Glossary
A microscopic internal mite (Acarapis woodi) that infests the tracheae (breathing tubes) of adult honey bees. Unlike varroa mites, which feed externally, tracheal mites live inside the bee's respiratory system, piercing the tracheal walls to feed on hemolymph (bee blood) and reducing the bee's ability to breathe and fly.
Tracheal mites are microscopic (approximately 150 micrometers) and can only be detected by dissection and microscopic examination of bee tracheae. Female mites enter the first thoracic spiracle (breathing pore) of young bees (under 4 days old), crawl into the tracheal tubes, and lay eggs. Multiple generations develop inside the tracheae, eventually blocking airflow.
Heavily infested bees have reduced flight ability, shortened lifespans, and difficulty thermoregulating. Colony-level effects include reduced honey production, poor overwintering survival, and increased susceptibility to other stressors. Tracheal mites caused significant colony losses in the 1980s and 1990s before effective management strategies were developed.
Tracheal mites have become much less problematic since the introduction of varroa-resistant bee stocks, many of which also show resistance to tracheal mites through grooming behavior. Menthol crystals placed on top bars are the traditional treatment, creating vapors that kill mites inside the tracheae.
Grease patties (vegetable shortening mixed with sugar) placed on top bars disrupt the mite's ability to find young bees. The grease coats the bees' bodies, masking the chemical signals that female mites use to identify suitable hosts. This prophylactic approach reduces infestation levels throughout the season.
Definitive diagnosis requires dissecting bees and examining their tracheae under a microscope. Healthy tracheae are clear and translucent. Infested tracheae appear darkened, stained, or blocked by mite bodies. State apiary inspectors can often perform this diagnosis.
Tracheal mites are much less problematic than in the 1980s-90s. Modern bee stocks often have genetic resistance. Varroa mite management has taken center stage as the primary parasitic concern. However, tracheal mites still cause occasional losses, particularly in colonies with susceptible genetics.
Some overlap exists. Formic acid vapor can reach mites inside tracheae. Menthol (used as a specific tracheal mite treatment) has some activity against varroa. However, most varroa treatments (Apivar, oxalic acid) do not significantly affect tracheal mites.
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