Tracheal Mites

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Tracheal mites, scientifically known as acarapis woodi, are microscopic pests of adult honey bees. These tiny pests infiltrate the respiratory system (tracheal tubes) of honey bees making it difficult for them to breathe. A tracheal mite infestation endangers colony survival as more and more adult bees become infected. Here, we explore some basics about tracheal mites in beehives and the danger they pose for our hives.

Microscopic tracheal mites in breathing tubes of honey bee.

Today, tracheal mites are not as feared as they once were. However, there was a time when this honey bee pest was considered a lethal problem. And still, beekeepers should be aware than an outbreak can occur in their area.

Understanding Tracheal Mites & Bees

The honey bee tracheal mite was first described in the early 1920’s. It was believed to be the main factor in “Isle of Wight Disease” (an epidemic resulting in many colony deaths in that area). However, later research seems to indicate that these mites were not the causative factor.

They were reported in Mexico in 1980. By 1984 colonies in Texas were discovered to be infested. To realize how tracheal mites affect honey bee colonies, you must understand a bit about their life cycle.

First, the female enters the breathing tubes of a honey bee. Unlike varroa mites, they are internal pests – you can’t see them.

Inside the bee trachea, the female lays eggs. These eggs hatch into “nymphs” which grow and go through several molts during their stages of development.

Both males and females are present but the majority are female. After mating, they leave the airway to look for another host.

They do have an age preference – seeking out adult honey bees that are less than 4 days old. Older honey bees are not nearly as attractive as a host.

Tracheal mites are highly adapted to their host “Apis mellifera species” and exist everywhere you find the bees. However, the presence and level of mite infestations varies by season and location.

Effects on Bee Colonies

The honey bee tracheal mite can have profound effects on the health and productivity of colonies. They obstruct and damage the breathing tubes of the bee’s respiratory system. This causes labored breathing, reduced oxygen intake, and increased carbon dioxide levels within the bee’s body.

Infestations can also shortened bee longevity. Individual honey bees do not live as long when suffering from Tracheal mites. This reduced life span causes drops in colony populations and a reduced workforce.

Weakened immune systems are also a common effect of bees fighting tracheal mites. They may succumb to infectious diseases and other pathogens that exist in the colony environment.

Sick individuals leads to a decline in overall colony health. If over 30% of the bees become parasitized, honey production falls and the colony is less likely to be able to overwinter.

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Symptoms & Diagnosis

There is no one observable symptom of a bee colony with Tracheal mites. Many of these conditions can be caused by other factors. So, it tends to be a bit of a guessing game or process of elimination.

Look for deformed or discolored wings on young bees. Infected bees may have wings that appear to be darker than healthy individuals. Wings may also be shortened, disjointed or deformed.

Slow colony buildup in the Spring beehive is possible, as well as, abnormal clustering in the hive during Winter.

Reduced foraging may be present. Bees may be found crawling near the entrance (unable to fly) as they find flying difficult due to breathing problems. Detecting tracheal mites is more likely in the Fall and Winter when bee populations are lower.

Beekeepers can collect and submit bee samples to the USDA-ARS for testing.

Wiki commons image of tracheal mite inside the breathing tubes of a honey bee.

Detection

The only true way to diagnose honey bees with tracheal mites is by dissection and viewing under a microscope. Which needless to say means the bee is killed and the tracheal tubes inspected for mites or mite damage.

Normal bee trachea are clear or pale in color. A bee with mite infestations will have dark, crusty lesions visible inside the breathing tubes.

Treatment

There are a few options for tracheal mite treatments in addition to buying bees that show some resistance (Buckfast bees) to the mite.

  • menthol
  • vegetable shortening patty
  • chemical miticides

Menthol

Menthol is currently the only EPA (Environmental Protection Agency) approved material to be used in controlling Acarapis woodi. However, the effectiveness of this treatment is dependent on: temperature, formulation, dosage, colony size, etc.

Colonies are treated in early Spring or late Fall – when no honey supers are on the hive and daytime temperatures are still above 60°F.

Menthol crystals (1.8 ounce) in a screened bag are placed in the colony for 20-25 days. Place menthol on the top bars as long as the daytime temperature does not exceed 80°F. Before using menthol, read and follow the approved label carefully.

Vegetable Shortening Patty

Local beekeepers have experienced good results by using a vegetable shortening sugar patty for tracheal mites. It is believed to distort the mites ability to find host bees of the optimal age.

The patty is made by mixing 2 part granular sugar with one part vegetable shortening (Crisco). A burger sized patty on wax paper is placed on the top bars of the brood box.

I have not seen any reason to treat for tracheal mites in recent years. However, in the past – I used the grease patty method.

It seems to work (or at least not hurt) – but it sure is messy during hot weather and can make hive inspections a pain.

Chemical Treatments

By chance, some of the popular varroa mite treatments can also help control tracheal mites. Formic Acid – marketed as Mite-Away II is one. The various thymol treatments (like Apiguard) offer some control as well.

FAQs

What are tracheal mites and how do they affect honey bee colonies?

Tracheal mites are microscopic parasites that infest the respiratory system of honey bees. They cause the bees to have difficulty breathing and have an overall decline in health.

What are the symptoms of Tracheal Mite infestations?

Symptoms of tracheal mite infestation includes bees with discolored or deformed wings, increased rates of bee mortality, and reduced foraging activity. Beekeepers may also notice bees crawling near hive entrances, as they struggle to fly due to respiratory impairment

Are tracheal mites a common problem for honey bee colonies?

Tracheal mites can be a significant problem for honey bee colonies, especially in regions with temperate climates. However, their prevalence and impact can vary depending on factors such as hive health, beekeeping practices, and environmental conditions.

Can tracheal mites spread between honey bee colonies?

Tracheal mites primarily spread within colonies through direct contact. They also can be transmitted through robbing bees or drifting bees.

Final Thoughts

Tracheal mite infestations are not a major problem for most US beekeepers today. At least not to the degree of continued varroa mite treatments that can not be overlooked. However, if you suspect that tracheal mites are damaging your colonies take action. Consult local beekeepers associations to learn if others in the region are having problems and consider a menthol treatment.

It is your responsibility to read the label and follow directions for any type of chemical treatment you place in your hives.

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