Pests and Diseases

Honey bee diseases and pests: a practical guide: 

Quick Reference guide:


Honey Bee Pests

Honey Bee Diseases (below)

Queen honey bee

A healthy honey bee colony has three distinct types of individuals: queen, worker, and drone. The queen is an especially important individual in the colony, as she is the only actively reproductive female and generally lays all the eggs.

Healthy C-shaped larvae

It is important to be able to identify healthy brood stages. Healthy worker, queen, and drone larvae are pearly white in color with a glistening appearance. They are curled in a “C” shape on the bottom of the cell and continue to grow during the larval period, eventually filling their cell.

A healthy worker brood pattern is easy to recognize: brood cappings are medium brown in color, convex, and without punctures. Healthy capped worker brood normally appears as a solid pattern of cells with only a few uncapped cells; these may contain eggs, uncapped larvae, nectar, or pollen.

Honey Bee Parasites, Pests, and Predators

Varroa mite (Varroa destructor)

The varroa mite is considered by many to be the most serious malady of honey bees. It now occurs nearly worldwide. This external parasite feeds on the hemolymph (blood) of adult bees, larvae, and pupae.

Honey bee tracheal mite (Acarapis woodi)

A second mite that infests honey bees is the honey bee tracheal mite. This internal parasitic mite lives within the tracheae, or breathing tubes, inside the thorax of adult honey bees. Tracheal mites also may be found in air sacs in the thorax, abdomen, and head. The mites pierce the breathing tube walls with their mouth parts and feed on the hemolymph, or blood, of the bees.

Small hive beetle (Aethina tumida)

The small hive beetle, North America’s newest beekeeping pest, was first identified in Florida in the spring of 1998. This pest originated in Africa. The adult beetle is small (about one-third the size of a bee), black or brown, and covered with fine hair. The larvae are small, cream-colored grubs without prolegs.

Bee louse (Braula coeca)

Braula coeca, commonly known as the bee louse, actually is a wingless fly. The adults are small (slightly smaller than the head of a straight pin), and reddish-brown in color. Although several adult flies may live on a queen, usually only one will be found on a worker. These pests apparently do little harm.

Larval greater wax moth (Galleria mellonella)

Larvae of the greater wax moth cause considerable damage to beeswax combs left unattended by bees. Beeswax combs in weak or dead colonies and those placed in storage are subject to attack. Wax moths pose a continuous threat except when temperatures drop below 40oF.

Spiders, earwigs, and cockroaches

Beehives provide shelter to a number of large and small arthropods such as spiders, earwigs, and cockroaches. These are not harmful to the bees or hive equipment and do not require control.


Ants usually are not serious pests in honey bee colonies. Occasionally, however, certain species may enter colonies to search for food or establish nesting sites. Ants typically are found between the inner and outer covers of the hive and in pollen traps. Although ants seldom disturb the bees, they can be a nuisance to the beekeeper.


Mice are a serious pest of stored combs and may inhabit active honey bee colonies during the fall and winter months. These rodents chew combs and frames to make room for building their nests. Mice urinate on combs and frames, making bees reluctant to use the combs or clean out these nests in the spring.


In some locations, skunks are a serious threat to successful beekeeping since they hamper the development of strong colonies. Being insectivorous (insect eating), skunks will raid bee yards nightly, scratch on hive entrances, and consume large numbers of bees. Although such attacks are most common in the spring, they also can occur throughout the summer and fall.


Bears are a serious threat to beekeeping operations, since they do a great deal of damage to hives and equipment. They normally visit apiaries at night, smashing the hives to eat brood and honey. Once bears locate an apiary, they return again and again, and it becomes exceedingly difficult to control their marauding behavior.

Brood Diseases

American foulbrood (Paenibacillus larvae = Bacillus larvae)

American foulbrood (AFB) is an infectious brood disease caused by a spore-forming bacterium. It is the most widespread and destructive of the brood diseases, afflicting queen, drone, and worker larvae alike. Adult bees, however, are not affected by AFB. This disease occurs in two forms: vegetative (rod-shaped bacterial cells) and spores. The spore stage is unique to this type of bacteria, as it may persist for 40 years or more.

European foulbrood (Melissococcus pluton)

European foulbrood (EFB) is a bacterial brood disease. It is considered a stress disease and is most prevalent in spring and early summer. It is less serious than AFB, and colonies can recover from infections. EFB does not form spores, but often overwinters on combs. It gains entry into the larva in contaminated brood food and multiplies rapidly within the gut of the larva.

Chalkbrood (Ascophaera apis)

Chalkbrood, a fungal brood disease of honey bees, is caused by a spore-forming fungus. Worker, drone, and queen larvae are susceptible. Spores of the fungus are ingested with the larval food. The spores germinate in the hind gut of the bee larva, but mycelial (vegetative) growth is arrested until the larva is sealed in its cell. When larvae are about 6 or 7 days old and sealed in their cells, the mycelia break through the gut wall and invade the larval tissues until the entire larva is over-come. This process generally takes from 2 to 3 days.


Sacbrood, a disease caused by a virus, usually does not result in severe losses. It is most common during the first half of the brood-rearing season. It often goes unnoticed, since it affects usually only a small percentage of the brood. Adult bees typically detect and remove infected larvae quickly. Often, if sacbrood is widespread enough for the beekeeper to observe the symptoms, the disease may be so severe that the adult worker population is reduced.

Bee parasitic mite syndrome (BPMS)

This situation most likely is associated with varroa mites, viruses, or a combination of both. Affected larvae die in the late larval or prepupal stage, stretched out in their cells often with their heads slightly raised. In the early stage of infection, they are white but dull rather than glistening, and they look deflated. This is one of a complex of symptoms that has been given the name “Bee Parasitic Mite Syndrome” or BPMS.

Adult Diseases


Paralysis is a symptom of adult honey bees and usually is associated with viruses. Two different viruses, chronic bee paralysis virus (CPV) and acute bee paralysis virus (APV), have been isolated from paralytic bees. Other suspected causes of paralysis include: pollen and nectar from plants such as buttercup, rhododendron, laurel, and some species of basswood; pollen deficiencies during brood rearing in the early spring; and consumption of fermented stored pollen.

Nosema (Nosema apis)

Nosema disease is caused by a spore-forming protozoan that invades the digestive tracts of honey bee workers, queens, and drones. Nosema spores are ingested with food or water by the adult bee. The spores germinate and multiply within the lining of the bee’s midgut. Millions of spores are shed into the digestive tract and are eliminated in the feces.

Deformed wings

Adult bees with deformed wings and bodies are common in honey bee colonies with varroa mite infestations. These deformities most likely are caused by varroa mites feeding on the bees as they develop, a virus (deformed wing virus), or perhaps a combination of both.

MAAREC/Penn State Extension Materials


Beekeeping Basics. 2004. Basic beginning beekeeping text. $7.50. Order from: Penn State College of Agricultural Sciences Publication Distribution Center, 112 Ag Administration Bldg., University Park, PA 16802. Phone: 814-865-6713.


  • Why Honey Bees? 1993. A 30-minute video for the public on the importance of honey bees. $35.00.
  • Varroa Mites: Life Cycle, Detection, and Control. 13-minute video. $25.00.

Order from: Penn State College of Agricultural Sciences Communications and Marketing, 229 Ag Administration Bldg. University Park, PA 16802. Phone: 814-863-2822.

Slide Sets

  • Honey Bee Diseases. 1998. Set of 53 slides and script. $60.00.
  • Honey Bee Parasites, Pests, and Predators. 1998. Slide set of 74 slides and script. $60.00

Order from: The Penn State Department of Entomology, 501 ASI Building, University Park, PA 16802. Phone: 814-865-1895.

Computer Program

  • Bee Aware: A Management Tool for the Diagnosis and Control of Honey Bee Diseases, Parasites, Pests, and Predators. A CD-ROM for Windows. $50.00.

Order from: The Penn State Department of Entomology, 501 ASI Building, University Park, PA 16802. Phone: 814-865-1895.



Honey Bee Disorders: Bacterial Diseases



American Foulbrood


Healthy larvae
Fig. 1
AFB-infected brood
Fig. 2
As the disease progresses, colonies may also display a pepper box symptom.
Fig. 3
Contents of ABF infected cells "rope out" up to one inch from the cell.
Fig. 4
Comb held so that sunlight is falling onto the longitudinal floors of the open cells; in many of the uncapped cells the scale can be seen as a black mass on the floor.
Fig. 5
A detailed view of black masses in comb caused by ABF.
Fig. 6


AFB is the most serious bacterial disease of honey bee brood and is caused by the bacterium Paenibacillus larvae. The disease is transferred and initiated only by the spore stage of the bacterium. The reason this disease is so serious is that the spores can remain viable and last indefinitely on beekeeping equipment. It is extremely contagious and spreads easily on contaminated equipment, hive tools, and beekeeper’s hands. A beekeeper’s best way to manage AFB is to avoid it.


Normal healthy larvae (Fig. 1) are glistening white, but AFB-infected brood turn chocolate-brown and melt into a gooey mass on the floor of the cell (Fig. 2). They may exhibit a syndrome called 'pupal tongue' where the tongue protrudes to the top of the cell, as shown in Fig. 2. As the disease progresses, colonies may also display a pepper box symptom (Fig. 3) where the cappings are perforated and sunken into the cell. When the larvae are brown and have not formed a hardened scale, the symptom of ropiness can be demonstrated. To do this, poke a stick into this mass, macerate it and withdraw it from the cell. If AFB is present the contents will 'rope out' (Fig. 4) up to one inch. This is the most definitive field test for AFB. As the dead larva dries, it becomes a black scale that adheres tightly to the cell floor. The comb in Figure 5 is being held so that sunlight is falling onto the longitudinal floors of the open cells; in many of the uncapped cells the scale can be seen as a black mass on the floor. See Figure 6 for a detailed view of black masses in comb. These scales are difficult to remove and remain a site for constant re-infection. A single scale can contain one billion spores, and it takes as few as 35 spores to trigger the disease. These scales are difficult to see and can easily be missed when purchasing used equipment. Colonies with high levels of AFB will have a foul odor similar to a chicken house. As more and more brood becomes infected and dies, the colony dwindles and eventually collapses.


One has an advantage if the beekeeper can purchase brand new hive equipment, install package bees, and maintain them perpetually in isolation from other apiaries. This, however, is not always practical or realistic. It always makes good sense to practice sanitation practices such as washing hands and hive tools between apiaries, avoiding used hive equipment of unknown or suspicious history, and avoiding feeding bees honey from unknown sources.


It is possible to breed for bees that are genetically resistant to AFB and other diseases. One of the most important characteristics in bees is the so-called 'hygienic behavior' – the ability of bees to detect and remove from the colony abnormal cells of brood. Hygienic queens are available from nationally-advertised queen breeders. See advertisements listed in American Bee Journal or Bee Culture.


Another tactic for preventing AFB and a similar disease, European foulbrood (EFB - see below), is biennial treatments of the veterinary antibiotic Terramycin™. However, this medication is no longer available over-the-counter; it is now by veterinary prescription only. It is fed as a mixture in either powdered sugar, sugar syrup, or in vegetable oil extender patties and limited to the months of September and February in Georgia. It is important to never feed Terramycin within four weeks of a nectar flow to avoid contaminating honey for human consumption.


The current restricted use of Terramycin is evidence of bacterial resistance that has developed in this country. In any case, it has always been preferable to rely on sanitation and resistant queen stock for the management of this disease.


AFB is regulated by the Georgia Department of Agriculture, and infected colonies are normally burned by state inspectors. Contact the Georgia Department of Agriculture state inspector at for more information or to report an infected colony. The spores of the AFB bacterium are extremely persistent in contaminated comb and hive parts. Although resistant bee colonies may clean up visible signs of infestation, it is more typical for AFB to be incurable and essentially doom the colony. Beekeepers should never maintain 'hospital yards' in which they group AFB colonies together in isolation. Such yards simply serve as reservoirs of disease that will serve to contaminate apiaries for miles around. It is equally inadvisable to treat infected colonies with Terramycin. The antibiotic will simply obscure visible signs of the disease, but the symptoms will rapidly recur once the antibiotic is removed.




European Foulbrood


Fig. 7

Fig. 8

Fig. 9

Fig. 10


EFB is a bacterial disease of honey bee brood. It is considered less virulent than American foulbrood, and colonies sometimes recover from infection. Its field symptoms are easily confused with those of AFB, but there are important differences. Instead of being a healthy pearly white (Fig. 7), larvae with EFB appear off-white, progressing to brown, and are twisted in various positions in the cell (Figs. 8, 9,10). Larvae with EFB usually die before they are capped whereas larvae with AFB die after they are capped.


The sanitation precautions recommended in the section on AFB apply also to EFB. Likewise, bee stocks selected for hygienic behavior can be expected to minimize outbreaks of EFB. The disease sometimes goes away on its own at the onset of a strong nectar flow. The beekeeper may be able to control the disease by simulating a nectar flow (by feeding sugar syrup) and by requeening the colony.


Preventive biennial treatments with Terramycin antibiotic, as recommended in the section on AFB, will also prevent EFB. As with AFB, it is important to consider antibiotic treatments as a preventive measure, not a cure. Terramycin treatments in EFB-infected colonies may actually be counterproductive because the medication permits those infected larvae to survive which would otherwise perish. These survivors then persist in the colony as a source of contamination. If the infected larvae are instead permitted to die, the house bees eject them from the hive and with them goes the source of infection. The bacterium does not form long-lived spores that persist on hive surfaces.




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