August nectar shortage poses critical challenge for honeybees, study finds

Honeybees face their hungriest season in late summer, and the solution might be as simple as letting the weeds grow. Researchers from the University of Sussex have discovered that August and late July represent the most difficult months for honeybees to gather nectar, a finding that emerged from the first study to directly measure the energy bees expend versus what they actually gain from foraging across an entire season.

The team conducted their work in green spaces across Brighton and Edinburgh, tracking honeybees from April through October. They observed 1,217 individual bees visiting 1,426 flowers, measuring both the time and effort each bee spent flying and walking during foraging trips and comparing that against the actual nectar they collected from different flower species. The pattern was unmistakable: late summer was the season when bees worked hardest for the least reward. Spring, by contrast, offered peak efficiency—a time when horse chestnut, willow, and cherry trees blanket the landscape in bloom, and nectar flows abundantly.

The reason for this late-summer crunch is straightforward. Fewer flowers bloom in August, and the bees that do venture out face intense competition from other pollinators, all searching for the same scarce resources. This timing matters enormously because late summer is precisely when most pollinator species are most active and most desperate to feed their offspring before winter arrives. The food shortage hits hardest when the need is greatest.

What makes this research particularly valuable is that the same patterns emerged in both cities, despite Brighton and Edinburgh being roughly 370 miles apart. This suggests the August nectar gap is not a local quirk but a widespread challenge across Britain—and likely beyond. The researchers used a novel approach, directly measuring the energetic balance of foraging rather than relying on indirect methods. Previous work in the lab had decoded bee dances to track how far they had to fly each month to find food, and those studies pointed to the same conclusion: late summer was the bottleneck.

The solution lies partly in changing how we manage our landscapes. Allowing late-summer weeds to flourish—plants like thistle, ragwort, and knapweed that typically get mowed down or sprayed—could provide critical nectar when bees need it most. Planting flowers that bloom specifically in late summer offers another avenue. Adjusting mowing schedules to let these plants flower unmolested could make a real difference. The researchers emphasize that this is not merely an aesthetic choice but a practical intervention with measurable consequences for bee survival.

The urgency has only grown. Heat waves are already disrupting flowering times and reducing nectar availability in flowers, layering additional stress onto bees already struggling with agricultural intensification and habitat loss. In years when climate volatility is high, the presence of late-blooming weeds and flowers becomes not a luxury but a buffer against collapse.

The findings extend beyond honeybees. Because honeybees visit such a wide variety of flower species, they serve as a reliable indicator of overall nectar availability in any given landscape. If honeybees are struggling, other flower-visiting insects likely are too. The researchers acknowledge that their study examined only two locations, leaving open questions about how different land-use patterns—gardens, farmland under conservation schemes, urban parks—might fill or worsen nectar gaps throughout the year. Follow-up work will be needed to map these patterns and understand how landscape management choices ripple through the seasons. For now, the message is clear: late summer is when bees need us most, and the simplest help may be to stop fighting the weeds.