"Do 'Drunken Wasps' Really Become Aggressive? Unraveling the Scientific Reasons They Swarm Around Beer"

On a summer afternoon, while enjoying a chilled beer on a terrace or in a beer garden, small yellow and black visitors appear from nowhere.

Even if you shoo them away once, they come back again.

They fly around the rim of the glass, trying to land on the foam. If there are dishes lined up, they then approach the meat or desserts.

Seeing such behavior,

some might wonder, "Do the bees also want to drink beer?"

"I've heard they become aggressive when drunk."

In fact, on the internet, there have long been theories that "bees at the end of summer get drunk by eating fermented fruits" and "bees that have consumed alcohol become aggressive."

However, recent research shows that the story is not that simple.

At least some hornets might have an incredible tolerance to alcohol from a human perspective.

Hornets that can function even with 80% alcohol: "Heavy drinkers"

This image was significantly changed by research published in the scientific journal PNAS in 2024.

The subject of the research was social wasps known as oriental hornets.

The research team added various concentrations of ethanol to food containing sugar and examined the wasps' survival and behavior.

Surprisingly, these hornets showed no significant long-term survival or normal activity impairment even when consuming very high concentrations of alcohol.

In experiments, ethanol concentrations as high as 80% were tested, which is incomparable to regular beer or wine.

For humans, even consuming such a level as a drink is dangerous.

Yet, the hornets studied showed remarkable tolerance, at least under experimental conditions.

The focus is on their mechanism for breaking down alcohol.

The research showed that the Vespa genus, including oriental hornets, has multiple copies of genes related to alcohol metabolism.

This suggests that ethanol might not be merely a toxin for them.

In nature, ripe or damaged fruits can ferment due to microorganisms. It is believed that adapting to such environments over a long time has resulted in their high alcohol processing ability.

However, there is an important caveat here.

This result is from research on specific oriental hornets and does not mean "all bees worldwide can handle 80% alcohol without issue."

Physiological functions differ by species.

Therefore, generalizing that "since it was confirmed in hornets, it must be the same for all paper wasps and hornets in Japan or Europe" is dangerous.

Why do bees approach beer?

Do bees fly to beer thinking they want to "get drunk"?

From a human perspective, seeing insects approach beer makes one think, "They must like alcohol."

However, it is believed that the "smell of fermentation" is more important than the alcohol itself.

A study published in 2014 on paper wasps showed that they are attracted to smells derived from fermentation, such as wine.

In nature, when fruits ripen and begin to ferment, various volatile substances are released.

For bees, that smell can signal "there is high-calorie food nearby."

Thus, chasing fermentation odors has had survival benefits long before humans invented beer.

Beer and wine coincidentally emit scents similar to those natural food signals.

From a bee's perspective,

it might not be "there's alcohol here,"

but rather,

"there seems to be food rich in sugars around here."

Especially with strongly scented beers, various fermentation-derived components are released.

Therefore, the "beer-like aroma" we perceive might serve as a clue for insects in their food search.

The main attraction is not beer but "sugar"

The primary reason summer bees come to the table is ultimately food.

Worker bees need energy to function, and an essential source of that energy is sugar.

Juice, ice cream, cake, ripe fruits, soft drinks.

These are very attractive to bees.

On the other hand, during summer, they may also show strong interest in meat.

This is not because they want to enjoy steak themselves.

Social bees need protein to feed the larvae growing in the nest.

Therefore, when eating meat dishes outdoors, worker bees might nibble on the surface and try to carry small meat pieces back to the nest.

From a bee's perspective, a human dining table looks like a massive buffet with sugars and proteins all in one place.

Even if you clear away the beer, if sausages or cakes remain, they will return for other reasons.

"Persistent" and "aggressive" are different

Here, too, there is a significant gap in perception between humans and bees.

Seeing bees returning repeatedly after being shooed away, humans tend to feel "they're angry" or "they're targeting me."

However, the purpose of bees around the table is often not to attack but to search for food.

The German nature conservation organization NABU also explains that bees searching for food away from the nest are not approaching to attack humans.

The problem arises when humans, out of fear, wave their hands vigorously or try to swat them.

From a bee's perspective, a giant object suddenly approaches at high speed.

If they judge that they might be caught or crushed, the likelihood of stinging as a defensive action increases.

"Did the bee attack because I waved my hand, or did I wave my hand because the bee attacked?"

At the scene, this sequence might be perceived in reverse.

Why do bees suddenly increase at the end of summer?

"In August, bees suddenly become persistent."

Many people have this impression.

There are ecological reasons for this too.

From summer to late summer, the seasonal cycle progresses in social bee nests.

Changes in the number of larvae and the state of the nest affect the foraging behavior of worker bees.

According to NABU, from late summer to autumn, worker bees have more opportunities to search for sugars and proteins outside the nest and frequently appear at human tables.

In other words,

it's not a simple story of "bees become ill-tempered at the end of summer because they drink."

Rather,

it's more natural to think that "the circumstances of food searching change with the seasons, increasing contact with human meals."

As the number of contacts increases, naturally, troubles also increase.

As a result, the impression that "bees are aggressive in this season" might be reinforced.

On social media, reports of "seeing drunk bees" are widespread

Meanwhile, a search on social media reveals many anecdotes of "bees that seemed actually drunk."

On the overseas forum Reddit, there are posts about bees that ate fallen fruits in the garden,

describing experiences like "they were flying unsteadily"

and "they couldn't fly well even when trying to take off."

A user who temporarily trapped a bee in a glass at a brewery recalled that after drinking the remaining beer droplets, the bee seemed unable to keep its body straight.

Another thread introduced the practical wisdom of using a coaster to cover glasses in German beer gardens to prevent bees from entering.

"They really flock to the smell of beer."

"Several flew into the glass within minutes."

Such voices are also present.

Furthermore, as is typical on social media,

there are humorous reactions like "drunk bees are like a horror movie"

and "maybe they're just having a drink after work."

It's interesting that while bees are a nuisance to humans, a culture of anthropomorphizing them as wanting a drink has emerged.

Do social media sightings contradict scientific research?

 

This raises a question.

However, there are reports on social media of "bees that couldn't fly because they were drunk."

Which is correct?

The answer is, "both are possible."

First, the term "bee" encompasses a vast number of species.

Just because one species has high alcohol tolerance doesn't mean another species will be the same.

Furthermore, in social media sightings, it's impossible to confirm if the insect's abnormal behavior was truly due to alcohol.

Temperature, fatigue, weakness, pesticides, or injuries could also cause erratic flight.

Moreover, humans tend to interpret animal behavior in human-like terms.

Seeing a bee sway side to side makes one think "it's drunk," and if it returns repeatedly, it feels like "it's coming back drunk and pestering me."

While social media anecdotes are interesting observational records, they don't constitute scientific proof.

Conversely, results obtained from experiments on one type of bee in a lab cannot explain the behavior of all wild bees worldwide.

It's necessary to consider these two separately.

Is "becoming aggressive due to alcohol" proven?

This is probably the most intriguing point.

Do drunk bees really become aggressive?

At least from the research referenced here,

there is no simple causal relationship that "bees lose judgment like humans when drinking and become quick to fight."

Particularly, the 2024 study on oriental hornets shows very high alcohol tolerance.

While there are multiple anecdotes on social media of "bees that ate fermented fruits were aggressive," these are observers' impressions and not controlled experiments with managed alcohol concentration, bee species, or distance from the nest.

On the other hand, the situation changes when defending the nest.

Bees will take defensive actions if they perceive a threat to the nest or their companions.

Crushing one bee or causing disturbances near the nest can involve chemical signals that heighten alertness.

Thus, the risk is influenced not only by

"whether the bee drank alcohol"

but also by

"what actions humans took,"

"whether a nest is nearby,"

and "whether the bee is in a situation where it can't escape."

These conditions are more important.

The most dangerous is "a bee inside the glass"

In a beer garden, the real concern is not a brawl with drunk bees.

It's unknowingly bringing a drink with a bee inside to your mouth.

Special caution is needed with cans or dark bottles where the inside is hard to see.

If a bee enters the container, it is difficult to check from the outside.

Trying to drink in that state can stimulate the bee around the mouth or throat, creating a risk of being stung.

Therefore, simple measures like covering drinks, using a coaster to cover the glass, and checking the contents before drinking are highly effective outdoors.

The method practiced by German social media users of placing a beer coaster on top of the glass rather than underneath is also reasonable.

If you want to shoo them away, "don't make a fuss"

The basic rule when bees come to the table is not to fight.

NABU advises against waving hands vigorously or trying to swat them.

Blowing strongly is also not recommended.

Cover food and drinks, clean up leftovers, and if necessary, take a little distance.

Even this can significantly reduce contact opportunities.

While the idea of setting traps with beer is frequently introduced online, NABU does not recommend using beer or sweet liquids as traps.

This is because it can capture insects other than the