Starting around 1904–1906, beekeepers on England’s Isle of Wight began finding their colonies crawling with dying bees and collapsing outright at the height of summer — the opening of an epidemic so severe that by the early 1920s it had wiped out an estimated 90 percent of honey bee colonies across Britain and Ireland. It became known simply as “Isle of Wight disease,” and more than a century later, scientists still don’t fully agree on exactly what caused it.
Key Takeaways
- Isle of Wight disease first appeared in reports from beekeepers on the Isle of Wight in the mid-1900s decade, then spread to the British and Irish mainland, recurring in waves between roughly 1906 and 1919.
- By the early 1920s, an estimated 90 percent of honey bee colonies in Britain and Ireland had been lost to the epidemic.
- In 1921, researcher Rennie identified the parasitic tracheal mite Acarapis woodi in affected bees and concluded it was the cause — a diagnosis that stood as the accepted explanation for decades.
- In 1991, researchers Bailey and Ball challenged that consensus, concluding the epidemic was primarily caused by chronic bee paralysis virus (CBPV) rather than the mite alone, even though the mite was reliably present in affected colonies.
- The crisis in Britain is part of the reason the United States passed the Honeybee Act of 1922, restricting live bee imports specifically to keep the same disease out of American colonies.
Table of Contents
- A Mysterious Die-Off Begins
- Ninety Percent of a Nation’s Bees
- 1921: A Culprit Is Named
- 1991: The Diagnosis Gets Overturned
- Brother Adam’s Response: Breeding for Resistance
- Why This Mattered to American Beekeeping
- Frequently Asked Questions
A Mysterious Die-Off Begins
Beekeepers on the Isle of Wight, a small island off England’s south coast, began reporting a strange and alarming pattern in the mid-1900s decade (accounts place the earliest reports between 1904 and 1906): bees crawling helplessly on the ground outside their hives, unable to fly, with entire colonies collapsing during what should have been the height of the productive season. There was no known treatment and, at first, no identified cause — just a pattern of loss severe enough that it quickly became the defining beekeeping crisis of the era. The affliction recurred in waves at least three times between 1906 and 1919, rather than passing as a single isolated outbreak.
Ninety Percent of a Nation’s Bees
The disease did not stay confined to the island it was named for. It spread to mainland England and then across Britain and Ireland, and the scale of loss it caused is genuinely difficult to overstate: by the early 1920s, an estimated 90 percent of honey bee colonies across Britain and Ireland had been wiped out. For a country with a long-established beekeeping tradition, that represents one of the most severe single epidemics ever documented in the history of Western apiculture — comparable in scale, if not in cause, to what Varroa mites would later do to feral bee populations in North America after their own arrival in 1987, a story covered separately on this site.
1921: A Culprit Is Named
The disease went unexplained for roughly fifteen years before researcher Rennie identified a previously undescribed parasitic mite living in the tracheae — the breathing tubes — of affected adult bees, later named Acarapis woodi. The 1921 identification gave the epidemic a named cause for the first time, and “acarine disease” became the accepted scientific term, even as “Isle of Wight disease” remained the common name most beekeepers continued to use. For decades afterward, the tracheal mite was treated as settled science: the single identified cause of one of the worst honey bee epidemics on record.
1991: The Diagnosis Gets Overturned
Seventy years after Rennie’s identification, researchers Bailey and Ball revisited the evidence and reached a genuinely different conclusion: in a 1991 analysis, they argued that Isle of Wight disease was not caused primarily by the acarine mite at all, but by chronic bee paralysis virus (CBPV) — a distinct pathogen whose symptoms, including bees crawling helplessly outside the hive, closely match the historical accounts of the epidemic. Crucially, their argument doesn’t claim the mite was irrelevant or absent; Acarapis woodi was reliably found in affected colonies, which is exactly why it had been blamed in the first place. Their conclusion was that the mite’s near-constant presence in sick colonies didn’t prove it was the primary cause, if a virus capable of producing the same symptoms was circulating at the same time. More than a century after the epidemic began, this question doesn’t have a single, universally settled answer.
Brother Adam’s Response: Breeding for Resistance
One of the epidemic’s most consequential legacies came out of Buckfast Abbey in England, where the monk Brother Adam responded to the devastation by developing a new honey bee strain bred specifically for resistance to the disease — work that eventually produced the Buckfast bee, a hybrid still used by beekeepers worldwide today and covered in full in this site’s guide to Buckfast bees and Brother Adam’s breeding program. It’s a direct example of a specific historical crisis producing a specific, lasting technical solution: an epidemic that couldn’t be cured led instead to breeding a bee that could better survive it.
Why This Mattered to American Beekeeping
The scale of the British and Irish losses didn’t go unnoticed across the Atlantic. American beekeepers and entomologists, watching a disease with no reliable treatment eliminate the vast majority of a country’s honey bee population within roughly fifteen years, pushed for preventive action rather than waiting to find out whether the same affliction would arrive in a shipment of imported queens. That pressure led directly to the Honeybee Act of 1922, the federal law this site covers in detail separately, which restricted live honey bee imports into the United States specifically to keep the disease devastating Britain from reaching American colonies.
Frequently Asked Questions
What actually caused Isle of Wight disease?
It’s genuinely disputed. A tracheal mite, Acarapis woodi, was identified as the cause in 1921 and accepted for decades, but a 1991 re-analysis by researchers Bailey and Ball concluded the epidemic was primarily driven by chronic bee paralysis virus, with the mite present but not necessarily the primary cause.
How many bees died from Isle of Wight disease?
By the early 1920s, an estimated 90 percent of honey bee colonies across Britain and Ireland had been lost to the epidemic, which recurred in waves between roughly 1906 and 1919.
Why is it called “Isle of Wight disease” if it spread across Britain?
The earliest reported cases came from beekeepers on the Isle of Wight, off England’s south coast, in the mid-1900s decade, and the name stuck even after the disease spread to the mainland and across Ireland.
Did the Isle of Wight epidemic affect American beekeeping?
Indirectly, yes. Concern over the disease reaching the United States was a major factor behind the Honeybee Act of 1922, which restricted live honey bee imports specifically to prevent the same epidemic from crossing the Atlantic.
What is the connection between this epidemic and the Buckfast bee?
The monk Brother Adam at Buckfast Abbey developed the Buckfast bee specifically in response to the epidemic, breeding for resistance to the disease that had devastated British colonies — a program that produced a hybrid strain still used by beekeepers today.
For additional context, see the journal Nature.
