Honey Bee Pests & Diseases

This section provides information regarding the disease and pests that may afflict honey bee colonies in Ontario. Information provided includes the biology of the pest, how to monitor for them and the available registered treatments.

Please refer to the Ontario Recommendations for Honey Bee Disease Control for current guidance regarding disease management.

Note: No other treatments (chemical compounds) other than those listed are approved for use in bee hives in Ontario. Always follow label instructions for handling and applying any chemical in the bee hive. This is important not only for the beekeeper, but also for minimizing the possibility of creating resistance to the chemical. Dispose of waste chemicals as directed on the label instructions. Follow withdrawal period recommendations on treatment labels.

Ontario Honey Bee Diagnostic Labs



Like all other insects, honey bees (Apis mellifera) are susceptible to pests and diseases, the majority of which are specific to honey bees. These disorders can impact the health of a honey bee colony with effects ranging from minor stress to the death of the colony. It is important for beekeepers to be aware of these disorders, learn to identify them and effectively manage disorders to maintain healthy colonies.

American foulbrood (AFB) is the most serious brood disease of honey bees. AFB is caused by a spore-forming bacteria, Paenibacillus larvae; that is specific to honey bees. This disease is highly contagious, will weaken and in most cases kill a honey bee colony. AFB will also contaminate beekeeping equipment which must then be destroyed to prevent the spread of AFB to additional colonies. There is no cure for AFB. Beekeepers can only take steps to prevent an infection from establishing itself in a beekeeping operation.

Prevention of a widespread AFB outbreak in an operation is the best strategy. Finding an AFB infection as early as possible, and taking immediate action, is critical to prevent its spread within an operation.

Varroa mites, Varroa destructor, are the most serious threat to honey bees. Varroa were previously known by the species name Varroa jacobsoni. Varroa are relatively large external parasites that feed on the body fluids of adult and developing honey bees. Varroa cause physical damage, weaken bees and transmit a variety of pathogens, particularly viruses.

It is crucial that beekeepers manage the health of their honey bee colonies by suppressing the population of varroa in all of them throughout the beekeeping season. This usually requires chemical treatments. It is also essential for beekeepers to monitor the severity of varroa infestations to ensure the levels of infestation are kept below damaging thresholds. It is also important to be able to quantify the level of varroa infestation in a colony.

The small hive beetle (SHB), Aethina tumida Murray, is an emerging and invasive pest of the European honey bee. The SHB can impact colony health and damage beekeeping equipment.

There are many practices that beekeepers can employ to limit the exposure of their honey bee colonies to SHB. Beekeepers in all regions of Ontario should be aware of how to identify SHB and should familiarize themselves with the biology of SHB.