The Mysterious Death of Honeybees

Why are they dying? What is the cause? Haverford researchers are on the case

By Audra DeVoto

Chloe Wang tipped the glass beaker towards me, pointing out a faint impression in the tin foil covering in the shape of an X.

“See, the sharpie disappears,” she said.

The beaker had just come out of a 400º-Celsius oven (that’s 752º Fahrenheit), and any residual carbon molecules on its surfaces—sharpie included—were gone. Combusted. They had all floated away as molecules of carbon dioxide, leaving the glass and tin foil cleaner than the day it was made.

Wang was combusting carbon for a good reason. She was trying to identify chemicals that had been found on and in honeybees, and any contaminants on the glass beakers she used—no matter how small—would interfere with that process.

“I can’t use plastic pipettes because plastic is a hydrocarbon” she said, sitting down in front of a glass window that protected her from the experiments behind it—or rather the experiments from her.

“Here, the gloves are to protect the samples” Wang said.

She was surrounded by a constant buzz of machinery, air filters running, refrigerators humming, and various machines talking softly in the background. Despite the numerous benches and instruments packed into the small lab, each surface was immaculately clean. Carbon, the basic chemical building block of life, is everywhere. So keeping it off of surfaces and away from precious samples is a difficult task. Honeybee

After washing all her tools in three different chemical baths, she was ready to begin work on her sample: a small, innocuous tube consisting of two layers, a brown mush at the bottom, and a yellowish liquid on top.

The “mush” was honeybees. Ground up honeybees, to be exact. In the brightly lit, ultra clean lab deep within Haverford College’s science building, Chloe Wang was examining honeybees trying and determine chemical signatures of bee health.

She is part of a web of people consisting of farmers, beekeepers, researchers and students from two colleges, and even a large multinational corporation, all collaborating to save the bees through a novel approach—by cataloguing the chemicals a bee encounters in its lifetime, and linking those chemicals to disease and health.

And the bees, as many have realized, desperately need saving.

Back in 2006, honeybee hives started dying. Beekeepers would wake up one morning and find half, or more, of their hives gone—simply vanished. They left behind unhatched brood, plenty of honey—even their queen, unattended and alone. Even stranger, the honey left was not robbed by other bees or infested with parasites—something that normally occur within days of a hive being emptied.

In lieu of any known reason for the disappearances, and in an attempt to bring national recognition to the problem, beekeepers and scientists coined a new term for the phenomenon: Colony Collapse Disorder, or CCD.

Many environmentalists blamed neonicotinoids (or neonics), a class of insecticides that are coated on seeds before they are planted, then are taken up by the plant as it grows, allowing the pesticide to be incorporated into the plant’s very tissue. That tissue includes pollen, the logic goes, which is collected by the bees and brought back to the hive, exposing not just worker bees but the entire colony.

But neonics are just one of many chemicals bees must contend with—one study found over 118 different pesticides in pollen, beeswax, and on bees themselves—and it turns out that although neonics have not disappeared from commercial agriculture, CCD is no longer killing the bees.

That is not to say that they are safe: in 2015, the national survival rate for hives was around 44%. Rather, it means that what is killing the bees is far less understood and more complicated than neonics—and that might be the scariest thing about it.

“It’s a bad feeling,” to lose a hive, said Adam Schrieber, a local Philadelphia beekeeper. “It feels like you’ve failed in some kind of way.”

Schreiber has been keeping bees for about 7 years, but only as a hobbyist. If it’s hard to be a bee in the US right now, it might be even harder to be a beekeeper and expect to make money from it.

“Some years I’ve had really good rates of survival, seventy-five, eighty percent,” he said. “Other years like fifty percent. There are a lot of variables and a lot of reasons why a hive can die.” The biggest killers are varroa mites, small, hairy beasts that attach themselves to newly hatched bees and stay there—for life.

Varroa Mites

Varroa Mites

Compared to the bee, the bugs are enormous—approximately the size of a large rat on a human body. Other killers include deformed wing virus, which is transmitted by varroa mites, nasty bacteria that infect larvae and turn them to goop, and plain old starvation. In other words, life as a bee ain’t easy.

Nor is it easy for the men and women who keep hives.

Robert Broadrup is a small-scale beekeeper in the Philadelphia area and also the lead researcher on the bee project. Broadrup has the amount of energy one would expect of a man able to hold together a collaboration involving two colleges, a corporation (Agilent, which provides equipment for chemical analysis), and a dozen or so beekeepers—that is to say, a lot.

Broadrup’s desk is more of a table, and his office is a chemistry laboratory. As he spoke, he was interrupted by an almost continuous flow of students coming and going, asking questions and receiving answers and encouragement in reply. He clearly enjoys working in the bustle of the laboratory.

“I fell in love with bees, so what I did then in spring of 2015, I got my first hive,” he said. “My wife had OK’ed one hive, then it sort of went so quick that all of a sudden we had eight, and she’s like ‘what’.”

“I’m at 15 or something now.” he added later.

Broadrup’s research is informed by his experiences as a beekeeper.

“I want to target as specifically as possible what we do in the research to help backyard beekeepers and larger scale beekeepers” he said. “Already it’s expensive to keep bees, and then there’s a certain loss you incur when a hive dies.”

“If you’re a dairy farmer and 30-40% of your cows each year died…” his voice trailed off, the implications of that statement obvious. “Beekeepers are not rich men and women.”

The project he is leading aims to study the exposome of bees –or the total chemicals bees are exposed to over the course of their lifetime — and correlate that to the honey bee’s health and disease. Chloe Wang is a student working with Broadrup; she is responsible for determining the chemicals both inside and outside of a bee that might be useful predictors of health.

“My piece of it is grinding up the bees and trying to characterize what is in and on them” she said. The bees come from hives spread around Philadelphia in urban, suburban, and rural areas. Before she can grind them, she must first find them.

“It was really exciting to go out into the field for the first time because I’d never gone into a beehive before.” Wang said. “You have to learn the motions of beekeeping, and the choreography.”

Each beehive is made of a stack of boxes, called supers. Each super holds frames within it, where the bees build their honeycomb. Entering a hive usually requires subduing the bees with smoke, to avoid stings. Luckily, Wang didn’t have much of a problem working with bees.


“I did get stung once in the field.” she said. “I feel really calm, generally, around hives, even when they seem to be a little stirred up. […] It’s so cool really to be standing there and have the air fill with bees, and they’re making this humming sound, and you can smell the honey. It’s just a very aesthetic experience.”

In the lab, her job is to bathe the bees they collect in the field to remove any chemicals that might be lingering there. This could include anything that the bee has flown through or come in contact with, such as air pollutants.

Next, she homogenizes the bees in a blender (yes, the type of blender used for smoothies) and uses that to check for chemicals that the bee might have ingested, for example, pesticides, or anything in the honey or pollen the bee had consumed.

Wang’s data is later combined with information about the health of each beehive that was sampled, hopefully turning up correlations between certain chemicals and the health status of a bee.

Christopher Mayack is the health status guy. He has spent a lot of time figuring out how bees die, and why.

“My background is honey bee diseases,” he said. “I started working with bees in 2005, so coincidentally around the same time [as CCD]”. In graduate school, he looked at one infection in particular, that caused by the parasitic fungus Nosema ceranae.

Mayack found that nosema was stealing energy from the bees it infected, causing them to starve more quickly and—like any hungry organism—make riskier decisions in search of food. Decisions that could lower an already weakened bee’s ability to navigate home.

Mayack, along with two undergraduate students working in his lab, have spent the past year developing a way to test for the presence of different viruses, as well as the fungi nosema, in honeybees.

While the research is still being worked out—”90% of what we do is troubleshooting”, one undergraduate said—they have seen some promising results.

“The nosema [assay], we have that one figured out from start to finish.” Mayack said. In a preliminary study, they noticed that nosema infections were correlated with a compound that is found in pine resin; apparently the more nosema there was, the more pine resin there was in the hive.

“We think they collect this propolis, which has antimicrobial activities, and they use it to seal the hive” Mayack said. Propolis is a greek word that translates literally to “bee glue”; it can refer to any sort of sticky substance bees use to fill in cracks in their hive. An increase in antimicrobial propolis for hives with nosema infections might mean the bees are self-medicating, trying to kill the fungi before it kills them.

Mayack has never kept bees himself, but he has worked closely with beekeepers through his research.

“If you get beekeepers that have an appreciation for the science, they’re totally on board” he said. “It’s hard because we don’t want to raise false hopes. Research is often slow, so we’re very cautious about making false promises”.

For beekeepers, answers can’t always come soon enough. The problem is, we still know so little about all the threats facing bees, and especially how they interact with each other and with environmental factors, that it’s often difficult to even tell why a hive perished.

“You don’t always understand why.” Schreiber said. “You try to understand why it happened, sometimes it’s obvious, but a lot of times it’s not obvious. So it can be challenging to learn from those failures”.

“I think it causes a lot of beekeepers to give up,” he added.

A lack of answers, even about simple things such as the best way to manage mites, leads different beekeepers in different directions.

“If you talk to 10 people you get 15 different suggestions” Broadrup said. Schreiber’s suggestion? Chemicals might be what are hurting the bees in the first place, so he sure isn’t going to use them on his hive if he can help it. It’s a management style called “treatment free”.

“I’ve stuck with that management style because it’s more in line with how I live my own life and how I think we should all live.” he said. “For me, it didn’t make sense to put chemicals like antibiotics or what essentially amounts to pesticides […] in the beehive.”

“There are beekeepers that I know about that treat a lot,” said Broadrup. “You can buy nasty synthetic chemicals to treat hives.” The problem is, there isn’t even a lot of research on whether these chemicals work.

“Everyone’s losing hives whether you treat or don’t treat“ Schreiber said. “The differences between treating and not treating are very small… there’s a lot of variables and a lot of reasons why a hive can die.”

For now though, the beekeepers will have to wait. Broadrup and the bee project have not had a chance to finish analyzing their samples, but it is already abundantly clear that our bees are in danger. From neonicotinoids to mites, viruses to fungi, the list goes on. Oh wait; there is one more as well.

“I’ve had people steal honey out of one of my hives,” Schreiber said. Apparently the natural weaponry of a beehive is not enough to deter people, when a sweet treat is available for the taking. Who would do such a thing?

“It’s got to be someone who knows beekeeping, unless they’re really brave. Or drunk.”