Blueberries in bloom across Boston

The morning air carries the faint sweetness of thousands of small bells ringing. If you step outside now in late May, breathe deeply. Somewhere in the understory around Boston, lowbush blueberries (Vaccinium angustifolium) carpet the forest floor with clusters of white flowers no bigger than your pinky nail. Highbush blueberries (Vaccinium corymbosum) rise taller along wetland edges, their own pale blooms nodding from branch tips. Both species flower together in this narrow window, creating a synchronized nectar pulse across the landscape.

Each blueberry flower hangs like a tiny lantern, its corolla curved inward to protect the pollen within. The lowbush spreads in dense colonies, sometimes covering acres of sandy soil with a continuous mat of stems rarely taller than your knee. The highbush grows as individual shrubs, reaching shoulder height in the damp soil where streams meet woodlands. Both bloom now because their pollinators are active, and their pollinators are active because the flowers bloom. This circular dependency holds the entire system together.

Bumblebees work the flowers with particular skill. They grasp each bloom and vibrate their flight muscles at precisely the frequency needed to shake pollen loose from the anthers. This buzz pollination cannot be replicated by honeybees or most other insects. Mason bees and sweat bees move methodically from flower to flower, their bodies dusted with the sticky pollen. On cooler mornings when bees remain in their nests, syrphid flies and other dipterans take over, visiting flowers with less precision but equal persistence. The plants cannot afford to depend on a single pollinator species. Weather changes, populations fluctuate, emergence times shift. The network must be redundant to succeed.

This May flowering determines the entire summer. Without adequate pollination in these few weeks, the bushes produce scattered, malformed berries or none at all. The cascade effects ripple outward: fewer berries mean less fuel for migrating warblers in August, reduced winter stores for chipmunks and foxes, diminished seed dispersal for the blueberries themselves. By mid-June, successfully pollinated flowers will swell into green fruits. Through July and August, those fruits ripen to deep blue, feeding everything from thrushes preparing for migration to black bears building fat reserves for winter. The bears, particularly, serve as long-distance seed dispersers, carrying blueberry genetics across miles of forest.

Step closer to any flowering blueberry bush this week. Watch for the steady traffic of small bees, their legs heavy with pollen. Listen for the distinctive buzz as a bumblebee shakes a flower. The air itself seems to vibrate with activity, each insect contributing to a process that will feed birds and mammals for months to come. This moment of peak bloom passes quickly. In two weeks, the flowers will fade and the long work of fruit development begins. But right now, in the brief convergence of flower and pollinator, the summer's abundance hangs in the balance.