How to identify & report suspected pesticide poisoning incidents.
May 1, 2025
It is important for beekeepers in Ontario to understand the signs of poisoning and the process for reporting in the event of a possible exposure and/or subsequent bee kill.
Symptoms of acute pesticide poisoning of honey bees may be much easier to recognize than chronic symptoms. Pesticide damage may take place at an individual or colony level. The impact of pesticide poisoning to a colony may be short-lived or longer lasting. Longer lasting may result from multiple pesticide applications to the same or different fields or when contaminated pollen is brought back to the colony and contaminates food stores.
Symptoms of Acute Poisoning at the Colony Level: Excessive numbers of dying and dead bees in front of the hive, on the bottom board or on top bars. This can take place within 24 hours of exposure. Dead bees at the entrance may represent only 10 - 20% of the total number being killed as more bees might die in the field. A sudden pronounced decrease in colony population (thousands of bees) in a previously strong colony in the middle of the spring or summer season. The colony may stop growing in population during a time of the season where they should be normally increasing. Brood may become chilled within days or weeks due to insufficient workers to maintain and care for the brood. Dead larvae, being pulled out of the cells. Sudden aggressive behaviour in the colony, queen supesedure, repeated queen failures. | Symptoms of Acute Poisoning in Individual Honey Bees: Paralysis, trembling, stupefaction, disorientation and erratic behaviours by worker bees. Honey bees regurgitating, sometimes where many dead and dying bees form a wet, sticky mass. Loss of hairs: bees appear dark. The presence of only young (fuzzy looking) bees, indicating a major loss of older foragers. Sub-Lethal Effects at the Colony Level: Decrease in population, lack of colony development. Queen health issues, such as a spotty brood pattern. Dead larvae are dried out. |
We encourage all beekeepers to report even suspected chronic or acute bee poisonings as soon as possible.
The process for reporting suspected pesticide-related bee losses has recently been updated. In the past, suspected pesticide incidents were reported through the Ontario Ministry of Agriculture, Food, and Agribusiness (OMAFA) loss reports. This required some manual triaging and forwarding of information to the Ministry of Environment Conservation and Parks (MECP). The new process is as follows:
1. File a report with MECP
Beekeepers should report suspected pesticide incidents directly to the MECP through the Spills Action Centre by phoning 416-325-3000 or 1-800-268-6060, or by contacting their MECP district office
2. MECP officer response
The MECP Environmental Compliance Officer will contact the beekeeper and determine how to respond to the incident. This may involve a site visit to
collect information, which may include taking samples.
3. Legal samples may be taken
If a legal sample is collected by the MECP Environmental Compliance Officer, it will be transported and tested using a chain of custody to ensure that the
results are valid and can be used in any follow-up action that may be required.
4. Collecting your own sample
The responding officer may not be able to arrive on site immediately, and pesticides can break down rapidly in the environment. Beekeepers may
take a sample as soon as they suspect a pesticide incident (this sample will not be considered a legal sample, but it can be used as important information in any follow-up work for the incident). Samples can be collected in a clean glass or plastic jar and placed in the freezer. Most laboratories require about 350 bees for analysis and this sample can be provided to the responding officer during the site visit.
5. Results from the MECP
The results of the MECP testing will be returned to the beekeeper. If the testing results indicate the presence of a pesticide, then the results can be forwarded to Health Canada’s Pest Management Regulatory Agency (PMRA) to be included in their database. This database is used when pesticides are reviewed for re-registration every five years.
6. MECP follow-up actions
Follow-up actions by MECP may occur, depending on the results of the testing and the on-site investigations. In some cases, this can lead to charges for violations under the Pesticide Act if sufficient evidence is found.
7. Speak to a lawyer
Beekeepers may also choose to obtain legal advice to review the information and pursue a civil suit for recovery of damages. Beekeepers are encouraged to report suspected pesticide incidents to ensure that good baseline information is gathered and to help rapidly detect any concerning changes or trends in incident reporting that may warrant wider investigation.
Please let the OBA know if you have reported a bee kill. info@ontariobee.com
More Information:
National Pesticides Call Line Service: 1-800-267-6315
File(s):
