Roadside flowers may seem like a perfect place for hungry bumblebees to find food. However, new research from Sweden shows that these colorful roadside areas can become dangerous when traffic is heavy.
While flowers attract bees, busy roads increase the risk of deadly collisions with passing vehicles.
The study, led by researchers from Lund University and published in the journal Biological Conservation, explored how road verges affect bumblebee survival.
Road verges are the strips of land beside roads that often contain grass and wildflowers. These areas are becoming increasingly important because many natural habitats for pollinators have disappeared due to farming and development.
To better understand the risks, researchers examined 60 road verges across southern Sweden.
They compared roads with different levels of traffic, from quiet country roads to much busier highways. They counted both living and dead bumblebees to see how traffic influenced bee survival.
The team also used an unusual helper—a specially trained dog named Humla. Humla was trained to sniff out hidden bumblebee nests, making it much easier for researchers to find where the insects were living.
This allowed the team to study not only where bees were feeding but also where they were successfully building their homes.
The results were striking. Along the quietest roads, researchers found very few dead bumblebees. However, once traffic reached around 4,000 vehicles each day, they found more dead bumblebees than living ones.
This suggests that heavy traffic can turn flower-filled roadsides into dangerous places, even if plenty of food is available.
The researchers also found that most bumblebee nests were located beside private roads with almost no traffic or along public roads carrying only a few hundred vehicles each day. In these quieter areas, the flowers attracted many healthy bees, while deaths remained low.
The findings suggest that planting and protecting wildflowers along low-traffic roads could help support bumblebee populations. However, the researchers stress that these roadside habitats should not replace natural environments that bees depend on, such as wildflower meadows and traditional grasslands. These natural habitats remain the best places for bumblebees to feed, nest, and reproduce.
The study also highlights the need to carefully balance road management with wildlife conservation.
Across Europe, road networks cover large areas of land and could provide valuable habitats for many plants and animals if they are managed wisely. At the same time, traffic can create serious risks for insects and other wildlife.
The researchers hope their findings will help governments and road managers make better decisions about where to create flower-rich roadsides.
By focusing these efforts along quieter roads, it may be possible to give bumblebees more safe places to feed and nest while reducing the danger posed by heavy traffic.
As pollinators that help many wild plants and food crops reproduce, bumblebees play an important role in healthy ecosystems. Protecting them means not only planting more flowers, but also making sure those flowers are located where bees can use them safely.
