Primroses and Peaches

What do primroses and peaches have in common? There are many answers, I suppose, like being plants, starting with the letter P, having flowers, etc. One commonality is that they both occur in my garden. Another is that they are both friends of a moth.

The particular moth happens to be substantial. It is tawny with a blush of pink across the hind wings and delineated with narrow white scales throughout. And it is big – as big as a hummingbird. In fact, it is sometimes called a hummingbird moth. More specifically it is known as the white-lined sphinx (Hyles lineata). In my garden, it likes both primroses and peaches because both plants produce nectar right when it wakes up in the spring.

Unlike a hummingbird, though, the white-lined sphinx flies at night, becoming active just as the sun is setting. This is really good timing as far as the primrose is concerned. It opens its flowers at the same time. They are big white flowers and full of sugary nectar that collects at the base of the petals.

Primroses and hummingbird moths have been interacting for millions of years. Just how closely is a bit of a guess; but part of the story is beginning to be worked out by a group of scientists working in Israel. One of their more interesting discoveries is that primroses can detect when hummingbird moths are flying nearby. The sound of beating wings stimulates the plants to produce more nectar. Within three minutes of arriving at a flower, there is an uptick in sugary water in the nectaries (Veits et al., 2019). This makes perfect sense for a flower. Why spend the energy and resources to attract pollinators that aren’t even there?

If you pay attention to the way hummingbird moths fly around flowers, you can see how the moths have evolved to work with this potential inconvenience. They don’t spend all of their time at one flower waiting for the three minutes in order to collect their reward. Like hummingbirds, they flit from flower to flower looking (and smelling) for nectar. In effect, they buzz announce themselves to several flowers all at once, thus stimulating nectar production across an entire swath of meadow.

Earlier in the year, just as the peach blossoms were opening in our garden, I watched a white-lined sphinx move from flower to flower in our meadow of primroses. Then it made a detour to visit several peach flowers and then quickly flew back to the primroses. These moths fly fast, and the whole thing was over in just seconds. At first, I didn’t understand the significance of what I had just witnessed. And then it occurred to me: my peaches were being pollinated by something other than a honeybee. They were being pollinated by a native insect.

Now I have nothing against honeybees. Some of my professional colleagues call them invasive pests since they compete with our native insect pollinators. Our own bees and butterflies would be better off, they say, if honeybees had never been introduced to the Americas. My own perspective is a bit more nuanced.

A lot of the fruits and vegetables that we enjoy need to be pollinated in order to set fruit. And while it is true that many native bees can do this work just fine (like members of the genera Bombus and Osmia, among others) many plants blossom too early in the year when native pollinators have not yet emerged from hibernation. Honeybees, on the other hand, that are active early on, are able to pollinate these early bloomers just fine.

I live in a state that reveres the hard work and helpfulness of honeybees. It is part of our pioneer culture. The establishment of farms, ranches, and orchards over the last century and a half – including the challenges of moving and collecting bees across hundreds of miles of wilderness – is a remarkable tale that is hardly recognized anymore. We certainly owe a lot to our agronomist ancestors and the foreign insects that they nurtured.

But honeybees are vulnerable these days. As are many of the native pollinators with whom they compete. Both are struggling to maintain their health even as they service the struggling ecosystems in which they live, and upon which we depend. And so I got a little excited to see one of our native moths on a tree that produces food.

There is more here, however, than an orchard with insects and flowers. There is also a fable. There is something about the limits of human nature in the flight of the hummingbird moth that slowly worked its way into my awareness as I sat on my garden chair early in the spring.

The primrose and the white-lined sphinx are both native to Southern Utah. Scientists call their relationship a mutualism. The moth both feeds on the leaves of the plant in its larval state and on the nectar of its flowers as an adult. The plant, in turn, gets pollinated in a very specific way and time by the insect and is able to produce seeds and propagate.

These kinds of natural relationships are key to the health of both species. Neither one of them needs peaches, nor do they need the humans that plant and eat peaches. And we humans do not depend on these species either, at least it appears that we don’t. But here the relationships are not so clear cut.  

It is obvious that most peach orchards around the world do very well without either primroses or hummingbird moths. But there are no peach orchards – or any orchards, for that matter – that exist without the products of healthy ecosystems. And primroses and sphinx moths are little pieces of these ecosystems.

To farm without native pollinators is an act of human ingenuity that is both novel and in need of continued human artifice. It is also extractive of the natural world in that it displaces native habitats for the creation of farmland itself and for the resources that both fertilize the crops and poison the pests. In a word, this is not a sustainable form of farming.

But to farm with primroses and hummingbird moths is a different kind of relationship. And it can teach us a few simple yet important things about how humans might intervene if we presume to do so. As a fable, it might follow something like this.

A long time ago there lived alone on a distant island many primroses and sphinx moths. It was a pleasant island. There was plenty of sunshine and rain and the primroses grew and reproduced abundantly year after year.

The sphinx moths lived bounteously as well. They ate the primrose leaves as young caterpillars and when they spun their cocoons and became large full-bodied moths, they visited the night-blooming flowers of the primroses and spread their pollen to other primroses. The pollen helped the flowers set seeds to make other primroses. 

The cycle continued season after season and year after year. Then one day a peach seed landed on the island in the tangled branches of a floating log and after months of rain, it sprouted and began to grow.

The peach seedling matured into a beautiful tree full of long slender leaves, the only tree on the island. And in the spring, it’s buds opened into delicate pink blossoms. At first the sphinx moths paid no attention. They would never lay their eggs on the tree because the caterpillars could not eat the leaves. But one day a single moth landed on the peach tree in the spring and noticed that the blossoms smelled appealing. It was a different smell than the primroses, but attractive, nonetheless.

The moth decided to taste the nectar of the peach blossoms and found that it was very satisfying. Soon other sphinx moths did the same. They would feed on the primrose flowers and then fly happily over to the peach tree and sip a bit of its lovely nectar as well.

For many years, all three species lived together in contentment on the happy island. But as the years passed, other peach trees began to grow, thanks to the many pollinating visits of the sphinx moths. At first this was a nice development. The little island now had beautiful primroses flowering along the ground and the pleasant canopies of peach trees to offer shade.

The sphinx moths continued to enjoy the nectar of both the primroses and the peaches and assumed that there would always be primrose leaves to feed their caterpillars. But as the years passed and more peach trees grew, there were fewer and fewer places for the primroses. In many places the sunlight never reached the ground where they were growing.

Sadly, the primroses all disappeared and only the sphinx moths and the peach trees were left. But when the time came for the mother moths to lay their eggs, there was no place available. They flew all over the island looking for primrose leaves but never found a single plant.

So instead the moths laid their eggs on peach leaves. But in the spring when the eggs hatched and the baby caterpillars began to eat the leaves, they got sick and couldn’t grow. Those baby caterpillars never became adult sphinx moths and never visited the flowers of the peach trees.

Soon the moths were all gone as well, and only peach trees remained. But when the moths disappeared there was nothing left to pollinate the peach flowers. After many years the first peach tree got old and died. Then branches began to fall from the other trees too. Eventually there were no living trees left on the island, only the stumps of where they once grew. The island became a baren place that seabirds avoided, and the surf pommeled relentlessly.

This is a sad story. Maybe there is a silver lining. Maybe there is a steep cliff on one side of the island where primroses and sphinx moths remain. Maybe we could modify the ending so that a few humans arrive and garden all three species in a truly sustainable way. Fortunately the sad story doesn’t represent the reality of my garden. Part of the reason is that peach trees don’t grow spontaneously in southern Utah. They need a particular kind of tender loving care. But I do love eating peaches and the sight of the spring sphinx moth made me anticipate a later harvest, even as I admired my native primroses with their flowers made up of heart-shaped petals.

What also came to mind was an almost forgotten chapter in an old book that I read many years ago. The author was once a well-known political economist by the name of Frederich Hayek. The chapter I remembered reading was, Why I Am Not a Conservative. And in the last sentence of this last chapter Hayek wrote, “I doubt whether there can be such a thing as a conservative political philosophy. Conservatism may often be a useful practical maxim, but it does not give us any guiding principle which can influence long-range developments.”

This was a pessimistic statement for Hayek because he was conservative at heart. He was essentially saying that liberals had made too many mistakes to be taken seriously and that conservatives had no right to pretend that they could do any better.

But years after I read Hayek’s pessimistic indictment, I happened to read another chapter in another book. The author this time was Wendell Berry and the chapter was titled, The Way of Ignorance (in the book by the same name). Berry doesn’t fit neatly into any political category, liberal or conservative. He is both and neither, depending on the issue at hand. But his essay is kind of an answer to Hayek (although the older author is not mentioned).

For Berry, the correct way to muddle forward, given the poor track record of all political parties, is to acknowledge our ignorance even as we succeed in our many technological triumphs. To rush forward with novel ideas and products in a world that is now so connected and beyond anyone’s ability to navigate properly, is to invite disasters of global dimensions. Instead, Berry argues, we should keep what works and adopt novelties with caution, and when needed. Conservativism should mean just that: conserve what is working even as we seek to improve what needs improvement, always looking to the future with wisdom and with the past in mind.

Such thoughts might seem odd, prompted as they are from a sphinx moth on a spring morning in a southwestern desert. But sometimes thoughts just come unbidden. And in those few seconds of observation I learned something else. The grower himself (that would be me) can make all the difference, especially if (s)he happens to care about both the primroses and the peach trees. Gardening with native plants and insects as well as with conventional crops might seem forced, perhaps like a poorly designed collage. On the contrary, I have found it to be both fascinating and beautiful. In fact I can state with authority that this gardener even cares about the sphinx moth. And, if by misfortune we lose our honeybees, maybe I can still enjoy my peaches.

I think it matters that we pay attention to the wisdom of the insect, that is: keep the old relationships with Earth healthy and as our first priority even as we consider the novelties that our reconstructed world demands. I, for one, intend to do just that.

References

Berry, Wendell. (2005). The Way of Ignorance, and other Essays. Shoemaker & Hoard.

Hayek, F.A. (1960). The Constitution of Liberty. The University of Chicago Press.

Veits, M., Khait, I., Obolski, U., Zinger, E., Boonman, A., Goldshtein, A., ... & Hadany, L. (2019). Flowers respond to pollinator sound within minutes by increasing nectar sugar concentration. Ecology letters, 22(9), 1483-1492.

von Arx, M., Sullivan, K. A., & Raguso, R. A. (2013). Dual fitness benefits of post-mating sugar meals for female hawkmoths (Hyles lineata). Journal of insect physiology, 59(4), 458-465.