Tracking 32,000 Bees with QR Codes. Turns Out, Bee Foraging Is Weirder Than You Think

Honey bees are among the most cooperative and industrious creatures. Their process of collecting nectar and returning it to the hive is a remarkable example of collective decision-making involving tens of thousands of bees. Yet for all our research, there are still many mysteries about their foraging behavior—how bees evaluate nectar quality, determine travel distances, and make collective decisions.

To answer these questions, a team of researchers from Penn State University tagged over 32,000 honey bees (Apis mellifera) with tiny QR codes and monitored their activity for several months using an automated system.

A bee with an AprilTag on its back. Image credits: Penn State.

Why (and how) you tag 32,000 bees

Labeling individual bees with miniaturized QR codes is never an easy task, but it’s the best way to track thousands of bees at the same time.

“Because of the large size of honey bee colonies and the long activity period of the colony, studying foraging behavior through direct observations is generally a time-consuming endeavor. To address this need, we developed an automated imaging system for monitoring the in-and-out activity of honey bee foragers,” the study authors said. 

For their experiment, the study authors selected six apiaries (bee yards), three in Pennsylvania and three in New York. They visited these apiaries and glued AprilTags on the backs of young bees using a natural and safe adhesive called shellac glue. AprilTags are tags with black and white patterns (basically, a mini-version of regular QR codes), that help robots and cameras recognize objects and their positions. To avoid the risk of injury, the researchers tagged only young bees that hadn’t yet developed the ability to sting.

“We used AprilTags attached to each bee’s thorax to provide unique identification numbers that allowed the system to track in-and-out events throughout the foraging season of the colony,” the study authors note.

Next, they installed customized scanner systems above the apiary hives. These systems utilized cameras, Raspberry Pi computers (small single-board computers of the size of an ATM card), and some easily available ready-made components. 

Each time a bee left or entered the hive, the system automatically detected and recorded its movement by scanning the QR code.

Bee foraging is stranger than we think

Data from the BeeCam-AprilTag system revealed that while most bees traveled only up to four minutes outside their hives, some spent nearly two hours outside (though the study does not explain why). More intriguingly, bees the bees didn’t leave their hive solely for foraging.

“For instance, they often make short trips, known as “cleansing flights”, to defecate outside the hive, which typically last only a few seconds to a minute. On cloudy days, bees may also briefly exit the hive to check weather conditions before deciding whether to forage,” the study authors note. 

Additionally, new foragers take part in ‘orientation flights’ to get familiar with the area and the visual cues that help them return to the hive. These orientation flights typically last 250–300 seconds.

However, one of the most shocking findings is related to their lifespan. Generally, it is believed that a honey bee lives for about 28 days (4 weeks), but the study authors noticed them foraging for as long as six weeks (42 days).

Bees begin foraging when they are at least two weeks old, meaning these insects can actually live up to eight weeks (56 days) — challenging previous lifespan estimates.

“We found that bees are foraging for a lot longer over their lifetimes than initially thought,” Robyn Underwood, one of the study authors, told Popular Science.

An easy way to monitor the bee population

In the last 20 years, the bee population has undergone a serious decline in the US as well as other parts of the world. For instance, a study that compared the number of bee species suggests that the world has lost one-fourth of the bee species between the 1990s to 2015. 

“Several studies show that in the United States alone, beekeepers have lost about 30 percent of their colonies every year since 2006, with total annual losses reaching as high as 40 percent,” a PSU report notes.

The researchers believe that their bee monitoring system, which costs just $1,500 per apiary, could be a valuable tool not only for understanding bee behavior but also for implementing conservation strategies. 

For instance, beekeepers can use the system to monitor foraging patterns, track colony health, and assess environmental factors affecting bee activity. Real-time data from BeeCams can also help identify which particular stressors (such as pollution, pesticide exposure, etc.) are causing the decline in bee population in a particular area.

“One of the goals of developing this system open-access and with low-cost equipment was to be able to transfer this method to be replicated across dozens (or hundreds) of landscapes,”  Margarita López-Uribe, said.