You’ve probably heard about colony collapse disorder and the many problems facing our bee population. These issues have persisted for nearly a decade but this winter was particularly disastrous for US beekeepers. Between June 2024, and January 2025, 62% of commercial honeybee colonies in the United States died. That’s the largest die off on record, and it comes on the heels of a 55% die-off the previous winter. What’s going on?
We decided to ask Adam Novicki, an agriculture supervisor at the University of California’s Agriculture and Natural Resources Department. He works at the Hansen Agricultural Research and Extension Center in Camarillo. He was also, for a few years, a hobbyist beekeeper.
Evan Kleiman: So let’s talk about this past winter and what happened. Why did so many hives have so much die-off? There appears to be a number one culprit, right?
Adam Novicki: I wish it was a single smoking gun, but it’s not. The Varroa destructor is the scientific name of the varroa mite, and that mite is not from the US. It came to America, the United States, in the early 90s, and it originally was from eastern Russia, and it coexisted with another bee called Apis cerana. There’s many different bee species, and Apis mellifera is the one that we know in the West.
Long story short is the Apis cerana had evolved with that mite, and one of the things is being very vigilant about keeping them off of other bees. It’s called grooming or hygienic. Unfortunately, the Western honeybee didn’t evolve with that so that mite was able to start to infiltrate and really take advantage of bees. And there’s a number of primary consequences. It’s a vector for many viruses that affect bees, the main one is called deformed wing virus. Basically, when you have bees being compromised their immune systems, like you and I, if we get sick. It’s like when COVID was happening, people with a compromised immune system were in greater danger of perishing. Same thing with the bees. When they start to get compromised, they can’t fight off just chilly weather or other things that might be affecting them, and then the hive suffers.
How does the varroa mite operate?
That’s a very good question. There are two stages. One is a really fancy word called phoretic, which really means running around, and those are mites that a beekeeper would see when they open the hive. And those mites are often either just running around, or they are attached to an adult bee, and they’re feeding on that bee and they feed off what the bee blood is, what we call hemolymph, and they feed off that, kind of like a tick. That’s how we see them. But how they reproduce is very diabolical. The female mites will hang around the brood chamber. And a modern hive that you see a white box in a field has 10 frames inside of it. But if you imagine three dimensionally, like a football, lying on its side in that box, then taking up that space, that is the brood chamber. So those mites, those female mites, hang around that area, and they go into the cells where eggs have been laid. And as that egg develops into a larva, they begin laying eggs of their own, which can develop very quickly. So what they’ve done is they’re feeding off this larva, and they are passing that viral load into that larva. So it doesn’t kill the larva. It just diminishes its prospects. So when it’s born, it often has obvious signs of virus, deformed wing or paralysis, and those bees aren’t going to go anywhere. If you have a deformed wing, you can’t fly, so those bees will eventually die. But what’s even worse is the one that you see attached to the adult bees, those are still passing on the viral load too, but that’s called an asymptomatic transfer, and that, in and of itself, can also cause the bee to get sick.
Adam Novicki, an agriculture supervisor and former beekeeper, attributes the drastic bee die-off to the varroa mite. Photo by Therese McLaughlin.
And in a quest to fight off the mites, do bees sacrifice their own larva?
Correct. Bees have very good hearing, through their antenna, their sensory apparatus. So the development of a bee is interesting, I can tell you very quickly, it takes 21 days to form a typical worker bee. Now a drone bee, which is a male bee that only goes out and mates with other new queens, those take 24 days. Well, these mites will go into those cells, like I mentioned, and they’re developing. They love to go into drone cells, because they’re big, fatter bees that take longer. So you know, it’s like having a buffet open longer. But let’s stick with the worker bees.
They go in right before that cell is capped. And as I mentioned, it takes 21 days. So you have an egg. For three days. It’s just an egg, then it develops into a larva, and about day 10, the bees cap it, and that allows the bee to build a cocoon and metamorphosize into an adult bee, which then is hatched by itself at 21 days. Now, without getting too complicated, that in and of itself, once they capped it, the other worker bees will sense that there’s something wrong with that cell, and they will open it, and they will destroy it. They’ll pull that larva out and throw it out of the hive. Now if that keeps happening over and over again, then, you know, bees only live 42 days, so your normal population is dying off. And if you are sacrificing your newbies, then your population is going to start to plummet.
And once that starts to happen, once a hive reaches a tipping point where the mites can tell that the population is unsustainable, that it’s going to collapse, do they stay and collapse along with the bees, or do they hitch a ride out?
You know, that’s a very good question. What happens is, and this is, again, sort of cruel fate, Apis mellifera, the race of bee that is most popular for honey production is the Italian honey bee, and it’s still Apis mellifera, but it’s called ligustica, is its subspecies. Long story short, is that particular race of bees is very good at producing honey, but also very good at stealing honey. So other hives, starting with the ones next to it, will notice that that hive is weak. So what are they going to do? They’re going to go into that hive and start stealing all the honey that happens to be left over. And if the hive was strong before, it might have quite a bit of honey. So when they go in to steal the honey, the mites that are on the bees, the remember, the phoretic ones, are running around, they’re going to jump onto the other bees. And those bees will then leave and go back to their own hive, and the life cycle will begin again.
Can you briefly give us an idea of how huge this problem is?
Well, there are 1.6 million acres of almonds [in California]. Of that, 1.2 are what they call bearing. The University of California has determined that the optimum number of hives per acre is two. You need 2.4 million hives to adequately pollinate the almonds. Each hive will have minimum of 12,000 bees in each hive, but ideally more. And remember that loss happened in January, and we pollinate February to March. So if you lost 60% of your hives, there were not enough bees to pollinate the crop.
So in addition to the varroa mite, honeybees are facing two other major problems. The second issue is pesticide exposure, especially neonics. Can you tell us about that?
The biggest problem with neonics is that, for instance, they’re using corn. Bees don’t pollinate corn, but they sometimes feed off the water that corn sweats. Neonics poison bees in a sub lethal way, and what that means is the bees can’t find their way home, and if they don’t find their way home, then the population is going to suffer.
So this is fascinating to me. So first, explain what corn sweat is. I’ve seen pictures of it actually on social media. It’s startling.
Every plant has evapotranspiration, and corn is a grass, and it’s a major crop in North Dakota, where all the bees are for honey production. And when it’s humid and hot, it will sweat all the water it’s taking up from the ground, it’s putting out through its leaves. And as I mentioned, bees don’t pollinate corn. However, they need water. If they’re flying over and they stop, they will grab that sweat, those drops of water that can have traces of neonicotinoids in the bees. And the challenge is that it’s what they call a sublethal dose, so the bees don’t even find a way back for us to determine that indeed what killed them, which offers the chemical company a very convenient defense.
As you’ve pointed out, beehive die-off is caused by a host of interconnected factors, which isn’t surprising. All of Earth’s nature is just interconnected. Can you talk about how these three big issues, mites, pesticides, and also a decreasing lack of forage are all interconnected, and how they layer on top of each other?
Again, let’s go back to North Dakota. It’s the number one producing state of honey in America. So when you’re in North Dakota, they have a lot of clover. That’s why, when you see clover honey, it’s generally from North Dakota or South Dakota. Here’s the catch. It used to be they would have marginal land that could not be farmed, and those farmers then would, say it’s 10% of the acreage. Well, that’s great for the bees, because if you have soybean or corn or wheat, they’re not going to go there. But they’ve got plenty of flowers. Well, the technology has caught up where now they can farm marginal land. So because farmers have very tight margins too, they and if anyone can do that, they will. Now the term they use in North Dakota is “ditch to ditch,” meaning there’s drainage ditches. And so now you’re farming nearly 100% of your land. So it really hurt the forage, which means all the flowers. And if you don’t have enough, you’re in really bad shape for the bees, because bees need multiple kinds of sugar and multiple kinds of pollen. The pollen is the protein, the carbohydrate is the nectar. So they need a variety. It’s like if you and I just had a Cliff Bar and 7-Up, you know, I mean, we’d have our protein and we’d have our carbohydrate, but we wouldn’t be very good if that’s all we, you know, wouldn’t be good for you and I.