I’m kneeling quietly, staying as still as possible, before a mass of luxuriant white flowers at the edge of a gorge in a distant, hidden corner in the highlands of Kenya. It is 5.45 a.m. Sunrise is still some thirty-seven minutes away. The eastern edges of the horizon are laced with saffron and drunken crickets rasp intermittently. Larks and robin-chats start warming up and in the distance is the forlorn, territorial sawing of a lonely leopard.
A furtive and whirring sighing rustles through the cool, crisp air. Swiftly it moves amid the shadows, more heard than seen, a blurred suggestion of form in the blue-grey stillness before dawn. Then ever so stealthily, with proboscis unfurled, she probes the heart of her unsuspecting, but patient, evolutionary match and is rewarded with a millilitre’s measure of nectar. A cute floral nod and it’s all over. Millions of years of evolution reduced to just a millisecond of mutual pleasure and benefit.
And like all naturalists who have borne witness to nature’s myriad mysteries many times before, I have come to learn and have been blessed with a small discovery.
For the past ten years, I have been studying the intimate interactions between hawkmoths and the flowers they pollinate. Hawkmoths, also known as sphinx moths, are an intriguing and incredible group of insects. They are fast-flying, long-lived and feed actively from many different kinds of flowers, a fair number of which they alone can pollinate. Despite their relatively high diversity, little is known about their actual role as pollinators and in particular as specialised pollinators of highly adapted plants, though it is widely estimated that about 10 per cent of all tropical flowering plant species are pollinated by hawkmoths. Among naturalists, they are known as the quintessential phantoms of the dusk because they emerge, to approach flowers, just as darkness gathers. After hundreds of hours spent waiting to see them, and many thousands of fleeting glimpses of these enigmatic creatures, I’ve learned to avoid looking for them on cold or misty mornings, to stay still, to move slowly and to watch very, very closely, as their flower feeds can last less than a few seconds.
I grew up in Eldoret, a small, sleepy and rural town in western Kenya, and some of my earliest memories are of watching insects. As a child who suffered from the trauma of a broken home, I found refuge in nature. Later on, my love of insects connected me with the most wonderful foster parents who had come to Eldoret to help establish a new teaching hospital and training programme for Kenyan doctors. Along the way, our lives came together. My foster mother always says we ‘met through a moth’. I had been raising giant moths, which all hatched out and fluttered about the day she first visited me at home. Caring for the caterpillars had provided many hours of joy, and had kept me focused and away from thinking too much about what was happening at home, and when they hatched, we were both enchanted. My late mother, my foster parents and many wonderful teachers encouraged, nurtured and indulged my love of natural history, and after finishing school, I won a scholarship to Indiana University. Routine class and campus life, however, was not my cup of tea, but – thanks to some sympathetic professors – I was able to spend time in the Amazon rainforest and the wilds of Kenya, working on independent study and earning a degree in anthropology and biology.
Having finished my degree, I returned to Kenya, determined to use my training to make a difference in the field of conservation, and to understand more about the incredible natural resources that Kenya is blessed with. My work saw me writing, drawing and exploring different parts of the country, learning from insects and plants and sharing these lessons where I could. But after a few years of feeling beaten down by a corrupt culture of patronage, and finding that it was increasingly difficult to get a footing in conservation without the necessary ‘connections’, I wanted to give up. In addition to these disappointments, I realised that no one really paid much attention to insects, in Kenya or anywhere else, and in conservation circles, most of the funding and attention went to those working on big ‘charismatic’ animals. Once again the wisdom of my foster parents prevailed. ‘Do what you love,’ they said. And I did. I undertook my master’s degree with a world expert in pollination at the University of KwaZulu-Natal. This allowed me to continue making the kinds of observations about plants and insects that I had loved as a child, and to forge a scientific career with the foundations I had in natural history. After my master’s I spent a few years working as a freelance writer, helping out on research projects, falling in love and making all sorts of mistakes, and then, to my utter amazement, I won a scholarship to Harvard University, where I completed my PhD, looking at the evolution of cooperation and interactions between plants and insects on the African savannah.
My journey to this particular moment of discovery on the edge of a gorge in the Kenyan highlands had, in fact, begun the night before.
On an evening walk with the dogs, I had followed a sweet, musky perfume towards the edge of the gorge. Suddenly, the fragrant dusk is filled with sounds and shadows. Crickets, strumming their wings, utter chirps and whistles. A high-pitched silvery squeak, barely within the range of human hearing, punctuates the erratic course of a bat overhead. Leaves rustle and branches creak as gentle gusts of breeze move through the forest. Pinpoints of light – courting fireflies – flash in the damp depths.
The fragrance grows more powerful with each passing minute and, clustered close in the gnarled arms of a dying tree, a spray of white stars, is the source of the delicious scent.
The white stars, softly bright against the dark mottled tree trunk, are orchid flowers: the comet orchid (Rangaeris amaniensis), a widespread and abundant species found throughout the highland forests of East Africa. Each flower, crisp and pure white, is a fantastic, marvellous sexual structure.
As with all orchids, three petals and three sepals are arranged to form the flower. One of the petals – the ‘lip’ of the orchid – is larger and more complicated than the others and sits between the two lower sepals, pointed and curved, completing the symmetry of the star.
Projecting from behind the orchid’s lip is a long, tubular and tapering spur which contains a precious store of nectar. The spur itself is six inches long and the nectar level, measured from the bottom end of the spur, comes up to barely half the spur’s length. This means that whatever visits this flower – whatever sips the nectar and hopefully transports the pollen – must be able to reach down at least four inches into it with a proboscis, a long, narrow tongue.
In the final moments of dusk, when the far western skies are a pale line of fading burnt sienna, a whirring of wings rustles the air above the flowering orchid and, lured closer by the sweet, heady scent, homes in on the white flowers. This is the convolvulus hawkmoth.
With its attenuated tongue uncoiled and dangling, quivering, the convolvulus hawkmoth hovers in front of the spray of orchids. It probes gently with its extended proboscis and, guided by the symmetrical shape, it reaches effortlessly into the orchid. Its tongue travels down into the spur, drawing the hawkmoth itself closer and closer to the flower. As the tip of its proboscis finds the nectar it drinks deeply.
As the nectar level falls from being swiftly sucked out, the hawkmoth presses itself against the flower. Now the base of its proboscis rubs against a special structure hidden just inside the middle of the flower. Here, waiting patiently, are two pollen masses, known as pollinia, with sticky strands attached to them. The mechanism works perfectly. As the base of the hawkmoth’s proboscis presses against the inside of the flower, the pressure forces the sticky strands onto the hawkmoth’s tongue.
With no more nectar within reach, the hawkmoth pulls away and in so doing brushes up against a sticky strand, known as a viscidium, which holds fast to its proboscis and pulls out the bundle of pollen. The moth hovers backwards, perhaps surprised by the unexpected addition to its long tongue. The pollen masses of the orchid are now firmly fastened to its tongue.
The convolvulus hawkmoth probes two more open flowers, then, startled by a flitting bat overhead, swiftly flies off deep into the forest bearing the orchid’s genes with it. This brief and remarkable incident represents an ancient evolutionary relationship between hawkmoth and orchid, successfully played out over millennia in short, three-second acts, time and time again.
Insects and flowers have been intimately involved for hundreds of millions of years. Much of the food that we eat, and much of the food that we most enjoy, is a result of their synergy. ‘One in three bites of food is thanks to a pollinator’ is an oft-quoted refrain today, and some 80 per cent of flowering plants rely on pollinators to reproduce and survive. Without them and their symbiosis, our world would be unimaginably poorer.
Insects almost everywhere in our fragile world are under threat. Bees, butterflies and other pollinators are disappearing at unprecedented rates, in many cases before we even fully understand how important they are. Most research has been done in temperate, highly industrialised countries of Europe and North America, but most of the earth’s diversity is located in the tropics, and relatively few scientific lifetimes have been dedicated to understanding the vast, complex web of life still here.
Sadly, now even the remote reaches of wild Africa are being tainted by poisons designed to kill insects, spread through global trade and the growth of intensive agriculture. For many decades, rural farming systems across East Africa had been relatively free of toxic pesticides, but in recent years access and use have been increasing. While managing pests is important, and farmers should have access to agricultural inputs and technology, how, where and when these are used do matter. One of the most alarming trends is the dumping across Africa of highly toxic pesticides that have been banned elsewhere, but are shipped and ‘donated’ to unsuspecting farmers and government agencies across the continent. Exact data is hard to come by, given the skulking, shady deals that make up these transactions, but the UN estimates that many tens of thousands of tonnes of chemical pesticides are being disposed of in the region.
Anyone who slurps down coffee or nibbles on chocolate needs to be grateful to insect pollinators.