Honey bee colonies face a range of pests, from parasitic mites that feed on developing brood to beetles and moths that destroy comb and ferment honey. The most damaging by far is the Varroa mite, responsible for more colony losses worldwide than any other single factor. But several other pests cause serious problems, and understanding what each one does helps you recognize infestations early and protect your hives.
Varroa Mites: The Most Destructive Pest
Varroa destructor is a reddish-brown parasitic mite about the size of a pinhead that has reshaped beekeeping since its global spread in the late 20th century. Its life cycle has two phases. During the dispersal phase, adult female mites cling to adult bees, hitching rides between colonies on drifting or robbing bees. During the reproductive phase, a female mite slips into a brood cell containing a five-day-old larva, hides beneath the larval food, and waits for the cell to be capped.
Once sealed inside, the foundress mite punctures the developing pupa’s skin and creates a feeding site for herself and her offspring. About 60 to 70 hours after capping, she lays her first egg (an unfertilized male), followed by two to five fertilized female eggs at roughly 30-hour intervals. The offspring mature in under a week and mate inside the cell before emerging with the adult bee. Drone cells are invaded about 12 times more frequently than worker cells because the longer development period gives more offspring time to mature and mate.
For years, researchers assumed Varroa fed primarily on bee blood (hemolymph). More recent work shows the mites actually target the fat body, a tissue critical for immune function, nutrient storage, and pesticide detoxification. The mite uses extra-oral digestion to dissolve fat body cells beneath the feeding site, then consumes the resulting material with a rapid pharyngeal pump. This fat body damage weakens individual bees and, just as critically, makes them far more vulnerable to viruses. Varroa is the primary vector for Deformed Wing Virus and several other pathogens that can collapse a colony.
Monitoring and Treatment Thresholds
The University of Minnesota Bee Lab recommends keeping Varroa levels below 1% year-round for the best survival odds, measured as zero to two mites in a 300-bee alcohol wash sample. Colonies above 2% (six or more mites per 300 bees) need treatment promptly. Monthly monitoring catches rising populations before they spiral out of control, since mite numbers can double roughly every month during brood-rearing season.
Treatments fall into two broad categories. Synthetic acaricides like amitraz can achieve around 94% mite kill, but repeated use has driven resistance in Varroa populations in many regions. Organic acids offer an alternative: formic acid-based treatments reach roughly 88% efficacy and have the unique advantage of penetrating capped brood cells where mites reproduce. Because formic acid occurs naturally in honey, resistance is far less likely to develop. Formic acid treatments work best between about 10°C and 29°C (50°F to 85°F), where the gel formulation volatilizes gradually without spiking to dangerous concentrations.
Small Hive Beetle
The small hive beetle (Aethina tumida) is a dark, oval beetle roughly a third the size of a honey bee. Adults are a nuisance, but the larval stage does the real damage. Female beetles lay eggs in cracks and crevices inside the hive, and the larvae that hatch are voracious feeders for five to eight days, consuming pollen, brood, honey, dead bees, and comb. As they feed, they introduce yeasts that ferment the honey, causing it to bubble and run out of the comb. The result is a slimy, foul-smelling mess that bees abandon.
Strong colonies can often corral beetles into corners and keep them in check, but weak colonies or unattended stored equipment are highly vulnerable. Even strong colonies can be overwhelmed during heavy beetle pressure. Placing hives in full sun helps, since beetles prefer shade and moisture. Freezing drawn comb before storage kills any eggs or larvae present. Inside the hive, crushing visible adult beetles and using beetle traps reduces populations without chemicals.
Wax Moths
Greater wax moths (Galleria mellonella) rarely threaten strong, healthy colonies because the bees actively patrol and remove moth larvae. The real danger is to weak colonies and stored equipment. Adult moths lay eggs in the hive, and the larvae immediately begin burrowing through comb, lining their tunnels with thick silk webbing. They consume beeswax, pollen, and cocoon remnants left in brood cells.
The signs are distinctive. Look for silk-lined tunnels running through the comb, dark cylindrical droppings on the bottom board, and a condition called “bald brood,” where moth larvae tunneling just beneath cell caps cause worker bees to chew away the remaining wax and expose the heads of developing pupae. This exposure can lead to deformed legs or wings in the emerging bees. In stored equipment, moth cocoons harden between frames and can fuse an entire box of combs into an unusable block.
Prevention centers on proper storage. Keep unused equipment in areas with good ventilation, low humidity, and bright light, all conditions wax moths avoid. Freezing comb for 48 hours kills all life stages. In active hives, maintaining strong colony populations is the single best defense.
Tracheal Mites
Tracheal mites (Acarapis woodi) are microscopic parasites that live inside the breathing tubes of adult bees. Unlike Varroa, they don’t cause sudden, dramatic collapses. Instead, they shorten an individual bee’s lifespan by a few days, which translates to roughly a 5% reduction in colony population over time. Colonies that develop heavy infestations typically do so in late summer and die during late winter, when the population is already under stress and can’t replace lost bees quickly enough.
Tracheal mites were once a major concern, particularly when they first arrived in North America in the 1980s. Since then, many bee populations have developed partial resistance, and the pest has faded as a primary threat in most managed apiaries. British bee strains and certain North American lines show meaningful resistance. Formic acid treatments used for Varroa also help control tracheal mites, so beekeepers managing for Varroa often suppress tracheal mites as a side benefit.
Tropilaelaps Mites: A Growing Concern
Tropilaelaps mercedesae is a brood-feeding mite native to tropical and subtropical Asia, where it parasitizes giant honey bees. Over the past 50 years, its range has expanded, and researchers are increasingly concerned about its potential introduction to North America and Europe. It has not arrived yet, but global trade in bees and bee products creates ongoing risk.
Tropilaelaps is in some ways more dangerous than Varroa. The mites reproduce faster because they skip the extended feeding period on adult bees that Varroa requires. A foundress mite emerges from one brood cell and can immediately enter another to lay eggs. Each foundress produces one to four eggs per cell, with a sex ratio of about one male to three females. Offspring mature in roughly a week. This rapid turnover means Tropilaelaps populations grow extremely quickly once established.
Their main limitation is a dependence on brood. Tropilaelaps mites have small mandibles that can only pierce soft larval tissue, not adult bee skin, so they cannot survive long without access to brood. They can last about three days in dry pollen and six days in empty honeycomb, but extended broodless periods kill them. This biological constraint has so far limited their spread to regions with year-round brood production, though recent research suggests they may survive broodless periods by scavenging food from dead bees or during bee-to-bee feeding. If they adapt to temperate climates with seasonal brood breaks, the consequences for beekeeping could be severe.
Integrated Pest Management for Beekeepers
Effective pest control in a beehive combines cultural, physical, and mechanical strategies rather than relying on chemicals alone. Cultural controls disrupt the pest’s preferred environment. Placing hives in full sun discourages small hive beetles. Keeping colonies strong and well-nourished helps bees defend against wax moths. Using Varroa-resistant bee stock, such as lines bred for hygienic behavior that detects and removes infested brood, reduces mite loads without any chemical input.
Physical controls exploit a pest’s biological limitations. Freezing stored comb eliminates wax moth and small hive beetle larvae. Storing equipment with good ventilation and light deters wax moth egg-laying. Mechanical controls directly reduce pest numbers: screened bottom boards allow Varroa mites that fall off bees to drop out of the hive rather than climbing back onto a host, and drone brood removal takes advantage of Varroa’s strong preference for drone cells by letting bees build drone comb, then removing and freezing it once capped, pulling large numbers of reproducing mites out of the colony.
Chemical treatments remain necessary for Varroa in most operations, but rotating between synthetic and organic options slows resistance development. The goal is never zero mites, which is unrealistic in any environment where colonies interact. The goal is keeping mite levels below the damage threshold through regular monitoring and timely intervention.