In my last piece I made the case that the rumors of honeybee extinction have been greatly exaggerated, but honeybees are still suffering larger than usual losses, and some wild bees are probably going extinct.

So what is it that’s hurting bees? And what are our options for helping them?

In working to figure this out, I bumped into Randy Oliver on the UC Davis campus. Oliver is a beekeeper based in the California foothills of the Sierra Nevada. He’s tall and lean with an unapologetic ’70s mustache. He’s been writing extensively to try to understand what’s happening to bees, drawing on the scientific literature and his own experience, and he made a lot of sense.

I was drawn to Oliver because I have a lot in common with him: He lives just outside my hometown, amid the ponderosa pines. He cares a lot about science, and the environment, and keeps an organic garden for himself. Plus, he likes to investigate the facts behind popular controversies at exhaustive length. Oliver wrote a voluminous series on colony collapse for American Bee Journal, which is similar in many ways to the several series I’ve done at Grist on GMOs, local food, and feeding the world.

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I had been thinking I might do a deep dive to figure out what we know about honeybees, but it turned out that Oliver had already written it.

Oliver found that, every so often, something goes wrong with the bees. In 1984, mites that live in bee tracheas moved in and killed 70 percent of the bees in California. But the bees eventually evolved resistance to the mites, and a few years later, Oliver found that he didn’t even have to treat for them. (This is yet another example of a previous bee crisis that the press ignored.)

Then, in the early 1990s, a new parasite attacked the bees: Varroa destructor. The Varroa mite had come to the U.S. as a parasite of Asian bees, then evolved to parasitize European honeybees. Varroa mites were triply traumatic because they (1) introduced lots of germs and viruses by piercing bees with syringe-like mouth parts, (2) seemed to have the ability — common to parasites — to weaken bees’ immune systems, and (3) extracted a lot of energy from bees by sucking their hemolymph (that’s bug blood). Oliver wrote:

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Varroa brought me to my knees; recovery was much harder, but I was still eventually able to greatly expand my operation.

However, things were no longer the same. Queens would fail, and colonies would go queenless. Winter losses were higher. Beekeeping was just tougher. Dave Mendes notes that “bees are simply more ‘fragile’ than they used to be.”

Then in 2004 and 2005 my bees weren’t right. At first they just didn’t build up normally, and often exhibited the odd diseases in the photos above. Then they suffered serious fall and winter collapses (a fellow beekeeper in the same area lost thousands of colonies, but oddly, not so another buddy with yards alongside ours!). We erroneously blamed it on the mosquito spraying due to the West Nile Virus scare — further investigation did not support that link. And when I asked the growers, they hadn’t changed seed type nor pesticide use (most didn’t use any) for years. I couldn’t keep my numbers up, and was puzzled and distraught.

Then Dave Hackenberg made the news when he suffered unusual colony collapses in 2006. The point that he made was not that he suffered losses, but rather that the degree of the losses and way in which colonies collapsed, was unlike anything he had ever seen before. Something had changed!

The fact that something was different was the first clue. The proximate cause of colony collapse disorder had to be something that didn’t exist before the mid-2000s:

What bugs commercial beekeepers is when folk blame long-time practices for this new problem: we’ve been trucking bees, using plastic foundation, feeding syrup, and had varroa mites for some time, and our bees generally thrived (as long as we kept mite levels down). So I’d discount any purported cause that hadn’t changed shortly prior to the appearance of CCD.

That knocked out a lot of the usual suspects, leaving Oliver to guess he was dealing with a new disease. The varroa mites had made the bees more fragile and provided a new avenue for infection, and then something truly nasty had come along, he hypothesized. When bees get really sick, they leave the hive en mass: It’s called “altruistic suicide,” and it protects the rest of the colony from infection.

Oliver wanted to test his hypothesis. He took 72 hives and set them away from the rest. Then he ground up some really sick bees and gave this pathogen-slurry to a few bees in each hive. It worked: Within a few weeks he was seeing massive die-offs, and the classic disappearance of colony collapse.

Scientists have come to a vague conclusion that the cause of colony collapse disorder is multifactorial: the bees are weakened (by mites, and chemicals); they get lots of diseases; and they die. But in a way, that’s beside the point. Actual CCD — colony collapse disorder — officially ended sometime around 2009. Since then, beekeepers have been reporting higher than average bee deaths, but not the widespread disappearances of hives that gave rise to the alarm.

Today, the question is: Why are honeybees suffering — and are the same things hurting wild insects? Herewith, a brief tour of the likely suspects.


There’s plenty of evidence that a big dose of neonicotinoids will kill bees. They are insecticides, and bees are insects, after all. But the evidence suggests that the small doses honeybees get in most real world situations aren’t killing them.

Neonics come as seed coating. When seeds germinate and plants grow, they draw in the pesticide. There’s not that much to begin with, and very little makes it all the way up to the pollen.

As a beekeeper, Oliver is less worried about neonics than spray pesticides, which can cause major bee kills. A breeder of leafcutter bees, which survive solely on neonic-treated canola flowers, told Oliver that he’d never seen a problem with his bees. The two big field trials of bees in neonic-treated crops also suggest that honeybees aren’t affected by the amount of chemicals they are getting. The neonic makers helped pay for both those trials, but they are supported by another study funded entirely by government and nonprofits at Lund University in Sweden. That study suggested that neonics hurt wild bees, but not honeybees.

“This doesn’t mean that there aren’t any negative effects on honeybees, but so far I don’t see any evidence from field studies supporting that,” the lead author Maj Rundlöf told Nature.

It seems unlikely that neonics are the primary culprit when it comes to honeybee losses — but that doesn’t mean they are blameless. There are several studies suggesting that neonics hit wild bees harder than honeybees, and this is particularly problematic because they can stick around in the soil for up to two years. And their breakdown products may hurt insects and worms in the dirt. Because neonics come with the seeds, farmers are putting them in the ground even when they aren’t needed. “They are vastly overused,” Oliver said.

In 2013, the European Union instituted a two-year ban of neonics, and France has banned their use in bee-attracting crops since 1999. But so far, honeybee health in France hasn’t noticeably improved.

In sum: Neonic seed-coatings probably aren’t causing domestic honeybee die-offs, but they are likely to be hurting wild pollinators and soil critters.

Neonics + air-pressurized planters

“This is a bleeding wound with the bee industry,” Oliver said. Modern planters use pressurized air to move seed through the machinery and into the soil. As seeds bump around in the tubes, their coatings can come off. Corn seed, especially, because it’s not round, abrades the coating. When the air comes blowing out of the planters, it carries a fine dust of concentrated neonics, which can float for long distances. Beekeepers and farmers alike agree that dust from planters has caused major bee kills. Deflecting planter vents down toward the ground — or filtering the air — can reduce the problem.

Other pesticides

The connections between bee declines and pesticides are … complicated, as Brad Plumer at Vox has put it.

Pesticide use has improved immensely, Oliver said. Throughout his career as a beekeeper, farmers have been reducing their insecticide use. “In the ’60s and ’70s, we used to get bee kills all the time,” Oliver said. “Now I’m not seeing pesticide being the main issue for most beekeepers.”

Many pesticides are trapped in bee wax, so you can compare current hive exposures to wax from years ago. Oliver dug up an analysis of bee wax from the pre-neonic era and found much higher concentrations of chemicals (including DDT and PCBs) than exist in current hives. If pesticides were the main issue, bee health should be getting better, not worse.

However, even if pesticides aren’t the main issue for beekeepers, they are still a real problem. Bees are getting exposed to a lot of chemicals. Some of those chemicals — like fungicides, and herbicides, and even supposedly inert ingredients — aren’t supposed to kill bees, but they can have sublethal effects that compromise bee health. Oliver writes:

Oh man, is this a touchy subject, with some very strong and adamant opinions out there!  Beekeepers have long noticed that colonies set in certain agricultural areas go downhill, or may not make it through the following winter.  Sometimes a certain pesticide is clearly to blame; other times it may simply be due to the lack, or poor nutritional quality, of the forage in the agricultural area, especially in this age of “clean farming” and wall to wall corn or soy.

Almond pollination is especially rough on bees, because the almond bloom comes so early in the year, before hives fully rebound up from their winter hibernation. And that’s just the beginning. Here’s Oliver:

Prior to, and just after bloom, the poor bees suffer from famine (since there is virtually nothing to eat on the orchard floor), from unexpected cold snaps, are exposed to strains of parasites from all corners of the country, and must detoxify both the natural amygdalin in the almond pollen, as well as the fungicides and insect growth regulators from the incessant spraying of the bloom!

If the almond bloom weren’t so nutritious and stimulatory to broodrearing, many colonies would not be able to recover from the pre-bloom stress.  And some in fact don’t.  And if they are not moved out of the orchards soon enough after the petals fall, strong colonies can quickly get sick due to lack of pollen income.

As you can see, it’s hard to disentangle chemical exposure from the demands of industrial agriculture. There’s no doubt that working hives hard, and trucking them around the country from bloom to bloom, is tough on bees. But it’s not like we’ve just started doing this. Bee scientist Dennis vanEngelsdorp points out that humans have been moving hundreds of hives at a time for thousands of years, since the Egyptians were shipping their bees up and down the Nile on barges.

The biggest issue with agriculture is simply the act of converting habitats where bees can thrive into habitats where they starve. Which brings us to …

Habitat loss

Oliver likes to point out that humans are bees’ No. 1 competitors. We are forever paving over their foraging grounds and mowing down fields of clover and daisies so that they stay flat and green. And of course the same is true of farming, which destroys the burrows of wild ground-nesting bees, as well as eliminating blooms. Oliver writes:

It strikes me as odd that when people think of the impact of farming upon bees that they focus upon pesticides.  In truth, the most destructive annihilator of natural ecosystems is the act of tillage — the mechanical preparation of land for the growing of crops.

Oliver describes intensively farmed areas as green deserts: Put a hive in the wrong spot and the bees would starve, though they are surrounded on every side by lush vegetation. “Formerly bee-friendly farmland has been turned into agri-deserts devoid of any bee forage,” he writes.

Of course, bees get pollen and nectar from farms, too. But most crops have a short window of flowering. Soy flowers for just a few days, corn for about a week. We harvest many other crops before they bloom (broccoli and lettuce, for instance). Farms with pastures do supply bees with nutrition and habitat — alfalfa and clover bloom for a long time. But many farms no longer incorporate pasture as part of their system. Animals are raised in one pace, their feed (often corn and soy) in another. In addition, farmers are plowing under a lot of flowers on former Conservation Reserve Program land and planting corn.

Conservation Reserve Program land has declined over the last few years

Conservation Reserve Program land has declined over the last few years.Agricultural Economic Insights

The way we’ve changed the land in general has meant less food for bees. Some of the land use changes hurting bees are counterintuitive. For instance, the eastern forests, in their regrowth, have shaded out bee meadows and closed dozens of former corn fields that were once ringed with flowers. Overall, human land management has given bees steadily fewer options. As Hannah Nordhaus puts it in her meticulously researched book, The Beekeeper’s Lament:

Bees may be suffering from the same kind of malnutrition afflicting humans who eat processed junk food. The problem is compounded by the lack of natural forage. Sprawl, monocrops, flawless lawns, weedless gardens, and a general decline in pastureland have made it hard for bees to find a suitable diversity of nectar and pollen sources.


There’s no evidence that GMOs are hurting pollinators directly, and solid evidence that they are hurting pollinators indirectly. Oliver looks at the potential for direct effects in greater depth — you can cross-examine his conclusions here — but the insecticide in insect-resistant GMOs only targets a select group of insects, mostly caterpillars, and not bees. If anything, insect-resistant GMOs have been good for bees, because they have allowed farmers to reduce the amount of insecticide they use. Herbicide-tolerant GMOs, on the other hand, have allowed farmers to control weeds much more effectively — but for the bees, those weeds used to be dinner.

But Oliver doesn’t think herbicide-tolerant crops are bad. The embattled weeds growing between cornrows never provided great nutrition for bees. And he points out that there’s a fairly zero-sum tradeoff between the efficiency with which a farmer can grow crops and the amount of land we cultivate for agriculture. Jesse Ausubel has suggested that, thanks to improvements in farm efficiency, we are past the point of peak farmland. Herbicide-tolerant GMOs are part of that improvement in farm efficiency.

The problem is that the land saved via farm efficiency doesn’t automatically turn into pollinator habitat. Often, when farmland goes out of production, it’s converted to housing and strip malls.


The main problem here may be that we’ve bred a variety of particularly fragile bees. Of course, no one set out with the intent of breeding for fragility, but there’s always tradeoffs in breeding.

The modern honeybee is wonderfully industrious — so hard working that it doesn’t stop to groom itself, which is a problem when you have parasites. Bee breeders have selected for single-minded foraging for so long that modern bees are like type-A businesspeople — they work without stopping to care for themselves. Bee breeders are working on a line of “hygienic bees” which spend time removing parasites, but that would also mean they would be a little less efficient as workers.

Similarly, we’ve bred for bees that don’t spend a lot of time collecting sap from plants — and this may have been a big mistake. Many plants emit sap when wounded to protect themselves from infection; bees gather these resins and use them to protect the colony from invaders. The sap the bees bring back to the hive is what beekeepers call propolis. “Perhaps we have been shooting ourselves in the foot by breeding for bees that don’t use much propolis,” Oliver writes.

“There’s just not a lot of genetic diversity,” Hannah Nordhaus told me. “They are all coming from the same 40 queen breeders in northern California.” But scientists and hobbyists are trying to breed more diversity back into the honeybee stock. (Charles C. Mann wrote a great piece on this recently.)

The big picture

A lot of things are ganging up on bees. As Nordhaus puts it in her book:

a combination of factors is probably responsible — some sort of interaction between pathogens and variables such as nutrition, weather, varroa mites, pesticides, and the modern insults of long-distance beekeeping. “I still go back to the death-by-a-thousand-paper-cuts theory,” says [beekeeper John] Miller.

But can we rank those factors? “Yes, it is multi-factorial, but if you took away the varroa mite, the other factors wouldn’t be nearly as bad,” Nordhaus said. The next big problem is probably lack of nutrition, meaning lack of flower-filled land, she said. The White House recently released a plan to aid pollinators, mostly by restoring 7 million acres of bee (and butterfly) habitat. Some researchers and activists have criticized this plan because it doesn’t say anything about pesticides. It’s harder, politically, to get farmers to give up pesticides — and, on a global scale, use of less pesticides could mean plowing up more land. But not necessarily.

Farmers, talking to me privately, have said that they know they are using neonic seed treatments when they’re not needed — it has become second nature, and the industry standard. Perhaps the White House should consider offering farmers an insurance policy against pest damage in exchange for trying non-neonic seeds. After all, an EPA study found that, on soybeans, the neonics provided no economic benefit to farmers. If that’s true, no farmer would ever have to collect, and the insurance program would be a freebie for taxpayers. Why not test that out? There may be a way for farmers, bees, and the people who love them all to win.

Finally, after all this left-brained evidence and analysis, let me leave you with Dennis vanEngelsdorp, reminding us about why we should care in the first place: bees are wonderful!

VanEngelsdorp ends with a suggestion. There’s something anyone who has control over a little piece of land can do: Transform lawn, or concrete, or barren median strip into a bee-meadow. Insects just need a place to live and land that fosters food they can eat. There’s lots of land available, if we can accept a bit of wilderness in our midst.

So far I’ve been looking mostly at commercial honeybees. Next I’ll write about wild pollinators, which are also struggling, and don’t have beekeepers to help boost their populations.