Scientists are advising British gardeners to forgo weedkiller this summer and instead allow certain weeds to grow, as they can provide crucial food sources for struggling honeybees. Research from the University of Sussex suggests that late summer, particularly August, is the most difficult time of year for honeybees to forage for nectar and pollen.
During this period, fewer flowers are in bloom, and increased competition from other insects means bees expend more energy for less reward. This situation can be exacerbated by heatwaves, which reduce nectar availability and disrupt flowering patterns. Species such as thistles, ragwort, and knapweed are identified by researchers as beneficial for pollinators during this challenging time.
A Difficult Season for Pollinators
Dr. Nicholas Balfour, a co-author of the study published in the journal Functional Ecology, stated that the findings highlight the difficulties pollinators face in late summer. "This is incredibly important, as this period of the year is when the vast majority of pollinator species are active and require forage to provision for their offspring," he said. The study's data, collected from nearly 1,500 honeybees and over 1,400 flowers in Brighton and Edinburgh, revealed that bee foraging is most efficient in spring when trees like horse chestnut, willow, and cherry are in bloom. Conversely, foraging success significantly drops in July and August.
Dr. Ciaran Harris, another co-author, emphasized the value of plants that bloom later in the season. "Encouraging flowers that bloom in late summer when bees find it more challenging to gather nectar or pollen will be more valuable for helping them," Dr. Harris explained. He suggested that gardeners can assist by planting late-blooming flowers, adjusting lawn mowing schedules, or tolerating weeds like thistles, ragwort, and knapweed.
The research also suggests that the challenges faced by honeybees are indicative of broader issues for other flower-visiting insects. "This means that they're a good indicator of overall availability of nectar in the landscape," Dr. Harris noted.
Professor Francis Ratnieks, also a co-author, confirmed that these findings align with previous indirect studies, including analyses of bee dances that indicated longer foraging flights in late summer. "These studies all point to late summer being the most challenging season for gathering nectar, and in doing so simplify the task of 'helping the bees,'" he stated. The consistency of these patterns across different locations suggests the late-summer food scarcity is a widespread issue in Britain.