Acarapiosis in Honey Bees: Tracheal Mite Infection and What to Watch For
- Acarapiosis is a tracheal mite infection caused by Acarapis woodi, a microscopic parasite that lives inside the breathing tubes of adult honey bees.
- Common warning signs at the colony level include weak overwintered colonies, bees crawling near the entrance, poor flight, and wings held in a "K-wing" position, but these signs are not specific.
- A true diagnosis requires microscopic examination of dissected tracheae. Looking at the colony from the outside is not enough to confirm the problem.
- Early action matters most when colonies are weak in late winter or spring. Your vet, apiary inspector, or bee diagnostic lab can help rule out tracheal mites versus Varroa, pesticide exposure, or starvation.
- Management often combines supportive colony care, resistant bee stock, and label-directed mite control when appropriate.
What Is Acarapiosis in Honey Bees?
Acarapiosis, also called tracheal mite disease, is caused by the mite Acarapis woodi. This parasite lives inside the prothoracic tracheae, the breathing tubes of adult honey bees. Unlike Varroa mites, tracheal mites are not easy to see on the outside of a bee.
The mites feed and reproduce inside the airways, which can damage the tracheal lining and interfere with normal respiration and activity. Heavy infestations have been linked with reduced honey production and poorer winter survival, especially when a large share of the colony's adult bees is affected.
For pet parents who keep bees, the tricky part is that acarapiosis can look like several other colony problems. A weak spring colony, crawling bees, or poor flight may raise concern, but those signs can also happen with Varroa-related disease, pesticide exposure, queen issues, or nutrition problems. That is why confirmation matters before making a treatment plan.
Symptoms of Acarapiosis in Honey Bees
- Bees crawling near or in front of the hive entrance
- Poor flight or bees unable to take off normally
- Wings held apart in a "K-wing" position
- Weak colony growth or failure to thrive after winter
- Higher winter losses or poor overwinter survival
- Reduced honey production
See your vet immediately if your colony is crashing, large numbers of bees are crawling or dying, or you suspect pesticide exposure, starvation, or a reportable bee disease. Tracheal mite signs are suggestive, not definitive. Because colony-level symptoms overlap with other serious problems, a weak or failing hive should be evaluated promptly with hands-on inspection and, when needed, lab testing.
What Causes Acarapiosis in Honey Bees?
Acarapiosis is caused by infestation with Acarapis woodi, a mite that affects adult honey bees only. Young adult bees are especially vulnerable because mites move onto them and enter the tracheae, where they feed and reproduce. Overwintering bees can carry multiple generations of mites within a single bee.
Spread usually happens through close contact between bees. Drifting, robbing, package bees, swarms, and movement of colonies or queens can all help mites move between hives. Stressors such as poor nutrition, harsh winter conditions, and other parasite burdens may make the impact of infestation more noticeable.
Not every colony with tracheal mites becomes severely ill. Genetics matter. Some bee stocks show better resistance, likely in part because of grooming behavior and other inherited traits that reduce infestation pressure. That is one reason your vet or bee health advisor may talk with you about both immediate management and longer-term stock selection.
How Is Acarapiosis in Honey Bees Diagnosed?
Acarapiosis cannot be confirmed by symptoms alone. A positive diagnosis requires microscopic examination of the tracheae from adult bees. In practice, this means collecting a sample of bees, dissecting the thorax, and evaluating the tracheal tubes for discoloration, scarring, lesions, or visible mites under magnification.
Healthy tracheae are typically clear and transparent. Infested or damaged tracheae may look darkened, scarred, or blotchy. Because other Acarapis species can occur on bees externally, the location of the mite matters: Acarapis woodi lives exclusively in the prothoracic tracheae, which helps confirm the diagnosis.
Sampling is often most useful in early spring or when symptoms first appear. Your vet may recommend working with a state apiary inspector, university bee lab, or diagnostic service. In the United States, sample testing commonly falls around $25-$40 per sample, while on-site hive consultation or inspection may add $65-$150+ depending on travel, region, and the number of colonies involved.
Treatment Options for Acarapiosis in Honey Bees
Spectrum of Care means you have options. Here are treatment tiers at different price points.
Budget-Conscious Care
- Hands-on colony assessment
- Diagnostic sampling before treatment
- Supportive management to keep colonies populous
- Nutrition review and correction of obvious stressors
- Monitoring rather than immediate chemical treatment when signs are mild or uncertain
Recommended Standard Treatment
- Microscopic confirmation or strong evidence-based suspicion
- Label-directed menthol treatment when appropriate
- Timing treatment outside heavy nectar flow
- Removal of honey supers as required by label
- Follow-up colony checks and seasonal management adjustments
Advanced / Critical Care
- Comprehensive apiary consultation
- Multiple diagnostic samples across hives
- Requeening with resistant stock
- Splitting, combining, or depopulating severely affected colonies when advised
- Integrated mite and stressor management plan for the whole apiary
Cost estimates as of 2026-03. Actual costs vary by location, clinic, and individual case.
Questions to Ask Your Vet About Acarapiosis in Honey Bees
Bring these questions to your vet appointment to get the most out of your visit.
- Do my bees' signs fit tracheal mites, or are Varroa, starvation, queen failure, or pesticides more likely?
- What sample size do you want for tracheal mite testing, and where should I send it?
- Are the tracheae changes severe enough to explain this colony's weakness?
- Is treatment appropriate right now based on temperature, nectar flow, and whether honey supers are on the hive?
- What supportive steps can help this colony recover besides mite treatment?
- Should I requeen with more resistant stock if this problem keeps returning?
- Do nearby colonies need to be checked too, even if they look normal?
- What follow-up timeline do you recommend to see whether the colony is improving?
How to Prevent Acarapiosis in Honey Bees
Prevention starts with strong colony management. Keep colonies well fed, reduce avoidable stress, and monitor weak hives closely after winter. Tracheal mite problems are often most noticeable when bees are already under pressure from weather, nutrition gaps, or other parasites.
Use resistant stock when possible. Research from USDA has shown that some honey bee lines have inherited resistance traits that help reduce tracheal mite infestation. Requeening chronically affected colonies with resistant queens can be part of a practical long-term plan.
Good biosecurity also matters. Avoid moving weak or questionable colonies without evaluation, be cautious when bringing in new bees, and work with reputable suppliers. If one colony shows suspicious signs, consider checking nearby hives too.
If your vet recommends treatment, use only EPA-registered, label-directed products and follow timing rules carefully. In the United States, menthol remains the specifically labeled option cited by USDA for tracheal mite control, and treatment timing depends on temperature and honey-flow conditions. Prevention is usually most effective when it combines monitoring, stock selection, and seasonally appropriate management rather than relying on one step alone.