, they've sort of died out this spring anyway. It is a water hog, and the stems quickly get leggy and woody. It also is a magnet for aphids and spider mites, which would make any self-respecting female monarch look for greener pastures. 

Aphid-Infested Milkweed

Finding natives or even native seeds, is going to be a long, drawn out process. Some mail order nurseries offer native milkweed species that theoretically would grow here, but I'd have a better chance with offspring originating  much closer to home. 

Even though they might be the same species, a plant grown in the mid-Atlantic or Midwest would be quite different genetically from one that has adapted to South Florida conditions. They might not even look the same, they might not  survive, and they certainly wouldn't do anything to maintain genetic diversity. Ecologically even North Florida differs greatly from the southern part of the state.

Asclepias incarnata, "Swamp Milkweed," a Native

But there's a further complication!

Whether it comes to weather patterns, the density of bear fur, and many other things, matters often are much more complicated when it comes to the southern peninsula of Florida. It seems that there is an established, non-migratory monarch population south of Lake Okeechobee.  The most-studied migration routes don't cover us, especially on the sw coast, though we might get a few strays. I have had basically year-round monarchs since I began butterfly gardening around 1995. Over the years I have seen newly-emerged monarchs with deformed wings, but not a lot. Even without the scarlet milkweed, all of our native milkweeds might not go completely dormant during our winters, so a small population could persist theoretically without our help. The assumption has to be that the infection rate in our monarch population is close to 100%. 

So, in a way, it doesn't matter whether we keep planting Asclepias curassavica, but it goes against the grain now that I'm aware of a problem. While I don't like the plant, and getting rid of it would not stop the problem of diseased butterflies, it still seems somehow that replacing it with its cousins that "belong here" would be ethically as well as esthetically better. Now comes the hard part - actually doing it. 

May - Prelude to Summer

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Where has May gone? I feel the time running through my hands like water. ( I stole that image from my sister-in-law,  E.).

Apart from a few afternoons, it hasn't been terribly hot yet; in that regard it clearly is not summer.

South Florida does have seasonal patterns. Things start happening by late February or early March, and the pace gets increasingly hectic until the onset of drowning rains and crushing heat of deep summer applies some brakes.

Every plant and animal seems intent on reproducing. For plants that means germination, growing, flowering, seed production all at a dizzying rate. I can't draw fast enough to record the abundance, much less the process.

Despite drought*, abundant sunshine and seemingly incessant wind, the yard is full of furiously blooming plants, crowding each other, sprawling over each other, all vying for the most light. White and lavender Heliotropium groundccovers, Gaillardias, Coreopsis, Dune Sunflower, Camphor Weed  (Pluchea rosea), Goldenrod, Blue Porterweed, Gopher Apple (Licania michauxii), Vinca, Scarlet Sage (Salvia coccinea), and Bidens alba are all vying for attention up to a few feet off the ground. Frangipani, Jamaica Caper, 7-Year Apple (Genipa clusiifolia), Red Geiger, Bougainvillia, and Simpson's Stopper round out the list for flowering trees and shrubs.

Intensely Fragrant Genipa clusiifolia

Coral Honeysuckle and the bizarre flowers of Pipevine represent the vines. Not to  mention a few blooming Tillandsias and orchids. And this is all happening on a 60 x 110-foot lot that also holds a house, driveway and sidewalks. Apart from a few boat trips back into the mangroves, I haven't managed to get out into the natural world for several months, but things are happening there, too.

The first tiny Easstern Lubber grasshopper nymphs, which popped out of the ground in early February, have turned into adults. Birds are nesting. Osprey "chicks" have mostly fledged by now. Tropical hardwoods like gumbo limbo and mahogany are shedding their leaves in anticipation of summer's rains.

Lubber Grasshopper Nymphs. These individuals have molted several times already.

Adult Lubber. It was crawling up a screen. Don't know why I didn't sketch  that.

Monarch caterpillars are devouring milkweed faster than I can coax it to grow. Even if you can find plants in garden centers, by now they usually already have caterpillars or eggs on them. I feel like a factory worker in the old Soviet Union. As soon as he met his quota for the month, the reward was a higher quota to meet. And on and on. It's the same with the caterpillars - raise one or two successfully, and before you know it you've got multiple broods chomping down leaves and even stems. If I can't find some more milkweed, some of my caterpillars are going to starve.

I would like to use native milkweeds instead of the West Indian scarlet milkweed (Asclepius curassavica), but they just aren't available. Even my trusty native plant nurseryman hasn't had success bringing them through our hot and humid summers.

Asclepias perennis. I can't bring it through our summers.

Perhaps we butterfly gardeners are pushing the monarchs' range farther south than it should be, and encouraging them to stick around instead of migrating, but we are in the range of their cousins the queens and soldiers. The fact that both have been around for a while makes me think that there must be some native milkweed(s) surviving further inland. White twinevine  (Sarcostemma clausum) is one possibility - I've seen it growing in several locales, but it wouldn't provide a great deal of forage, so there must be others.  For some reason the queen population in my yard has crashed. I used to have swarms. Last year I had just a few, and I haven't seen any at all so far in 2018.


The downside of all the vegetative abundance in the yard is that there are far too many plants for it to be a garden. At present large parts of this small plot are virtually impassible for anything other than rodents, reptiles and birds. I hate to rip out perfectly healthy plants, but from time to time I have to harden my heart. It would be nice to have a garden again.

A Riot of Color; Not So Good for Moving Around

*Our drought has been replace by heavy rains. We've had over 9 inches in just one week here at the house, and plenty more is in the forecast. Just another way Mother Nature turns things upside down.