Honey bees are fascinating creatures. Like all insects, they have a very different anatomy from humans. Take noses, for example. Humans have them – bees don’t.
As humans, we use our noses to smell, which helps us make decisions every day… whether that be deciding if milk has spoilt, or detecting danger from a gas leak.
Honey bees, however, do not have noses. Instead, they smell using their antennae. Fortunately, their antennae are very receptive to odors, giving them a strong sense of smell – something that is critical to their survival as a species.
How Do Bees Smell Without Noses Or Nostrils?
Honey bees smell using olfactory sensory neurons located in their antennae. These neurons have odor receptors, which detect microscopic molecules released by different substances – whether that be the smell of a predator approaching or a nearby source of nectar.
When the information is detected by the neurons, the message is sent to the brain to identify the smell and decide how to act. That decision might be to attack (in the case of a predator approaching), or it might be to land on a particular flower (in the case of detecting a good source of nectar).
Honey bees have 170 odorant receptors, which is considered high for an insect. Mosquitoes, for example, have 79. For point of reference, humans have about 400, while mice have 1,200!
Each odorant receptor is responsible for picking up a different scent. Because every creature has a different number of odorant receptors, something that smells a certain way to one animal might smell completely different to another. Honey, for example, would smell different to a bee than it does to you or me.
Honey bees use their sense of smell for a number of important tasks – locating food, communication, reproduction, and survival.
How Bees Use Smell To Detect Food
Honey bees need to collect nectar and pollen from flowers to feed the colony. Their sense of smell plays a vital role in this process.
A flower’s scent is a mixture of volatile compounds which varies depending on the type of flower, its stage of development, and local environmental conditions. Even the same species of flower may smell differently based on the time of day and how much pollen it contains.
Bees have an excellent ability to detect these differences and use them to their advantage. They visit different flowers, taking note of the scent given off by those that have lots of nectar. The next time they leave for a foraging trip, they will choose which flowers to land on based on how they smell.
This was first discovered during an experiment conducted in 1919 by ethologist Karl von Frisch. He set up a number of feeding stations that contained different essential oils. In some of these feeding stations he placed sucrose solution. The honey bees in the experiment learned to associate a particular scent with the sucrose solution, and began to choose these feeding stations over others.
Bees Use Odors To Tell Other Bees Where The Food Is
A bee’s sense of smell plays a role in alerting other bees to the location of food. After a forager bee returns to the hive, it performs a waggle dance to communicate the location of pollen and nectar to the colony. The direction and duration of the dance help to explain the location of flowers to other worker bees.
However, recent studies have found that a floral odor carried by the forager performing the dance, as well as a pheromone they release while performing it, are also important. These odors speed up the communication process and make it easier for other bees to understand where the best sources of pollen and nectar are.
Bees use a similar dance to communicate the location of nearby water sources, which are essential for a colony’s survival. Interestingly, bees tend to choose dirty water over clean water when given the choice. Though it’s not known for sure, many experts believe this is because dirty water has a stronger scent, and is therefore easier for bees to detect.
Smell Helps Bees Establish Hierarchy Inside The Hive
There is no king bee inside a colony – instead, a queen is the most important figure. She is needed to continually lay eggs to ensure the hive’s continued survival.
An established queen gives off a special pheromone that signals to worker bees who she is. As long as they can smell this pheromone, worker bees will care for the queen, feed her, groom her, and clean up after her.
The presence of this pheromone also prevents other female bees from fully developing ovaries. If a queen bee becomes sick or approaches old age, the smell she gives off will become weaker. Worker bees will detect this change in scent and raise a new queen.
If a queen bee dies suddenly, the pheromone will disappear shortly after, signaling to workers that it’s time to raise a new one as soon as possible – something they will get to work on right away.
The brood inside a beehive also give off pheromones that impact on the behavior of worker bees. These pheromones indicate to workers that developing young are present inside the colony, which inhibits them from developing their ovaries. The pheromone also helps nurse bees distinguish between drone larvae and pupae, and worker larvae and pupae.
Bees’ Ability To Smell Plays A Vital Role In Their Reproduction
The main role of male drone bees is to mate with virgin queen bees. After mating, drone bees will die. The queen stores millions of sperm inside her body and uses them to fertilize eggs for the rest of her life.
Mating takes place at a specific site called a drone congregation area. Here, large groups of drones gather in the air and wait for a virgin queen. When they become sexually mature, virgin queens fly to the congregation area and mate with multiple drones mid-flight.
The exact mix of sensory cues that enable this process to take place is still unclear. However, studies have shown that a bee’s sense of smell plays an important role.
Firstly, drones that gather in the congregation area emit a specific type of odor. This smell attracts other drones, who will fly to the site in hopes of mating with a queen. If no queen appears while they are there, they will return to the hive to eat and refuel, before going back to the congregation area. The odor of other drones guides them to the right spot.
Secondly, virgin queens are attracted to the odor emitted by drones. This helps them to find a drone congregation area when they become sexually mature. If the weather is good, they’ll visit the area multiple times over the course of a few days, sometimes mating with as many as 50 drones.
Finally, virgin queens emit a pheromone themselves, which in turn attracts drones. This pheromone plays a critical role in mating, which takes place above the ground, suspended in the air.
Like all bees, drones smell using their antennae instead of a ‘nose’ – and their antennae are specifically designed to detect a virgin queen bee. In fact, drones can smell a queen’s pheromone from as far away as 60 meters (196 feet), helping them to identify a queen mid-air as soon as she arrives.
Bees Can Smell Predators And Intruders
Another way in which honey bees use their sense of smell is to detect predators. Guard bees are able to distinguish when a potential predator (such as a bear, skunk or crab spider) is nearby based on its unique odor.
Smell also plays a vital role in alerting other bees when a hive is under attack. Bees will release an alarm pheromone from near their sting that consists of over 40 highly volatile compounds.
This pheromone tells other bees that the hive is under threat. More worker bees will spring into action and attack the predator. Many beekeepers use smoke to mask this alarm pheromone, making it easier to open and inspect a beehive without being attacked by angry bees.
Bees have another alarm pheromone which they release from their mandibular glands. This helps to repel potential intruders and robber bees from other hives. Interestingly, this same pheromone is used by forger bees to mark flowers which have been depleted of nectar, which signals to other bees there is no point landing on them.
Some people also think that honey bees can smell fear, as they are seemingly more attracted to people who are afraid of them. However, there is no scientific evidence to support this fact. It’s likely that people who are afraid simply exhibit behavior that bees think is threatening (waving their arms or ‘swatting’ at bees) and decide to attack.
See Also: Can Bees Smell Fear?
Final Thoughts…
While honey bees don’t have noses or nostrils like humans, their antennae are highly adept are detecting smells. Without the ability to smell, bees would struggle to survive. It guides their actions every day – whether it’s to locate food, communicate with other bees, or detect danger.