Varroa Mite Statistics

Biology

Where Varroa came from and how it reproduces

Varroa destructor is an Asian mite that switched hosts to the Western honey bee. It breeds inside capped brood cells and feeds mainly on the bee's fat body tissue.

1. Varroa is native to Asia, where its original host is the eastern or Asian honey bee, Apis cerana, which rarely suffers serious harm from the mite. (Source: UF/IFAS Extension, EENY-473, revised 2022)
2. Evidence suggests the mite's host shift to the Western honey bee may have taken 50 to 100 years after Western bees were brought into Asia. (Source: UF/IFAS Extension, EENY-473, revised 2022)
3. Varroa mites spread to the United States from Southeast Asia in 1987. (Source: USDA ARS news release, 2022)
4. Adult female Varroa mites measure 1.00 to 1.77 mm long and 1.50 to 1.99 mm wide. (Source: UF/IFAS Extension, EENY-473, revised 2022)
5. After entering a brood cell, a foundress mite lays fertilized eggs about every 25 to 30 hours. (Source: UF/IFAS Extension, EENY-473, revised 2022)
6. On average, a foundress mite produces about one offspring per worker cell she enters and about two per drone cell. (Source: UF/IFAS Extension, EENY-473, revised 2022)
7. Varroa mites are attracted disproportionately to drone brood. (Source: UF/IFAS Extension, EENY-473, revised 2022)
8. Of mites found on 104 parasitized worker bees, 95.2% (99 mites) were on the underside of the abdomen, where the fat body lies. (Source: Ramsey et al., PNAS, 2019)
9. In feeding trials, 40% of mites fed fat body produced eggs, compared with 5% of mites fed hemolymph. (Source: Ramsey et al., PNAS, 2019)
10. In colonies with brood, uncontrolled mite populations can double monthly. (Source: Honey Bee Health Coalition, Tools for Varroa Management, 8th ed., 2022)

The Ramsey et al. survival and egg-laying figures come from small laboratory feeding trials (15 mites per diet), not field colonies.

Viruses

Viruses spread by Varroa, including deformed wing virus

Much of the damage Varroa does comes from the viruses it carries, and deformed wing virus is the best known of them.

1. Varroa destructor is a confirmed vector of 5 debilitating honey bee viruses and potentially 13 others. (Source: Ramsey et al., PNAS, 2019)
2. In the 2017-2018 national survey, deformed wing virus was found in 78.0% (787) of samples. (Source: USDA APHIS, National Honey Bee Disease Survey 2017-2018 summary, 2019)
3. Varroa destructor virus was the most common virus in the same survey, found in 80.7% (804) of samples. (Source: USDA APHIS, National Honey Bee Disease Survey 2017-2018 summary, 2019)
4. Israeli acute paralysis virus was found in 20.5% and Kashmir bee virus in 5.4% of 2017-2018 survey samples. (Source: USDA APHIS, National Honey Bee Disease Survey 2017-2018 summary, 2019)
5. In 2016 samples from 32 U.S. states, the DWV-A strain was present in 83% of 217 colonies and DWV-B in 56%. (Source: Kevill et al., Viruses, 2019)
6. The same study concluded that DWV-A was more virulent than DWV-B at the colony level. (Source: Kevill et al., Viruses, 2019)
7. USDA found high levels of deformed wing virus A and B and acute bee paralysis virus in all bees it sampled in February 2025 after large commercial losses. (Source: USDA ARS news release, June 2025)
8. In pooled 2025 samples from about 113 colonies in commercial operations, deformed wing virus was found in 78% and acute bee paralysis virus in 72%. (Source: USDA ARS-led preprint, bioRxiv, 2025)

Kevill et al. report some sample sizes differently in the abstract and the main text; only the U.S. prevalence figures that appear consistently are used here. The 2025 bioRxiv study is a preprint that had not completed peer review when released.

USDA NASS data

Share of U.S. colonies affected by Varroa, 2016-2026

Each year USDA NASS asks operations with five or more colonies what stressors affected their colonies in each quarter. Varroa has been the most reported stressor in every quarter from 2016 to mid-2026 for which NASS published figures.

1. Varroa mites affected 21.8% of U.S. colonies in January-March 2026 and 22.2% in April-June 2026, in operations with five or more colonies. (Source: USDA NASS, Honey Bee Colonies, August 2026)
2. Varroa mites affected 28.3% of U.S. colonies in January-March 2025, 26.3% in April-June, 22.2% in July-September and 25.4% in October-December 2025. (Source: USDA NASS, Honey Bee Colonies, August 2026)
3. In 2024, the Varroa share ranged from 29.5% (October-December) to 36.6% (April-June) of U.S. colonies. (Source: USDA NASS, Honey Bee Colonies, August 2025)
4. In 2023, Varroa was reported in 52.0% of U.S. colonies in April-June and 46.5% in October-December. (Source: USDA NASS, Honey Bee Colonies, August 2024)
5. Varroa was reported in 55.7% of U.S. colonies in July-September 2020. (Source: USDA NASS, Honey Bee Colonies, August 2021)
6. In April-June 2026, the next most reported stressor after Varroa was other pests and parasites, at 5.2% of colonies. (Source: USDA NASS, Honey Bee Colonies, August 2026)
7. U.S. operations with five or more colonies lost 454,890 colonies, or 16%, in January-March 2026. (Source: USDA NASS, Honey Bee Colonies, August 2026)
8. NASS lists April-June 2019 stressor figures as not available; a footnote says data collection for the July 2019 quarterly survey was suspended. (Source: USDA NASS, Honey Bee Colonies, August 2020)

These are beekeeper-reported shares of colonies affected, not mite counts or deaths. NASS revises earlier quarters: January-March 2024 was first published as 43.3% (August 2024) and revised to 31.8% (August 2025), and January-March 2025 went from 29.9% to 28.3%. The lower figures for 2024-2026 contrast with the high 2025 commercial losses reported by USDA ARS, so the NASS series should not be read as proof that the Varroa problem has eased.

Colony losses

Varroa's role in recent U.S. colony losses

In 2025 USDA scientists tied a wave of commercial colony collapses to viruses carried by mites that resist amitraz, the most widely used miticide.

1. USDA ARS reported in June 2025 that over 60% of commercial beekeeping colonies had been lost since the prior summer. (Source: USDA ARS news release, June 2025)
2. Those losses represented about 1.7 million colonies and an estimated $600 million financial impact. (Source: USDA ARS news release, June 2025)
3. USDA collected colony and bee samples in California and other western states in February 2025, before almond pollination. (Source: USDA ARS news release, June 2025)
4. USDA found signs of amitraz resistance in virtually all Varroa mites it collected in 2025. (Source: USDA ARS news release, June 2025)
5. The six commercial operations in the 2025 USDA study had a combined summertime high of 183,750 colonies, roughly 6.8% of U.S. managed colonies. (Source: USDA ARS-led preprint, bioRxiv, 2025)
6. U.S. beekeepers lost an estimated 55.6% of managed colonies from April 2024 to April 2025, including 40.2% over winter. (Source: Auburn University and Apiary Inspectors of America survey, 2025)
7. The 2024-2025 survey included 2,453 beekeepers managing 219,097 colonies, about 8.4% of U.S. honey-producing colonies. (Source: Auburn University and Apiary Inspectors of America survey, 2025)
8. Annual colony losses in 2024-2025 ranged from 34.3% to 90.5% among states. (Source: Auburn University and Apiary Inspectors of America survey, 2025)
9. Losses eased in 2025-2026 to 39.9% for the year, with 30.3% lost over winter, among more than 2,300 beekeepers managing 219,000 colonies. (Source: Auburn University news release, June 2026)

The Auburn/Apiary Inspectors of America survey is voluntary and measures losses over a full year, while USDA NASS reports quarterly losses for operations with five or more colonies, so their loss rates are not directly comparable. The 2025-2026 Auburn release names parasites and poor forage as pressures but does not give a Varroa-specific figure.

Monitoring

Treatment thresholds and how mites are counted

Beekeepers count mites per 100 adult bees and act when counts pass a threshold that depends on the season.

1. The Honey Bee Health Coalition's threshold for prompt control is above 1 mite per 100 bees during dormancy and above 2 to 3 mites per 100 bees during population increase. (Source: Honey Bee Health Coalition, Tools for Varroa Management, 8th ed., 2022)
2. The coalition's threshold for prompt control is above 3 mites per 100 bees at peak population and above 2 to 3 per 100 bees as the population declines. (Source: Honey Bee Health Coalition, Tools for Varroa Management, 8th ed., 2022)
3. A standard mite sample is about 300 bees, roughly half a cup of lightly packed bees. (Source: Honey Bee Health Coalition, Tools for Varroa Management, 8th ed., 2022)
4. The alcohol or soap wash and the powdered sugar shake are the two recommended methods; the sugar shake is less reliable because mite counts vary more. (Source: Honey Bee Health Coalition, Tools for Varroa Management, 8th ed., 2022)
5. The ether roll is rated unreliable because it detects only 50 to 60 percent of mites. (Source: Honey Bee Health Coalition, Tools for Varroa Management, 8th ed., 2022)
6. Sticky debris boards can track mite trends, with a suggested threshold of fewer than 10 mites falling per day. (Source: Honey Bee Health Coalition, Tools for Varroa Management, 8th ed., 2022)
7. In the 2017-2018 national survey, 89.5% of 947 alcohol samples were positive for Varroa. (Source: USDA APHIS, National Honey Bee Disease Survey 2017-2018 summary, 2019)
8. Positive samples in that survey averaged 3.37 mites per 100 bees. (Source: USDA APHIS, National Honey Bee Disease Survey 2017-2018 summary, 2019)
9. The 3-mites-per-100-bees damage threshold was exceeded in 31.7% (300) of all 2017-2018 survey samples. (Source: USDA APHIS, National Honey Bee Disease Survey 2017-2018 summary, 2019)
10. When left untreated, colonies with high mite levels may die within months. (Source: Honey Bee Health Coalition, Tools for Varroa Management, 8th ed., 2022)

Treatments

Miticides and the history of resistance

Varroa has become resistant to the three synthetic miticides beekeepers relied on most: tau-fluvalinate, coumaphos and now amitraz.

1. The Honey Bee Health Coalition lists widespread mite resistance to tau-fluvalinate, sold as Apistan. (Source: Honey Bee Health Coalition, Tools for Varroa Management, 8th ed., 2022)
2. The coalition cites extensive coumaphos-resistant mite populations in the United States and Canada; coumaphos is sold as CheckMite+. (Source: Honey Bee Health Coalition, Tools for Varroa Management, 8th ed., 2022)
3. As of 2022 the coalition noted some indications of resistance where amitraz (Apivar) had been used for several seasons. (Source: Honey Bee Health Coalition, Tools for Varroa Management, 8th ed., 2022)
4. Amitraz had been used to control Varroa in the United States for more than 20 years by 2020. (Source: Rinkevich, PLoS ONE, 2020)
5. A 2020 USDA study tested amitraz resistance in 11 commercial operations and 19 apiaries; mites could not be evaluated in 5 operations because too few were collected. (Source: Rinkevich, PLoS ONE, 2020)
6. In one apiary, Apivar killed 68% of mites overall, with efficacy ranging from 28% to 97% between colonies. (Source: Rinkevich, PLoS ONE, 2020)
7. Lower Apivar efficacy was significantly correlated with higher amitraz resistance in the 2020 study. (Source: Rinkevich, PLoS ONE, 2020)
8. In the USDA ARS-led preprint behind that finding, all 39 mites screened from five commercial operations carried amitraz-resistance genotypes. The study had not completed peer review. (Source: USDA ARS-led preprint, bioRxiv, 2025)

The 2025 amitraz genotype result covers only 39 mites and comes from a preprint (bioRxiv) that had not completed peer review; the preprint also describes the mites' colony sources inconsistently. It shows that resistance is present in the operations sampled but does not give a national rate.

Resistant stock

Bees bred to resist Varroa

USDA's Baton Rouge bee lab has spent decades breeding bees that hold mites down, including Russian, VSH and Pol-line stock. University researchers in Southern California are studying locally adapted hybrids.

1. Varroa-sensitive hygiene (VSH) is a behavior in which worker bees remove Varroa by expelling infested pupae. (Source: USDA ARS news release, 2022)
2. USDA ARS breeding for low Varroa populations began in the late 1990s, and ARS developed Pol-line bees from VSH stock in 2014. (Source: USDA ARS news release, 2022)
3. In a study in Mississippi, California and North and South Dakota, untreated Pol-line colonies had a 62.5% winter survival rate versus 3% for untreated standard colonies. (Source: USDA ARS news release, 2022)
4. When both types were treated in fall and December, Pol-line colonies had 72% winter survival and standard colonies 56%. (Source: USDA ARS news release, 2022)
5. In a USDA bioassay, Pol-line and VSH colonies removed roughly 80% of mite-infested pupae (15 Pol-line and 12 VSH colonies tested). (Source: Danka, Harris and Dodds, Apidologie, 2016)
6. USDA imported 100 queen honey bees from the Primorsky territory of Russia in 1997 to breed for mite resistance. (Source: USDA ARS Baton Rouge Honey Bee Lab)
7. USDA began releasing Russian honey bee stock to the industry in 2000. (Source: USDA ARS Baton Rouge Honey Bee Lab)
8. In Alabama trials from 2004 to 2006, 12% of VSH colonies, 24% of Russian colonies and 40% of Italian control colonies reached the Varroa treatment threshold. (Source: Ward et al., Journal of Economic Entomology, 2008)
9. Russian and VSH colonies produced honey yields comparable to Italian colonies in 2005 and 2006 in the same trials. (Source: Ward et al., Journal of Economic Entomology, 2008)
10. UC Riverside researchers monitored 236 Southern California colonies from 2019 to 2022 and found those headed by local Californian hybrid queens had about 68% fewer mites than colonies with commercial queens. (Source: UC Riverside news release, April 2026; Chong-Echavez and Baer, Scientific Reports, 2026)
11. The Californian hybrid colonies were more than five times less likely to cross the threshold at which chemical treatment becomes necessary. (Source: UC Riverside news release, April 2026)
12. In lab tests, mites were significantly less attracted to seven-day-old larvae of the Californian hybrid bees than to commercial larvae. (Source: Chong-Echavez and Baer, Scientific Reports, 2026)

None of these stocks is mite-proof. USDA says Russian bees are not immune, and UC Riverside says its Californian hybrids are not entirely mite-free and does not recommend abandoning current management. The 68% figure is from a university news release; the paper reports 68.3% lower mite intensity.

Wild colonies

Why feral and local colonies matter

When Varroa arrived, most unmanaged colonies died. Some wild populations have since persisted, and researchers are studying them as a source of mite tolerance.

1. Because feral colonies were not managed for Varroa, they were lost quickly as the mite spread. (Source: UF/IFAS Extension, EENY-473, revised 2022)
2. Cornell's Thomas Seeley studied feral colonies in the 1,651-hectare Arnot Forest from 2002 to 2005. (Source: Seeley, Apidologie, 2007)
3. Most Arnot Forest colonies found in fall 2002 were still alive in fall 2005, and their mite populations did not surge in late summer. (Source: Seeley, Apidologie, 2007)
4. Seeley concluded the stable bee-mite relationship in the Arnot Forest reflected low mite virulence rather than bee resistance. (Source: Seeley, Apidologie, 2007)
5. The UC Riverside hybrid bees come from a genetically mixed Southern California population, often from feral colonies living in trees. (Source: UC Riverside news release, April 2026)
6. That Southern California population carries ancestry from at least four honey bee lineages: African, Eastern European, Middle Eastern and Western European. (Source: UC Riverside news release, April 2026)

These findings come from specific populations (one New York forest, one Southern California study) and do not show that every wild colony tolerates Varroa.

Emerging threat

Tropilaelaps: the next mite to watch

Tropilaelaps is another Asian parasitic mite of honey bee brood. It is not known to be in North America, but it has been spreading.

1. As of 2024, Tropilaelaps mites were not known to be in North America. (Source: Honey Bee Health Coalition, Tropilaelaps primer, 2024)
2. Peer-reviewed studies have documented Tropilaelaps mercedesae in Western honey bee colonies in Georgia (the country), Russia and Uzbekistan. (Source: Honey Bee Health Coalition, Tropilaelaps primer, 2024)
3. Tropilaelaps's primary natural host is the giant Asian honey bee, Apis dorsata, and the mite is native to tropical and subtropical Asia. (Source: UF/IFAS Extension, EENY-604, revised 2022)
4. Each Tropilaelaps foundress lays about three to four eggs in a capped cell, and offspring develop from egg to adult within a week. (Source: UF/IFAS Extension, EENY-604, revised 2022)
5. In severe cases, Tropilaelaps can kill up to 50% of a colony's brood. (Source: UF/IFAS Extension, EENY-604, revised 2022)
6. Adult female Tropilaelaps are about 0.7 to 1.0 mm long, smaller and narrower than Varroa. (Source: UF/IFAS Extension, EENY-604, revised 2022)
7. No suspect Tropilaelaps mites were found in any brood samples in the 2017-2018 USDA APHIS national survey. (Source: USDA APHIS, National Honey Bee Disease Survey 2017-2018 summary, 2019)

The primer says registered Varroa products may control Tropilaelaps, but research on their efficacy is still under way.

Questions

Frequently asked questions

Keep reading

Related on this site

• Why are honey bees important (and why are they dying)?
• What happens to bees after a live removal
• Live bee relocation

How this page was made

Methodology & sources

Every fact on this page was traced to a primary source (a government data release, a university research or extension publication, a professional medical body or a peer-reviewed paper) and checked against the original document. Data years are given where they differ from publication years. Where reputable sources disagree, both figures are shown. Sources are named in plain text next to each fact.

• USDA National Agricultural Statistics Service (NASS), Honey Bee Colonies reports, 2017-2026
• USDA Agricultural Research Service (ARS)
• USDA ARS Honey Bee Breeding, Genetics and Physiology Laboratory, Baton Rouge
• USDA APHIS, National Honey Bee Disease Survey 2017-2018
• Ramsey et al., Proceedings of the National Academy of Sciences, 2019
• Kevill et al., Viruses, 2019
• USDA ARS-led preprint on bioRxiv, 2025
• Rinkevich, PLoS ONE, 2020
• Danka, Harris and Dodds, Apidologie, 2016
• Ward et al., Journal of Economic Entomology, 2008
• Seeley, Apidologie, 2007
• Chong-Echavez and Baer, Scientific Reports, 2026
• UC Riverside News
• Auburn University and Apiary Inspectors of America
• Honey Bee Health Coalition
• UF/IFAS Extension Featured Creatures (EENY-473, EENY-604)