“Forceps,” I called, and Therese placed the metal tool in my outstretched hand. I pinched the sharp ends together and lowered it into the narrow opening, keeping my eyes trained on the dimly lit object within. Slowly, surgically, I made contact with the leaf capsule and pulled it out of the six-inch-long dirt tunnel.
I am no surgeon, though I was in school a long time. I am a melittologist, an investigator of wild, solitary, nonhoneybees, and I’ve been collecting bees since I was a girl, fascinated by their delicate wings and fuzzy, articulated bodies. Today, this lifelong pursuit has brought me to the rocky summit of Pinnacles National Park, one of America’s newest parks and a global hot spot of bee biodiversity. Looking out over central California’s vineyards to the east and Monterey Bay to our west, my field tech, Therese, and I knelt, sweating in the midday sun, carefully excavating a subterranean bee nest. In a world frantic over honeybee decline, relatively little is known about thousands of species of ground-nesting bees, nature’s premier wild pollinating fleet.
We had been hiking this trail every two weeks. The route is steep, rocky, and exposed, an hour of power walking from our park housing below. Just before the trail descends back down the eastern ridgeline, there is a large blue oak whose branches arch daringly over the precipice that drops into Condor Canyon. Adorning its roots, tan breccia rock shards, relics of the long-inactive volcano that once shook these hills, cling tenuously to the bare hillside. We were taking a break in the shade of this tree when we first saw her zoom past and disappear into the earth. She clutched a freshly cut leaf crescent: the beginnings of a bee nursery.
We shouldered our gear and slid out from the shade to perch among the scattered stone and prickly, invasive grasses. We moved slowly, as if we could hide from a bee. As if we should. Crouched in silence, we scanned the ground for her tiny nest entrance — just the width of a pencil eraser. Turkey vultures circled while we watched for micromovement. In full sun and triple-digit heat, we sat, and sweated, and awaited her next move.
When she failed to reemerge, we marked the spot with a rock cairn and moved on. We had miles to walk and more bees to find. I recorded her as a member of the leaf-cutter genus, Trachusa, known for crafting tiny leaf capsules for their offspring and stacking them into drinking straw–shaped nests dug into semiarid hillsides exactly like this one. She would be one of many leaf-cutter species, as yet unknown, all with their own nesting style and leaf preference, discoverable only by methodically digging them up.
In the hills beyond, we found metallic-blue mason bees using mud as nest mortar, velvet-faced mining bees tunneling homes into sandy soils, bright yellow wool-carder bees cradling their eggs in fibers scraped from leaves, as well as wood-excavating carpenter bees, gregarious bumblebees, tiny yellow-faced bees, innocuous sweat bees, inimical cuckoo bees, and many species yet to be named. For reasons not fully understood, Pinnacles’ rolling meadows, riparian woodlands, and gravelly canyons are home to more species of bees than any other place its size. We were there to catch them all.
While the world worries about honeybees, originally imported from Europe, baseline data on bee species native to the U.S. are in shorter supply, though they may hold the key to understanding pollinator health. Nearly all reproduction of wild plants is aided by nonhoneybees. Wild, native bees also pollinate domestic crops. But unlike tamed honeybees, scientists can’t keep them alive for study in a box in a lab. Their diminutive size, loner habits, and brief life spans have helped the land keep their secrets, and research on wild pollinators has been slow to progress.
Two weeks after our first sighting, we found our Trachusa peering from her nest entrance. We watched her depart on a foraging flight and return twenty minutes later, her underbelly packed with bright yellow pollen. She would not live long enough to meet her offspring, so, like a Santa bee at work while the next generation sleeps, she stocked the nest with the nutrients they’d need to grow and survive winter. A fortnight later, we found her busy dragging pebbles and grass into place, concealing all evidence of her life’s work. On our final visit, we knew she’d be gone, collapsed from exhaustion or work-shredded wings. After a moment of reverence, we laid out our tools to unveil her craftsmanship. Inside the nest we found five tiny leaf capsules, each encasing one developing larva: the bees of next spring. Closest to the surface were the males, fastest to develop and first to emerge. In lower cells, the females, laid first, grow larger and must crawl farther to the surface. My heart pounded as I unearthed the last leaf capsule. Piece by desiccated piece, I unwrapped it like a present. And there in my hand were the ingredients for a bee.
Our hope is that by understanding how and where native bees build their nests, we will be better equipped to aid their conservation. Over the next two years, Therese and I documented 354 bee species. But the bees of Pinnacles are more than the sum of their parts. Together, they are responsible for weaving a rich tapestry of wildflower landscapes across the blue oak highlands, live oak lowlands, rocky canyons, and amber, wavy grasslands that make up the fabric of this diverse natural area. O