The most damaging parasite of honey bees worldwide is Varroa destructor, the varroa mite. These mites feed on bee fat bodies and transmit a suite of viruses that weaken and eventually kill colonies if left unchecked. A commonly used treatment threshold is roughly 3 mites per 100 bees, although specific recommendations vary. Beekeepers monitor varroa levels using methods such as the alcohol wash, sugar roll, and sticky board counts, and they treat infestations with a combination of acids like oxalic and formic acid, essential oils such as thymol, synthetic acaricides like amitraz, and mechanical approaches such as drone brood removal. Integrated pest management combines biological, mechanical, and chemical strategies to keep mite populations below damaging levels.
Other pests and diseases add to the challenge. The small hive beetle, an African pest, fouls honey and weakens colonies when it becomes established. Tracheal mites, microscopic parasites of bee airways, are now less common thanks to resistant stock. Among bacterial diseases, American Foulbrood (AFB) is the most devastating; its spores can persist for decades, and many jurisdictions require infected colonies to be destroyed by burning. European Foulbrood (EFB) is less severe. Nosema is a microsporidian gut disease, chalkbrood is a fungal infection of larvae, and deformed wing virus (DWV), often spread by varroa, is widespread and damaging. The phenomenon known as colony collapse disorder, in which worker bees abandon the hive, is now understood to have multiple interacting causes including parasites, pathogens, pesticides, poor nutrition, and environmental stressors. Neonicotinoid pesticides have been particularly implicated in pollinator declines.
Defensive stinging is part of keeping bees. A honey bee's barbed stinger typically detaches in mammalian skin, fatally wounding the bee, which is why honey bees usually die after stinging humans. For first aid, the stinger should be scraped out rather than pinched, the area iced, and an antihistamine taken; anyone showing signs of anaphylaxis, a severe life-threatening allergic reaction, requires immediate epinephrine. Distinguishing bees from wasps helps with both safety and identification: bees are typically hairy and vegetarian, while wasps are slimmer and often carnivorous and aggressive.