Varroa Mite History in the United States: From First Detection to Today

By 1995, varroa had spread to all 48 contiguous US states, leading to the collapse of 60% of managed US colonies within a decade. Those numbers represent one of the most severe agricultural pest introductions in American history -- not in the abstract, but in actual operations, livelihoods, and the cultural institution of American beekeeping.

Understanding this history helps put current varroa management practices in context. The treatments, thresholds, and monitoring protocols we use today weren't invented in a vacuum. They were developed by researchers, beekeepers, and regulators responding to a crisis that reshaped everything about how Americans keep bees.

TL;DR

• This guide covers key aspects of varroa mite history in the united states: from first detecti
• Mite monitoring should happen at minimum every 3-4 weeks during active season
• The 2% threshold in spring/summer and 1% in fall are standard action points based on HBHC guidelines
• Always run a pre-treatment and post-treatment mite count to calculate efficacy
• Treatment records including product name, EPA number, dates, and counts are required for state inspection compliance
• VarroaVault stores all monitoring and treatment data with automatic threshold comparison and state export formatting

---

1987: First Detection

Varroa destructor was first detected in the United States in October 1987, in a bee yard in Adams County, Wisconsin. USDA researchers confirmed the identification -- this was the same mite that had devastated bee populations in Europe after its introduction from Asia.

The detection triggered immediate action from USDA APHIS. A tracing operation identified the origin of the infested bees and the extent of potential exposure. State departments of agriculture were alerted. The scale of the problem became clear quickly: varroa had almost certainly arrived before that Wisconsin detection, and by the time it was found, it had spread beyond the immediately traceable source.

1988-1992: Rapid Spread

The biology of varroa spread is unforgiving. A single infested colony in a region with active bee commerce and natural bee drift can serve as a source for dozens of nearby operations within a season. Forager bees that rob infested colonies carry mites back to their home hive. Drifting bees move between adjacent apiaries. Queens purchased or traded from infested operations spread the mite along established commerce routes.

Within 5 years of first detection, varroa was documented in 30+ states. The spread was faster in regions with dense beekeeping activity -- the Northeast corridor, the Midwest corn belt, and the Southeast. Western states saw detection slightly later due to geographic barriers and lower bee commerce density.

The feral bee collapse: Perhaps the most significant early consequence was the collapse of feral honey bee populations. Before varroa, feral colonies were common throughout the US -- cavity-nesting swarms in hollow trees were so prevalent in some regions that they were considered a nuisance. These feral populations provided a constant supply of swarms for hobby beekeepers and maintained wild pollinator populations in areas without managed hives.

Varroa eliminated most of this feral population within a decade. Untreated colonies without human management don't survive varroa without some degree of inherent resistance -- and the domestic honey bee populations that had formed the feral reservoir lacked that resistance. By the mid-1990s, the sound of feral bees had largely disappeared from much of rural America.

1992-1995: Reaching All 48 States

By 1995, varroa had been detected in all 48 contiguous states. This achievement (from the mite's perspective) represented 8 years from first detection to complete national coverage -- one of the fastest documented spreads of a beekeeping parasite in US history.

The combination of bee commerce (queens and packages sold across state lines), migratory beekeeping (commercial operations that move hundreds of hives across the country for pollination contracts), and the biological reality of bee drift and robbing created the conditions for this rapid spread.

1995-2005: The Response Era

The decade after varroa reached all 48 states was defined by the development of a management response:

Tau-fluvalinate (Apistan): The first widely used varroa acaricide in the US. Apistan strips, applied in the brood nest, produced strong efficacy against varroa mites and were quickly adopted by the industry. For several years in the mid-1990s, Apistan dominated varroa management.

Coumaphos (CheckMite+): A second synthetic acaricide, registered for varroa use in 1999. Provided an alternative to Apistan as resistance began to emerge.

Resistance emergence: By the late 1990s, tau-fluvalinate resistance was documented in US varroa populations. Beekeepers who had used Apistan exclusively as their primary treatment for several years found efficacy declining. The resistance problem validated what researchers had been warning about: relying on a single product class inevitably selects for resistance.

Organic acid treatments: Oxalic acid and formic acid treatments were already in use in Europe and came under research focus in the US during this period. EPA registration for US-labeled products came later, but beekeepers were increasingly aware of organic alternative approaches.

2005-2015: Losses, Colony Collapse Disorder, and Policy Response

Colony Collapse Disorder (CCD) emerged as a documented phenomenon in 2006-2007, characterized by sudden disappearance of adult bees from hives without the normal accumulation of dead bees. The cause of CCD was debated extensively; current scientific consensus holds that it resulted from a combination of varroa-transmitted viruses (particularly DWV), pesticide exposure, and other stressors acting together rather than any single cause.

The national attention on CCD accelerated policy and funding:

• USDA APHIS established the National Honey Bee Disease Survey
• The Honey Bee Health Coalition was formed as a multi-stakeholder coordination body
• EPA accelerated registration reviews for organic acid treatments
• Federal and state funding for varroa research increased

Api-Bioxal registration (2015): The EPA's registration of oxalic acid (Api-Bioxal) for use in US hives in 2015 was a landmark. For the first time, beekeepers had a federally registered organic acid treatment that could be used legally. OA vaporization and dribble applications moved from a gray area into full compliance.

2015-2026: The Current Era

The current era is characterized by:

Multiple registered treatment options: US beekeepers now have access to a full range of registered treatments including oxalic acid (dribble and vaporization), formic acid (MAQS, Formic Pro), amitraz (Apivar), and several organic options. This breadth of options supports the product rotation that prevents resistance development.

Documented resistance management challenges: Tau-fluvalinate resistance is well-established in US populations. Amitraz resistance is emerging in some geographic clusters. Resistance surveillance is now part of the national monitoring framework.

Digital management tools: The 2020s have seen the development of dedicated varroa management software -- tools built specifically for count tracking, threshold alerts, PHI calculation, and treatment record keeping. This infrastructure was not available to the beekeepers who fought the initial varroa crisis.

Persistent annual losses: Despite improved tools and protocols, annual colony loss rates have remained elevated. The 2024-2025 Honey Bee Health Survey reported approximately 36% annual colony losses nationally. The gap between the achievable loss rate (10-15% for beekeepers following structured protocols) and the national average reflects a persistent monitoring and management gap across the industry.

The what is varroa destructor guide covers varroa biology for beekeepers new to the subject. The complete varroa management guide covers current management protocols in full.

Frequently Asked Questions

When was varroa first found in the US?

Varroa destructor was first detected in the United States in October 1987, in Adams County, Wisconsin. USDA researchers confirmed the identification after a beekeeper reported unusual colony losses. The detection was already past the initial introduction point -- by the time varroa was identified, it had almost certainly spread beyond the immediately traceable source operation. The detection triggered a national response that ultimately couldn't contain the spread.

How quickly did varroa spread across America?

Varroa spread from first US detection in Wisconsin (1987) to all 48 contiguous states by approximately 1995 -- roughly 8 years for complete national coverage. The spread was accelerated by interstate bee commerce (queen sales, package bees), migratory beekeeping operations, and the natural transmission mechanisms of bee drift and robbing between neighboring hives. The speed of spread was faster in regions with dense beekeeping activity and established interstate bee commerce networks.

What changed in US beekeeping after varroa arrived?

Varroa fundamentally restructured American beekeeping. The feral honey bee population that had existed throughout the country largely collapsed within a decade of varroa introduction. Commercial beekeepers faced unprecedented colony loss rates that drove many operations out of business. Treatment protocols, resistance management practices, and monitoring standards had to be developed from scratch. Federal research and registration priorities shifted to address the crisis. And the hobby beekeeper experience changed permanently -- keeping bees in the US now requires active varroa management as a baseline practice, not an advanced option.

How do I know if my varroa treatment is working?

Run a mite count 2-4 weeks after the treatment ends and compare it to your pre-treatment count. The efficacy formula is: ((pre-count - post-count) / pre-count) x 100. A result above 90% indicates effective treatment. Results below 80% should trigger investigation for possible resistance, application error, or reinfestation. Log both counts in VarroaVault to track efficacy trends across treatment cycles.

How often should I check mite levels in my hives?

At minimum, once per month (every 3-4 weeks) during the active season. Increase to every 2 weeks when counts are near threshold or after a treatment to verify it worked. In fall, monitoring frequency matters most because the window to treat before winter bees are raised is narrow. VarroaVault's monitoring reminders can be set to your preferred interval for each apiary.

What records should I keep for varroa management?

Each record should include: date of count or treatment, hive identifier, monitoring method used, number of bees sampled, mites counted, infestation percentage, treatment product name and EPA registration number, dose applied, treatment start and end dates, and PHI end date. State apiarists typically expect this level of detail during inspections. VarroaVault captures all of these fields in a single log entry.

Sources

• American Beekeeping Federation (ABF)
• USDA ARS Bee Research Laboratory
• Honey Bee Health Coalition
• Penn State Extension Apiculture Program
• Project Apis m.

Get Started with VarroaVault

The information in this guide is most useful when you have your own mite count data to apply it to. VarroaVault stores every count, flags threshold crossings automatically, and builds the treatment history you need for state inspections and effective management decisions. Start your free trial at varroavault.com.