Honey Bees Use a Clever Tool to Fight Off Giant Hornets

'Fecal spotting' is the first documented use of a tool by honey bees in nature.

Honey bees apply animal feces at the entrance of their hives.
Honey bees apply animal feces at the entrance of their hives.

Heather Mattila / Wellesley College

If you want to fend off giant hornets, it helps to have something really repulsive at your front door. 

Clever Asian honey bees (Apis cerana) use animal feces as a tool to defend their hives from giant hornet attacks. Researchers have watched the bees forage for animal dung, carry it home, and then apply it around the entrance to their nests.

Their findings, which were recently published in the journal PLOS ONE, documents the behavior for the first time.

“It turns out that by plastering animal dung around colony entrances, Asian honey bees are able to repel hornets from their nest entrances. The hornets are less likely to try to break into the colonies by landing and chewing at their entrances in a multiple-hornet attack, which is the most deadly kind of hornet attack that honey bees experience,” lead researcher Heather Mattila, Wellesley College associate professor of biological sciences, tells Treehugger.

Called “fecal spotting,” what the bees are doing is using a tool, researchers suggest.

“Tool use is a controversial topic and the criteria to identify it have been defined and redefined many times over,” Mattila says. “Across the majority of definitions, we look for an animal holding something, orienting it with intentionality, and using it is a way that improves the function of the thing that the tool was applied to. Fecal spotting by honey bees ticks all of these boxes.”

Mattila and her fellow researchers have been studying Asian honey bees and their interactions with giant hornets in Vietnam since 2013. They’ve done fieldwork in apiaries watching colonies in wooden hives managed by local beekeepers. They cleaned the front of the hives and then tracked how the bees foraged for animal feces to build up defenses against their hornet enemies.

They found that giant hornets were much less likely to land on hive entrances or chew their way into the hives when there were more fecal spots around the entrances.

“Fecal spotting works really well for deterring hornet attacks,” Mattila says. “It is amazing how well these relatively small bees can defend themselves against giant hornets, in combination with their other strategies for evading predation.”

Key to Survival

Attacks by groups of giant hornets can sometimes wipe out entire colonies of honey bees so protective measures like these are key to survival.

“This discovery contextualizes the importance of evolved defenses for honey bees,” Mattila says. “Asian honey bees have a long and impressive list of ways they fend off attacks by giant hornets.”

And this new research may have implications beyond what they discovered in Vietnam. Recently, a similar species of giant hornet (Vespa mandarinia), known as “murder hornets," was accidentally introduced to North America and may have set up colonies in Washington and British Columbia.

Because honey bees in North America already face a host of threats, adding a dangerous predator could be catastrophic. But honey bees in North America don’t have the same defenses to ward off giant hornets as Asian honey bees.

“Unfortunately, the honey bees that are kept commercially in North America and Europe have little historical exposure to hornet attacks, so that's why these colonies are so vulnerable to predation when hornet species are accidentally introduced there,” Matilla says.

Interestingly, the animal feces wards away the hornets, but the bees don't have a problem picking it up or toting it around.

"At this point, we don't know why dung repels hornets but is attractive to bees," Matilla says. "It is definitely something that needs to be investigated further."