BEE MITES / ACARAPIS WOODI
The hidden mite inside a bee’s breathing tubes.
A detailed guide to Acarapis woodi: recognition limits, life cycle, laboratory diagnosis, winter impacts, resistant bees, treatment research and direct evidence on heat.
Expanded October 31, 2026 · 17 linked research sources and guidance documents
A mite inside the breathing tubes
Acarapis woodi is a microscopic parasite of adult honey bees. Females are approximately 0.15 mm long, far smaller than a readily visible adult Varroa female. The mite lives and reproduces in the tracheal system, especially the large prothoracic breathing tubes. [1] [3]
Examine the breathing tubes to confirm the infestation.
Transmission takes place between adult bees.
Colony symptoms guide investigation; they do not identify the mite by themselves.
Other Acarapis species occur externally on bees. A tiny mite found on the body is therefore not automatically A. woodi. The site on the host and appropriate diagnostic methods matter. [1] [6]
Distribution and why local testing matters
Tracheal mites have been reported in Europe, the Americas and parts of Asia. Their local prevalence and impact differ between populations and periods; a published detection record is not a live global map. The COLOSS methods paper describes this uneven knowledge, while more recent regional work illustrates the continuing role of molecular diagnosis. [3] [7]
| Research setting | Useful lesson |
|---|---|
| New York overwintering colonies | Cold-season colony outcomes can be associated with infestation. [9] |
| Japanese honey bees | Different bee hosts and seasonal treatment conditions deserve explicit attention. [13] |
| Regional molecular surveys | Diagnostic sampling can reveal findings that symptoms or casual observation miss. [6] [7] |
Life cycle and transmission
A dispersing female moves onto another bee and enters through a respiratory opening. Eggs and developing mites occur within the breathing tubes; mature females can leave to find another host. Host age and season influence the pattern of infestation and reproduction. [4]
Transfer
Adult-bee contact offers a route to a new host.
Development inside the bee
The mite population develops within the tracheae.
Dispersal
Females leave to find another suitable bee.
Feeding damages the tracheal walls, and infestation can interfere with bee function and survival. Life-history studies and mortality experiments help distinguish the effects on individual bees from the later performance of the colony. [1] [4] [8]
Symptoms: useful clues, not a diagnosis
| Possible observation | How to interpret it |
|---|---|
| Crawling or flight-impaired bees | Investigate tracheal mites alongside other causes of adult-bee impairment. |
| Disjointed or “K-wing” appearance | Can occur in affected bees, but does not establish tracheal-mite infestation. |
| Weakening or poor winter survival | Assess parasites, viruses, food and other colony conditions rather than assigning one cause from appearance. |
| Apparently normal bees | Visual normality does not exclude internal infestation. |
USDA describes the lack of one defining symptom. The New York overwintering study provides field evidence of negative colony effects in its investigated setting. [1] [9]
How to obtain a useful test
- Contact the diagnostic service first. Ask which bees to collect, the required number and how to preserve and ship them.
- Record the colony context. Note symptoms, date, colony strength, recent treatments and other mite results.
- Request the appropriate examination. Microscopic dissection examines the tracheae; validated molecular methods provide another diagnostic route.
- Ask how to interpret the result. The proportion of sampled bees infested and the intensity within individual bees answer different questions.
For microscopic examination, UF/IFAS provides an illustrated dissection protocol, also linked in the research library below. PCR research addresses species-targeted detection. [2] [6]
A Varroa wash does not examine the breathing tubes
An adult-bee wash counts external mites recovered by that procedure. It is not a substitute for examining the tracheae when Acarapis woodi is suspected.
The shared mite-identification guide helps place the different tests in context.
Control: confirm the target, then choose the method
| Approach | What the evidence contributes |
|---|---|
| Menthol | Field research includes seasonal efficacy, winter outcomes and residues. Product directions and the bee host matter. [13] |
| Formic-acid and other miticide studies | Trials have examined activity against A. woodi alongside Varroa, including the influence of vapor delivery and weather. [14] |
| Resistant bee stock | Breeding and population studies show variation in resistance to becoming infested. [10] [11] |
| Colony management and bee movement | Good records, diagnosis and movement advice help manage both the colony and spread between colonies. [3] [17] |
| Thermal research | Direct experiments support heat susceptibility, with specific temperatures, durations and bee settings. [5] |
Historical treatment descriptions are research context. For current use, verify that the actual product and application are permitted for the target mite in your location, and follow the label. A research dose or a treatment for a different mite is not a substitute for those directions.
Heat evidence: direct research exists
Harbo’s 1993 study is directly relevant to Acarapis woodi. It compared white and dark hives in a sunny field setting and also tested bees in laboratory exposures. The laboratory work showed that heat could affect mites while they were inside living bees. [5]
| Part of the study | Reported observation | What it means |
|---|---|---|
| White versus dark hives | The warmer dark hives had fewer tracheal mites later in the field comparison. | Supports an association between the hive thermal environment and infestation. |
| Laboratory heat exposure | A single six-hour exposure at 42°C significantly reduced mite populations. | Direct evidence for thermal susceptibility under the tested conditions. |
| Colony production | White hives produced more brood and honey during part of the comparison. | Colony performance belongs alongside mite measurements when interpreting the field result. |
The useful next comparison is a controlled exposure. Measure temperature and time, confirm infestation by dissection or a suitable assay, and compare subsequent mite and bee outcomes with untreated controls. Naturally sun-heated hive colors do not deliver the same controlled conditions as a regulated treatment.
For background on the wider thermal literature, use our heat-research library and the bee, brood and queen guide. The Harbo study below is the direct tracheal-mite source.
Why some bee populations resist infestation
Grooming can remove a dispersing mite before it enters the respiratory system. Danka and Villa tested the importance of that behavior by altering bees’ ability to groom and comparing resistant and susceptible stock. [10]
Other studies examine resistant populations, developmental temperature, differences between bee species and pesticide effects on grooming. Together they show why “resistance” is a trait to evaluate in a particular stock and environment, rather than a promise that every colony from a named group is mite-free. [11] [12] [15] [16]
A useful action checklist
- Assess the colony’s food, strength, brood and adult-bee signs.
- Keep external-Varroa results and tracheal-mite results separate.
- Obtain diagnostic advice and an appropriate sample.
- Choose a permitted control for the confirmed problem.
- Record the application, conditions and subsequent test or colony outcome.
- Follow local guidance before moving affected bees or queens.
Common questions
Does K-wing prove tracheal mites?
No. It is one possible sign, with other explanations. Examination of the breathing tubes or a suitable laboratory test addresses the mite question. [1] [2]
Can Varroa and tracheal mites occur together?
They occupy different locations and require different measurements. Finding one problem does not make a test for the other unnecessary when there are reasons to investigate it.
Has heat been studied specifically against tracheal mites?
Yes. Harbo’s work included field observations and laboratory exposures of infested bees. The tested conditions and measured outcomes are summarized above. [5]
Does a low Varroa wash result exclude tracheal mites?
No. It is a result for external mites in that sample, not an examination of the internal tracheal system.
Our collected research library
17 linked publications, study records and guidance documents. The label on each entry identifies its evidence type. Links lead to the original publication, an indexed study record or the responsible agency. Use the tested species, host and conditions when comparing results.
USDA ARS — Tracheal mite biology and diagnosis
Describes A. woodi, its position inside the bee and diagnosis by examining the tracheae. Historical treatment statements should be checked against current product labels.
UF/IFAS — Dissecting honey bees to detect tracheal mites
A practical illustrated dissection guide for examining the breathing tubes and recognizing infestation-related changes.
Sammataro et al. (2013) — Standard methods for tracheal mite research
COLOSS methods covering collection, identification, infestation measurement, damage assessment and control research. A foundation for comparing study designs.
Pettis & Wilson (1996) — Life history of the honey bee tracheal mite
Follows reproduction within bees over their life spans and across seasons. Connects host age with mite population development.
Harbo (1993) — Heat and mortality of tracheal mites
Field hive-color comparisons and laboratory experiments showed an association with heat and mite reduction. A six-hour exposure at 42°C significantly reduced mite populations.
Kojima et al. (2011) — PCR-based detection of Acarapis woodi
Develops species-targeted molecular detection. Relevant to laboratory confirmation and differentiating tiny mites that are difficult to identify visually.
PCR-based detection of Acarapis woodi in Türkiye (2023)
A regional investigation using microscopy and molecular methods. A detection record describes its sampled area and time, rather than the complete global distribution.
Honey bee mortality due to tracheal mite parasitism (1990)
Investigates the effect of parasitism on bee mortality and the challenges of documenting that effect from observed mite distributions.
Effects on overwintered honey bee colonies in New York (1992)
Field evidence connecting tracheal-mite infestation with adverse colony outcomes in a cold-winter region.
Danka & Villa (1998) — Autogrooming as resistance to tracheal mites
Tests the role of grooming by comparing resistant and susceptible bees when their ability to groom is altered.
Resistance to Acarapis woodi in bees from far-eastern Russia
Investigates resistance in a distinct bee population. Supports considering the source and documented traits of replacement stock.
McMullan & Brown (2006) — Pupation temperature and autogrooming
Examines how developmental temperature and grooming relate to susceptibility. This is not the same experiment as treating an infested adult colony with heat.
Maeda & Sakamoto (2016) — Menthol in Japanese honey bees
Tests seasonal efficacy, winter outcomes and honey residues in A. cerana japonica. Results belong to that host, method and management setting.
Miticide evaluation and formic-acid vapor conditions (2001)
Evaluates treatments for Varroa and A. woodi in Tennessee colonies. Shows why delivery conditions, weather and colony effects matter alongside mite reduction.
Differential autogrooming in Apis cerana and Apis mellifera
Compares the grooming response to tracheal mites between bee species. A useful companion to within-species breeding and resistance work.
Effects of neonicotinoids on autogrooming against tracheal mites
Investigates an interaction between pesticide exposure and a behavior used to resist infestation. Links parasite defense with wider bee-health management.
WOAH — Infestation of honey bees with Acarapis woodi
Defines the infestation and provides international movement and biosecurity context. Consult the current national authority for local requirements.
Shared guides & research
Start with these guides when you need to identify a mite, compare species or understand treatment evidence. Use the mite-specific information on this page to choose the appropriate tests and controls.