- There are over 20,000 species of bees in the world. Most of them are solitary bees that do not live in hives and do not make any honey.
- Solitary bees live solo and forage and fend for themselves. The availability of nesting sites are key to the survival of these species.
- As bees are important pollinators and increasing nesting sites for solitary bees around farms where crops like chilies, bell peppers, and tomatoes are grown, is known to be beneficial.
One morning in April 2020, early in the lockdown during the COVID-19 pandemic, I leaned over the terrace parapet of my home in Bengaluru, scanning the spreading branches of a Yekke (aak; aakdo; Calotropis gigantea) plant to spot a pale-billed flowerpecker whose trills I could distinctly hear. Eye to the viewfinder, I looked for the bird, the smallest in India at just over 3 inches.
I found something else entirely. A dark form, an obsidian body with sky-blue eyes, was perched on a flower, its head bent into the petals. Hastily focusing on it, I shot off a few frames as it shifted on the flower, on its hairy legs, piercing the base of each petal in turn and sucked nectar. Drawing back from the edge of the parapet, I squinted at the LCD display of my camera. The shifting iridescence — blue, purple, green, ochre — in its wings was stunning. Later that day, I posted the photo to Twitter, mistakenly calling the wondrous creature a bumblebee.
“It’s a carpenter bee,” a wildlife biologist corrected me. “The only bumblebees in India are found in the Himalayas.” Thus started my journey into a fascinating, lesser-known world — the world of the carpenter bee, of the genus Xylocopa.
One of the best-kept secrets of the bee-world is this: of the 20,400 species of bees in the world, over 90% do not live in hives and do not make any honey. That percentage shoots up in India, where of the 700 or so bee species, only five are social bees, living in hives and making honey. The rest are “solitary” bees — there is no “queen bee” or “workers,” no social hierarchy. These bees live solo and forage and fend for themselves. Moreover, they play an important role in our world. Solitary bees are crucial to the pollination success of several crops like cucurbits, blueberry, cranberry, tomatoes, eggplants, apples, plums, almonds, and all manner of lentils, among others.
Bees have always found a special place in the human imagination. Bhramari in Hindu mythology is a bee-goddess, an incarnation of Goddess Parvati, the consort of Lord Shiva. Legend has it that Parvati commands all the bees, wasps, and flies of the world which cling to her body, and she assumes the avatar of Bhramari in battle against the demon Arunasura. The demon, invincible by way of boons received in penance, is nevertheless vanquished when hordes of bees and wasps leave Bhramari’s body at her command and attack him. The big, black, shiny carpenter bee, “bhramara,” appears often in Sanskrit poetry, usually hovering around young maidens, as a symbol of lovesick men.
Suzanne Batra, in her 1993 paper “India’s Buzzy Biodiversity of Bees” recounts other mentions of carpenter bees in history and mythology. These big bees were apparently used to carry messages tied to their thorax, much like passenger pigeons were employed in days of yore.
Hema Somanathan, at IISER Trivandrum, who researches solitary bee behavior, concurs. “Carpenter bees are indeed great at trap-lining — a method in which individual bees follow set routes to forage for food,” she says. “They know and recognise plants and flowers and can (and do) find their way to the same area, flying the same route repeatedly. It is thus conceivable that these large bees could have been used to carry messages along a route.”
Bees in the backyard
Except for one introduced social honeybee species — Apis mellifera — all the bees found in India (solitary and social) are native bees. And of the native solitary bees, the one I’d just seen foraging was the largest: the female Xylocopa latipes.
Thoroughly intrigued, I began to look out for bees in my overgrown, wild urban garden in which I had tried to plant mostly native flowering plants. At least four species of carpenter bees came each day, and several other species of solitary bees occasionally. Signs were everywhere. Leaves neatly sculpted and carved out meant leaf-cutter bees had been at work. Eyes staring from thin hollow sticks and wall crevices meant mason bees roosting. Bees with abdomens banded blue and green, some black and yellow, others polka-dotted blue and black were everywhere, once I started looking.
Only two of the many species of bees in my garden turned out to be honeybees. They bookended the size spectrum of honeybees found in India: the largest, the giant Indian honey bee or rock bee, Apis dorsata, and the smallest, the dwarf bee, Apis florea. Peering into the foliage turned up a dwarf-bee hive in an overgrown creeper, from which these tiny bees foray out to forage for nectar and pollen on petrea flowers, moringa flowers, and in a nearby patch of basil.
All the other bees in the garden were solitary bees.
Each morning, as the summer sun came up, the carpenter bees would appear. They followed a pattern — one species (usually the fluffy yellow Xylocopa pubescens) would be the first to arrive, the male leading the way. The taxicab-like female, sporting a yellow thorax and black abdomen, would follow. As the morning droned on, other species would zoom in from various directions.
The last to come, announcing her arrival from afar with a loud buzz of wings beating at over 100 times a second, carrying a veritable little weather system of swirling air along with her, would be the massive Xylocopa latipes — among the largest bees in the world.
Oftentimes, she’d have her legs or the underside of her abdomen covered in yellow pollen. This is what she was collecting, along with nectar, and unwittingly depositing, thus assisting in pollination. She was provisioning for her next generation.
Female carpenter bees carry the nectar in their bellies, and pollen on their legs and on the undersides of their abdomen, back to their chosen cavity. This female would forage, flying from flower to flower, then belly-full, she’d zoom away eastwards, over and beyond the community wall. There was no way I could follow her and find out where she nested.
Once at her cavity, which, like that of most carpenter bees, could be a bamboo pole or any wooden crevice or burrow, she’d regurgitate the nectar and mix it with pollen to fashion “bee-bread,” food high in protein and calories. This she will deposit in a chamber, lay a single egg, and seal it. Then she’d move on to the next chamber — chambers are built upon chambers, apartment-style, and repeat.
These bees do something very interesting with the topmost chamber in their nest. The egg they lay in that chamber hatches male. This male pushes out of the topmost chamber and prepares to mate with other females. How mother bees engineer this is still not very well understood.
The bee-bread serves as food for the new larva that will emerge, eat, pupate, and itself emerge as a bee, make its way out of the chamber to mate, provision, and carry on the lineage. Mother would likely never meet the offspring. These species are truly “solitary.”
Females of solitary bees (Megachilids) like these mason bees nest in crevices and tiny holes — hollow stems, bamboo, even pipes. Of the 20,400 species of bees in the world, 
A Xylocopa carves a hole in a bamboo. Carpenter bees, as their name suggests, carve holes into wood or bamboo with their powerful mandibles. Lack of nesting sites is a threat to the survivial of solitary bees. Photo by Arati Kumar-Rao.