Real Estate

Peninsula beekeepers divided on the best way to fight a plague

Keepers disagree on whether to treat for varroa mites, which can wipe out hives

Burlingame beekeeper Bob Silverstein checks a frame from one of his hives. Photo by Philip Wartena.

Sometimes Bob Silverstein rolls his bees in sugar. It's the gentler approach to removing the parasites that often infest his hives.

When he aims for accuracy though, he can't be gentle: he grabs a metal measuring cup and a glass mason jar with a small mesh screen for a lid and brings them out to the six beehives in his backyard. Then he opens a hive, scoops out a half cup of bees and seals them in the jar. Quickly, he pours rubbing alcohol onto the 300 buzzing martyrs and swishes vigorously, drowning them all.

When the body of every bee is soaked, he drains the liquid through the mesh lid and counts the black spots that come out with it — each one is a varroa mite. If he counts too many, Silverstein — a retired orthopedic surgeon — will treat the infected hive with an oxalic acid vapor, which he likens to a doctor treating his patients.

Silverstein is among hundreds of beekeepers along the Peninsula trying to fight off the deadly mites, which are killing 40% of the country's honey bee colonies each year.

The mite epidemic is one of the first things new beekeepers learn about when they start tending bees on the Midpeninsula. The next thing they learn is that they have to pick a side: Treat the colonies or let nature take its course.

Many beekeepers insist bees can fight off the mites on their own. In order for that to work, they say, every beekeeper has to stop treating because it interferes with natural selection — the ability for bees to evolve their defense mechanisms.

"It's almost a religious divide among beekeepers," said Tori Muir, former president of the Beekeepers' Guild of San Mateo County, who like Silverstein uses strips and sprays to keep mite populations down.

Menlo Park resident David Wuertele — a treatment-free beekeeper — watched all three of his hives die last year, but he doesn't think it's because his treatment-free practices "killed" his bees.

"I believe that any attempt to treat mites prevents evolution from improving our gene stock, and interferes with treatment-free beekeepers' efforts," he wrote in an email. Wuertele — a software engineer at Tesla — sees initial losses as a part of the process of genetic evolution, which would result in stronger bees if treaters stopped keeping genetically weak bees alive with chemicals.

While locals are still struggling to come to a consensus on how to get rid of the mites, all beekeepers agree that death by varroa is traumatic.

After nesting in brood chambers alongside growing bee pupae, varroa mites hatch and pierce through the abdomen of adult bees to feast on an organ called "fatty tissue," which helps control the bee's immune system. This weakens the bees and leaves them highly susceptible to crippling diseases like Deformed Wing Virus.

Guild member Nickie Irvine, who has been beekeeping for 15 years, confronts the scourge without chemicals, but she doesn't exactly leave the bees to do it on their own, either.

After teaching environmental anthropology at Stanford University for 25 years, Irvine is well-versed in research and the scientific method. She now approaches each of her backyard hives as a genetic experiment to test different ways of reducing varroa numbers without using chemical treatments.

When word spread that some Russian bees had adapted to better withstand varroa, she bought queens from those colonies.

If she sees good resistance in a hive — from Russian or other strong genes — she'll split the hive so the strong bees can raise a new queen, which creates two healthy hives from one.

Other times she'll graft larvae from one hive into another to spread the strength of the gene pool.

There's no shortage of creative (if not complex) alternatives to treatment, so in the quest for a solution to the varroa epidemic, Irvine would like to see more tolerance of beekeepers who explore unconventional methods.

"We need to let more people experiment to see what works and what doesn't," she said.

On the Peninsula, no sentinel hives — colonies that are heavily monitored to detect the presence of varroa — can warn beekeepers, because the mites have been in California since at least 1989. The question is not if a hive will get varroa, it's when. Many backyard beekeepers weigh factors like honey production, the bees' suffering and chemical toxicity when considering treatment options, but those aren't necessarily in line with the nature of a hive.

"Bees are brutally community minded," Muir said. "It's all about what helps us — (the colony) — survive. There's no cult of personality or anything — with them it's just about metrics."

She explained how in winter, when resources are scarce, the colony will push drone bees out of the hive to starve. Or, if a queen is underperforming, how the colony will raise a new queen and huddle around the old one, beating their wings furiously until she explodes from the heat. It's a merciless version of altruism that few beekeepers dare simulate.

Irvine said she doesn't think she could stomach killing an entire colony suffering from high numbers of varroa mites — which some researchers advocate — but she'll move larvae and buy queens.

Silverstein and Muir prefer the oxalic acid treatment, but every approach has its tradeoffs.

"The people who monitor for mites year round and treat whenever the mite population starts spiking up, they (rarely) lose hives," Muir said. "But very few people want to keep bees that way, and at some point you have to question — you're keeping them alive, but at what cost, because you're constantly treating for mites."

Kali Shiloh writes for the Weekly's sister publication The Six-Fifty. You can reach her at


Two local beekeepers' guilds welcome both new and experienced beekeepers.

Beekeepers' Guild of San Mateo

Meets the first Thursday of the month in San Carlos. or

Santa Clara Valley Beekeeping Guild

Meets the first Monday of the month in San Jose. or 408-634-BEES

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2 people like this
Posted by CrescentParkAnon.
a resident of Crescent Park
on Jul 9, 2019 at 1:13 am

This is the first year that I have not seen a single Honey Bee out pollinating flowers.
I am sure there must be some, I hope.
All I see in my garden are yellowjackets, little buzzing insects, and bumblebees or some kind or another.
I like Honey Bees .... I hope they can bring them back.
Does anyone know if the disappearance of the Honey Bee is due to all the insecticide we use.

Like this comment
Posted by Donny Moscow
a resident of Community Center
on Jul 9, 2019 at 9:41 am

Not only letting new pesticides kill bees, we are now refusing to count the dead.

"On the heels of the EPA’s June approval of a bee-killing pesticide, the White House said it would stop collecting data on declining honey bee populations—potentially making it impossible to analyze the effects of the chemical and the administration’s other anti-science policies on the pollinators."

Numbers, facts, etc.. are fake need. So stop counting.

Donny Moscow

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